Endocrine System N141
Bridge to NCLEX Examination The number of the question corresponds to the same-numbered outcome at the beginning of the chapter. 1.A characteristic common to all hormones is that they a.circulate in the blood bound to plasma proteins. b.influence cellular activity of specific target tissues. c.accelerate the metabolic processes of all body cells. d.enter a cell to alter the cell's metabolism or gene expression.
1. Correct answer: b Rationale: A hormone is a chemical substance synthesized and secreted by a specific organ or tissue. Most hormones have common characteristics, including: (1) secretion in small amounts at variable but predictable rates, (2) circulation through the blood (3) binding to specific cell receptors in the cell membrane or within the cell.
Aldosterone. Aldosterone is a potent mineralocorticoid that maintains extracellular fluid volume. - It acts on the renal tubule to promote renal reabsorption of sodium and excretion of potassium and hydrogen ions. -Aldosterone synthesis and secretion are stimulated by angiotensin II, hyponatremia, and hyperkalemia. -ANP and hypokalemia inhibit aldosterone synthesis and release.
Adrenal Androgens. The adrenal cortex secretes small amounts of androgens that are converted to sex steroids in peripheral tissues: testosterone in men and estrogen in women. The most common adrenal androgens are dehydroepiandrosterone (DHEA) and androstenedione. In postmenopausal women the major source of estrogen is from the peripheral conversion of adrenal androgen to estrogen. Because they are precursors to other sex steroids, their actions are similar to those of testosterone and estrogen.
Calcitonin. Calcitonin is produced by C cells (parafollicular cells) of the thyroid gland in response to high circulating calcium levels. Calcitonin inhibits the transfer of calcium from bone to blood, increases calcium storage in bone, and increases renal excretion of calcium and phosphorus, thereby lowering serum calcium levels. Calcitonin and PTH regulate calcium balance.
Parathyroid Glands Two pairs of parathyroid glands are usually arranged behind each thyroid lobe (see Fig. 48-8). Although there are usually four glands, their number may range from two to six
Gastrointestinal: -Constipation -Passage of infrequent hard stools -*Hypothyroidism or calcium imbalances caused by hyperparathyroidism
Reproductive: -Changes in reproductive function -Menstrual irregularities, decreased libido, decreased fertility, impotence -Reproductive function is significantly affected by various endocrine abnormalities, including pituitary hypofunction, growth hormone excess, thyroid dysfunction, and adrenocortical dysfunction
TABLE 48-3 GERONTOLOGIC ASSESSMENT DIFFERENCES: Endocrine System Thyroid Atrophy of thyroid gland. TSH, T3, and T4 secretion are decreased. Increased nodules. Increased incidence of hypothyroidism with aging. However, most older adults maintain adequate thyroid function. Thyroid hormone replacement dose lower in older adults.
TABLE 48-3 GERONTOLOGIC ASSESSMENT DIFFERENCES: Endocrine System Parathyroid Increased secretion of PTH and increased basal level of PTH. Increased calcium resorption from bone. Hypercalcemia, hypercalciuria (may reflect defective renal mechanism).
1. level of homrmones: -note sample time on the lab slip -note fasting status 2. Ultrasound -thyroid nodules, adrenal gland masses 3. MRI -P.t must lie still for 25-30 min 4. CT -if contrast is used check for iodine allergy
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2. A patient is receiving radiation therapy for cancer of the kidney. The nurse monitors the patient for signs and symptoms of damage to the a. pancreas. b.thyroid gland. c.adrenal glands. d.posterior pituitary gland.
2. Correct answer: c Rationale: The adrenal glands are small, paired, highly vascularized glands located on the upper portion of each kidney.
3. A patient has a serum sodium level of 152 mEq/L (152 mmol/L). The normal hormonal response to this situation is: a.release of ADH. b.release of ACTH. c.secretion of aldosterone. d.secretion of corticotropin-releasing hormone.
3. Correct answer: a Rationale: The most important stimulus of antidiuretic hormone (ADH) secretion is plasma osmolality, which is a measure of solute concentration in circulating blood. -Plasma osmolality increases when there is a decrease in extracellular fluid or an increase in solute concentration. -The increased plasma osmolality activates osmoreceptors, which are extremely sensitive, specialized neurons in the hypothalamus. -These activated osmoreceptors stimulate ADH release. When ADH is released, the renal tubules reabsorb water, which causes urine to be more concentrated.
4. All cells in the body are believed to have intracellular receptors for: a.insulin. c.growth hormone. b. glucagon. d.thyroid hormone.
4. Correct answer: d Rationale: There are two types of receptors: those that are within the cell (e.g., steroid and thyroid hormone receptors) and those that are on the cell membrane (e.g., water-soluble hormone receptors). -Thyroid hormone receptors are located inside the cell. -Because these hormones are lipid soluble, they pass through the target cell membrane by passive diffusion and bind to receptor sites located in the cytoplasm or nucleus of the target cell.
1. What are the possible causes of L.M.'s weight gain, fatigue, and irritability? Answer: Thyroid dysfunction, Cushing syndrome ----------------------------------------------------------------------------------- 2. What would be your priority assessment of L.M.? Answer: Because of L.M.'s vague complaints, assessment of her psychosocial and neuromuscular status would be a priority, as well as nutritional status related to weight gain.
4. What should be included in the physical assessment? What would you be looking for? Vital signs—looking for hypertension, tachycardia Height and weight to assess actual weight gain and determine BMI. Observe skin color and integrity—looking for hyperpigmentation, striae, poorly healing skin ulcerations Observe for abnormal hair distribution, specifically hirsutism Observe fat distribution—looking for buffalo hump, thin extremities with truncal obesity, moon face Inspect for edema Assess patient's mental and emotional status throughout exam, noting any changes in affect ------------------------------------------------------------------------------------------------- *What diagnostic studies might you expect to be ordered? CBC, basic metabolic panel (electrolytes, BUN, creatinine) Fasting blood glucose (FBG) TSH, free T4 Plasma cortisol levels (drawn in morning) Plasma ACTH levels (drawn in the morning)
5. When obtaining subjective data from a patient during assessment of the endocrine system, the nurse asks specifically about: a.energy level. b.intake of vitamin C. c.employment history. d.frequency of sexual intercourse.
5. Correct answer: a Rationale: The nurse should ask about energy levels, particularly in comparison with the patient's past energy level. -Fatigue and hyperactivity are two common problems associated with endocrine problems.
6. Endocrine disorders often go unrecognized in the older adult because: a.symptoms are often attributed to aging. b.older adults rarely have identifiable symptoms. c.endocrine disorders are relatively rare in the older adult. d.older adults usually have subclinical endocrine disorders that minimize symptoms.
6. Correct answer: a Rationale: Assessment of the effects of aging on the endocrine system is difficult because the subtle changes of aging often mimic manifestations of endocrine disorders.
7. An abnormal finding by the nurse during an endocrine assessment would be (select all that apply) a.blood pressure of 100/70 mm Hg. b.excessive facial hair on a woman. c.soft, formed stool every other day. d.3-lb weight gain over last 6 months. e.hyperpigmented coloration in lower legs.
7. Correct answers: b, e Rationale: Hirsutism (i.e., excessive facial hair on women) may indicate Cushing syndrome or prolactinoma, a pituitary tumor. -Hyperpigmentation (i.e., darkening of the skin, particularly increases and skin folds) may indicate Addison's disease, which is caused by increased secretion of melanocytestimulating hormone, or it may indicate acanthosis nigricans.
8. A patient has a total serum calcium level of 3 mg/dL (1.5 mEq/L). If this finding reflects hypoparathyroidism, the nurse would expect further diagnostic testing to reveal a.decreased serum PTH. b.increased serum ACTH. c.increased serum glucose. d.decreased serum cortisol levels.
8. Correct answer: a Rationale: Normal serum calcium levels are 8.6 to 10.2 mg/dL. The serum calcium level is low in hypoparathyroidism, and the serum parathyroid hormone (PTH) level is decreased.
The patient with type 1 diabetes mellitus on a tight glucose control regimen who complains of sweating or nightmares may be experiencing hypoglycemia. Ask the patient about snoring, which could indicate sleep apnea; this is especially common in men with diabetes mellitus.
A patient with an endocrine dysfunction may manifest apathy or depression. Question both the patient and family to determine if any cognitive changes are present. Memory deficits and an inability to concentrate are common in endocrine disorders. Visual changes such as blurring or double vision could indicate endocrine problems. Headaches may indicate abnormal pituitary growth.
Adrenal Medulla- Catecholamines: 1.Epinephrine (adrenaline) -Sympathetic effectors -Increases in response to stress. Enhances and prolongs effects of sympathetic nervous system. 2.Norepinephrine (noradrenaline) -Sympathetic effectors -Increases in response to stress. Enhances and prolongs effects of sympathetic nervous system. 3. Dopamine
Adrenal Cortex- 1.Glucocorticoids: Corticosteroids( ac, and sh blood glucose determination) (e.g., cortisol, hydrocortisone) -All body tissues -blood glucose concentration -Promote metabolism. Increased in response to stress. Antiinflammatory. -Vascular integrity and fluid volume 2. Androgens (e.g., DHEA, androsterone) and estradiol -Reproductive organs -Promote growth spurt in adolescence, secondary sex characteristics, and libido in both sexes. 3. Mineralocorticoids (e.g., aldosterone-maintain ECF) -Kidney -Regulate sodium and potassium balance and thus water balance.
Parathyroid Hormone: The parathyroid glands secrete parathyroid hormone (PTH), also called parathormone. Its major role is to regulate the blood level of calcium. -PTH acts on bone, the kidneys, and indirectly on the GI tract. - PTH stimulates the transfer of calcium from the bone into the blood and inhibits bone formation, resulting in increased serum calcium and phosphate. -In the kidney, PTH increases calcium reabsorption and phosphate excretion. -In addition, PTH stimulates the renal conversion of vitamin D to its most active form (1,25-dihydroxyvitamin D3). -This active vitamin D promotes absorption of calcium and phosphorus by the GI tract, which ultimately increases bone mineralization. -The secretion of PTH is directly regulated by a feedback system. -When the serum calcium level is low, PTH secretion increases. When the serum calcium level rises, PTH secretion falls. -In addition, high levels of active vitamin D inhibit PTH, and low levels of magnesium stimulate PTH secretion.
Adrenal Medulla: The adrenal medulla is the inner part of the gland and consists of sympathetic postganglionic neurons. -The medulla secretes the catecholamines epinephrine (adrenaline), norepinephrine (noradrenaline), and dopamine. -Catecholamines are synthesized from the amino acid phenylalanine. Catecholamines, usually considered neurotransmitters, are hormones when secreted by the adrenal medulla because they are released into the circulation. They are an essential part of the body's "fight or flight" response to stress (see Chapter 7).
Somatomedin C (insulin-like growth factor 1 [IGF-1]) Evaluates GH secretion. Provides a more accurate reflection of mean plasma concentration of GH because it is not subject to circadian rhythm and fluctuations. Low levels indicate GH deficiency. High levels indicate GH excess. Reference interval: 135-449 ng/mL Overnight fasting is preferred but not necessary.
Growth hormone (GH) stimulation Insulin tolerance test: Regular insulin given IV and blood drawn at −30, 0, 30, 45, 60, and 90 min for measurement of glucose and GH. Reference interval: GH >5 mcg/L Arginine-GHRH test: GHRH bolus followed by 30-min infusion of arginine. Reference interval: GH >4.1 mcg/L Patient must be NPO after midnight. -Water is permitted on morning of test. IV access is established for administration of medications and frequent blood sampling. -Continually assess for hypoglycemia and hypotension. -Keep 50% dextrose and 5% dextrose IV solution at the bedside in case severe hypoglycemia occurs.
Adrenal Cortex: The adrenal cortex is the outer part of the adrenal gland. It secretes several steroid hormones, including: glucocorticoids mineralocorticoids and androgens. -Cholesterol is the precursor for steroid hormone synthesis. Glucocorticoids (e.g., cortisol) are named for their effects on glucose metabolism. Mineralocorticoids (e.g., aldosterone) are essential for the maintenance of fluid and electrolyte balance. The term corticosteroid refers to hormones synthesized by the adrenal cortex excluding androgens.
Cortisol. (if your going to draw cortisol do them in the morning) Cortisol, the most abundant and potent glucocorticoid, is necessary to maintain life and protect the body from stress. -Cortisol is secreted in a diurnal pattern (see Fig. 48-5). -The major control of cortisol is through a negative feedback mechanism that involves the secretion of corticotropin-releasing hormone (CRH) from the hypothalamus. CRH stimulates the secretion of ACTH by the anterior pituitary. One major function of cortisol is the regulation of blood glucose concentration through stimulation of hepatic glucose formation (gluconeogenesis). -Cortisol decreases peripheral glucose use in the fasting state, inhibits protein synthesis, and stimulates the mobilization of glycerol and free fatty acids. -Cortisol also helps maintain vascular integrity and fluid volume through its action on mineralocorticoid receptors. -Cortisol levels are increased by stress, burns, infection, fever, acute anxiety, and hypoglycemia. Glucocorticoids inhibit the inflammatory response and are considered antiinflammatory. Cortisol decreases the inflammatory response by stabilizing the membranes of cellular lysosomes and preventing increased capillary permeability. The lysosomal stabilization reduces the release of proteolytic enzymes and thereby their destructive effects on surrounding tissue. Cortisol can also inhibit production of prostaglandins, thromboxanes, and leukotrienes (see Chapter 12, Fig. 12-2) and alter the cell-mediated immune response.
Often the patient with an endocrine disorder is unable to sustain life's roles.
Document the development of abnormal secondary sex characteristics such as facial hair (hirsutism) in women. -Ask a detailed history of menstruation and pregnancy. - Menstrual dysfunction may be seen in disorders of the ovaries and pituitary, thyroid, and adrenal glands. - A history of large-birth-weight babies may indicate gestational diabetes, which may put the patient at a higher risk of developing diabetes mellitus. - The inability to lactate may indicate a pituitary disorder Male sexual dysfunction may take the form of impotence, decreased libido, infertility, or the lack of development of secondary sexual characteristics. -Retrograde ejaculation can occur in diabetes mellitus.
Inspect the size and contour of the head. Facial features should be symmetric. - Hyperreflexia and facial muscle contraction upon percussion of the facial nerve (Chovostek's sign) may occur in hypoparathyroidism. -Inspect the eyes for position, symmetry, and shape. Large and protruding eyes (exophthalmos) are associated with hyperthyroidism. -Assess visual acuity using a Snellen eye chart. Visual field loss may indicate a pituitary tumor. In the mouth, inspect the buccal mucosa, condition of teeth, and tongue size. Note hair distribution on the scalp and face. -Hearing loss is common in acromegaly (from excess GH).7
Endocrine System Use this checklist to ensure the key assessment steps have been done. Subjective: 1.Ask the patient about any of the following and note responses: Excessive or increased thirst Excessive or decreased urination Excessive hunger Intolerance to heat or cold Excessive sweating Recent weight gain or loss Objective: Diagnostic- Check the following laboratory results for critical values. Potassium Glucose Sodium Glycosylated hemoglobin (Hb A1C) Thyroid studies: TSH, T3, T4 Inspect/Measure: 1.Body temperature 2.Height and weight 3.Alertness and emotional state 4.Skin for changes in color and texture 5.Hair for changes in color, texture, and distribution Auscultate: heart rate, blood pressure Palpate: Extremities for edema Skin for texture and temperature Neck for thyroid size, shape T3, Triiodothyronine; T4, thyroxine; TSH, thyroid-stimulating hormone.
Regulation of hormone secretion: What stimulate or inhibits hormone synthesis and secretion? Answer: Feedback= is based on teh blood level of the hormone or a substance regulated by or responsive to that hormone Negative feedback= is the most common type e.g. insulin when blood sugar is high insulin is released when it is low insulin is not released. Positive feedback= increases the target organ action beyond normal- an example would be oxytocin which is released as the fetus enters to birth canal to produce stronger uterine contractions Complex = involves communication between via hormones among several gland to turn on or off target organ secretion. Rhythms- e.g. circadian rhythm in which a hormone level fluctuates predictably during a 24 hour period- the book gives ex. of TSH, Growth hormone and Cortisol- one has to keep in mind where the body is when lab tests are collected.... depending on the time of day the level of homrone can be normal but really it is abnormally low or high given what one would expect based on the circadian rhythm- look under cortisol for examples of the diagnostic studies on page 1215 table 48-8
FBS (fasting blood sugar): 70 - 99 HgbA1C: 4.0 - 6.0%
Gonadotropins- • Follicle-stimulating hormone (FSH) • Luteinizing hormone (LH) Useful in distinguishing primary gonadal problems from pituitary insufficiency. - In women, there are marked differences during menstrual cycle and in postmenopausal period. - Levels are low in pituitary insufficiency and high in primary gonadal failure. There is no special preparation of the patient. - Only one blood tube is needed for both FSH and LH. -Note on the laboratory slip time of menstrual cycle or whether woman is menopausal.
FSH: Women: -Follicular phase: 1.37 - 9 .9 mU/mL -Ovulatory phase: 6.17 - 1 7.2 mU/mL -Luteal phase: 1.09 - 9.2 mU/mL -Postmenopause: 19.3 - 100.6 mU/mL -Men: 1.42 -1 5.4 mU/mL LH- -Women: Follicular phase: 1.68-15 IU/L -Ovulatory phase: 21.9-56.6 IU/L -Postmenopause: 14.2-52.3 IU/L Men: 1.24-7.8 IU/L
*data regarding past radiation therapy to the head and neck are especially important when thyroid or pituitary dysfunction is suspected.
Genetic Risk Alert Pituitary- • Nephrogenic diabetes insipidus can be inherited as a sex-linked or autosomal disorder. Thyroid- • Genetics has a role in many cases of hypothyroid and hyperthyroid disorders. •Hashimoto's thyroiditis= the most common cause of hypothyroidism, is a chronic autoimmune disorder that has a genetic basis. •Graves' disease= a cause of hyperthyroidism, is an autoimmune disease in which genetic factors are involved. •Graves' disease, a cause of hyperthyroidism, is an autoimmune disease in which genetic factors are involved. Multiple Endocrine Neoplasia: • Multiple endocrine neoplasia is when two or more different endocrine tumors occur in a person and there is evidence for either a causative mutation or genetic transmission. • The features of this disorder are relatively consistent within any one family. • A common endocrine tumor is medullary thyroid carcinoma. • Some people with this disorder also develop pheochromocytoma. Diabetes Mellitus: • Genetics has a strong role in the development of type 2 diabetes, and to a lesser extent in type 1 diabetes. -Heredity often plays an important role in the development of endocrine dysfunction. -Ask about the occurrence of diabetes mellitus, thyroid disease, and endocrine gland cancers, since these conditions have a familial tendency. - A genetic assessment of family members may be appropriate
Insulin. Insulin is the principal regulator of metabolism and storage of ingested carbohydrates, fats, and proteins. Insulin facilitates glucose transport across cell membranes in most tissues. However, the brain, nerves, lens of the eye, hepatocytes, erythrocytes, and cells in the intestinal mucosa and kidney tubules are not dependent on insulin for glucose uptake. An increased blood glucose level is the major stimulus for insulin synthesis and secretion. Other stimuli to insulin secretion are increased amino acid levels and vagal stimulation. Insulin secretion is usually inhibited by low blood glucose levels, glucagon, somatostatin, hypokalemia, and catecholamines. A major effect of insulin on glucose metabolism occurs in the liver, where the hormone enhances glucose incorporation into glycogen and triglycerides by altering enzymatic activity and inhibiting gluconeogenesis. After a meal, insulin is responsible for the storage of nutrients (anabolism). Another major effect occurs in peripheral tissues, where insulin facilitates glucose transport into cells, transport of amino acids across muscle membranes and their synthesis into protein, and transport of triglycerides into adipose tissue.
Gerontologic Considerations Effects of Aging on Endocrine System Normal aging has many effects on the endocrine system (Table 48-3). These include (1) decreased hormone production and secretion, (2) altered hormone metabolism and biologic activity, (3) decreased responsiveness of target tissues to hormones, and (4) alterations in circadian rhythms. Assessment of the effects of aging on the endocrine system may be difficult because the subtle changes of aging may mimic manifestations of endocrine disorders. Endocrine problems may manifest differently in an older adult than in a younger person. Older adults may have multiple co-morbidities and take medications that alter the body's usual response to endocrine dysfunction. Symptoms of endocrine dysfunction such as fatigue, constipation, or mental impairment are often missed because they are attributed solely to aging. For example, the symptoms of thyroid disease may be attributed to aging, resulting in delayed treatment. It is important to assess renal function (serum creatinine, blood urea nitrogen [BUN]) in the older adult undergoing diagnostic studies with contrast medium. Older adults with renal dysfunction may be more prone to renal failure with the use of contrast medium.4
Pancreas The pancreas is a long, tapered, lobular, soft gland located behind the stomach and anterior to the first and second lumbar vertebrae. The pancreas has both exocrine and endocrine functions. The hormone-secreting portion of the pancreas is referred to as the islets of Langerhans. The islets account for less than 2% of the gland and consist of four types of hormone-secreting cells: α, β, delta, and F cells. α Cells produce and secrete the hormone glucagon. Insulin and amylin are produced and secreted by β cells. Somatostatin is produced and secreted by the delta cells. Pancreatic polypeptide (PP) is secreted by the F (or PP) cells.
Glucagon. Glucagon is synthesized and released from pancreatic α cells and the gut in response to low levels of blood glucose, protein ingestion, and exercise. Glucagon increases blood glucose by stimulating glycogenolysis, gluconeogenesis, and ketogenesis. Glucagon and insulin function in a reciprocal manner to maintain normal blood glucose levels. In the fasting state, hormones such as catecholamines, cortisol, and glucagon break down stored complex fuels (catabolism) to provide glucose as fuel for energy.
Pancreas (Islets of Langerhans) Insulin (from β cells) -General -Promotes movement of glucose out of blood and into cells. Amylin (from β cells) -Liver, stomach -Decreases gastric motility, glucagon secretion, and endogenous glucose release from liver. Increases satiety. Glucagon (from α-cells) -General -Stimulates glycogenolysis and gluconeogenesis. Somatostatin -Pancreas -Inhibits insulin and glucagon secretion. Pancreatic polypeptide -General -Influences regulation of pancreatic exocrine function and metabolism of absorbed nutrients.
Gonads Women: Ovaries Estrogen -Reproductive system, breasts -Stimulates development of secondary sex characteristics, preparation of uterus for fertilization and fetal development. Stimulates bone growth. Progesterone -Reproductive system -Maintains lining of uterus necessary for successful pregnancy. Men: Testes -Testosterone -Reproductive system -Stimulates development of secondary sex characteristics, spermatogenesis.
Integumentary: Hyperpigmentation- Darkening of the skin, particularly in creases and skinfolds *Addison's disease caused by increased secretion of melanocyte-stimulating hormone; acanthosis nigricans Depigmentation (vitiligo)- Patchy areas of light skin *May be a marker of autoimmune endocrine disorders Striae- Purplish red marks below the skin surface. Usually seen on abdomen, breasts, and buttocks *Cushing syndrome Changes in skin texture- Thick, cold, dry skin *Hypothyroidism Thick, leathery, oily skin- Growth hormone excess (acromegaly) Warm, smooth, moist skin- *Hyperthyroidism Changes in hair distribution- Hair loss *Hypothyroidism, hyperthyroidism, decreased pituitary secretion Diminished axillary and pubic hair- Cortisol deficiency Hirsutism (excessive facial hair on women)- *Cushing syndrome, prolactinoma (a pituitary tumor) Skin ulceration- Areas of ulcerated skin, most commonly found on legs and feet Peripheral neuropathy and peripheral vascular disease, which are contributory factors in the development of diabetic foot ulcers Edema- -Generalized edema -Mucopolysaccharide accumulation in tissue in* hypothyroidism
Head and Neck- Visual changes- Decreased visual acuity and/or decreased peripheral vision *Pituitary gland enlargement or tumor leading to pressure on optic nerve Exophthalmos- Eyeball protrusion from orbits Occurs in *hyperthyroidism as a result of fluid accumulation in eye and retroorbital tissue Moon face- Periorbital edema and facial fullness *Cushing syndrome as a result of increased cortisol secretion Myxedema- Puffiness, periorbital edema, masklike affect Hydrophilic mucopolysaccharides infiltrating dermis in patients with *hypothyroidism Goiter- Generalized enlargement of thyroid gland *Hyperthyroidism,* hypothyroidism, *iodine deficiency Thyroid nodule(s)- Localized enlargement of thyroid gland May be benign or malignant
Reported changes in appetite and weight can indicate endocrine dysfunction. Weight loss with increased appetite may indicate hyperthyroidism or diabetes mellitus. Weight gain may indicate hypothyroidism or hypocortisolism. Truncal obesity, purple abdominal striae, and thin extremities occur in patients with hypercortisolism. Obese individuals are more likely to develop type 2 diabetes. Ask if there have been problems with nausea, vomiting, or diarrhea. -Difficulty swallowing or a change in neck size may indicate an enlarged thyroid gland. - Increased SNS activity, including nervousness, palpitations, sweating, and tremors, may indicate thyroid dysfunction or a rare tumor of the adrenal medulla (pheochromocytoma). -Heat or cold intolerance may indicate hyperthyroidism or hypothyroidism, respectively. Also ask about changes in the patient's skin, particularly on the face, neck, hands, or body creases. Ask if the patient has noticed any change in the distribution of hair anywhere on the body. Changes in the texture of the skin and whether it seems thicker or drier may indicate endocrine dysfunction. Hair loss can indicate hypopituitarism, hypothyroidism, hyperthyroidism, hypoparathyroidism, or increased testosterone and other androgens. -Increased body hair may indicate hypercortisolism. -Decreased skin pigmentation can occur in hypopituitarism, hypothyroidism, and hypoparathyroidism whereas increased skin pigmentation, particularly in sun-exposed areas, can indicate hypocortisolism. -A patient with hypothyroidism or excess GH may have skin that feels coarse or leathery. - A patient with hyperthyroidism may mention fine, silky hair.
Increased thirst and urination can indicate Diabetes Mellitus (pancreas disorder) or diabetes Insipidus (Pituitary Disorder). -Ask about the frequency and consistency of bowel movements. -Frequent defecation may indicate Hyperthyroidism or autonomic neuropathy of Diabetes Mellitus. -Constipation is also seen in patients with hypothyroidism, hypoparathyroidism, and hypopituitarism.
some endocrine conditions are exacerbated by stress, ask patients about their level of stress and usual coping patterns. - Patients' perception of the impact of their condition and treatments on their lifestyle is very important.
Integument. Note the color and texture of the skin, hair, and nails. -Note the overall skin color as well as pigmentation and possible ecchymosis (bruise). -Hyperpigmentation, or "bronzing" of the skin (particularly on knuckles, elbows, knees, genitalia, and palmar creases), is a classic finding in Addison's disease. -Palpate the skin for texture and moisture. Examine hair distribution not only on the head but also on the face, trunk, and extremities. -Also assess the appearance and texture of the hair. Dull, brittle hair; excessive hair growth; or hair loss may indicate endocrine dysfunction. -Assess any wounds and ask how long they have been present.
Hormone Receptors: -Hormones exert their effects by recognizing their target tissues and attaching to receptor sites in a "lock-and-key" type of mechanism
Lipid-Soluble and Water-Soluble Hormones: -Hormones are classified by their chemical structure as either lipid soluble or water soluble. -The differences in solubility become important in understanding how the hormone interacts with the target cell. -Lipid-soluble hormones are synthesized from cholesterol and are produced by the adrenal cortex, sex glands, and thyroid. - Lipid-soluble hormones (steroids, thyroid) are relatively small molecules that cross the target cell membrane by simple diffusion. -Steroid and thyroid hormone receptors are located inside the cell. -Lipid-soluble hormones are bound to plasma proteins for transport in the blood. Although lipid-soluble hormones are inactive when bound to plasma proteins, they can be released when appropriate and immediately exert their action at the target tissue. Water-soluble hormones (insulin, growth hormone [GH], and prolactin) have receptors on or in the cell membrane. -Water-soluble hormones circulate freely in the blood to their target tissues, where they act. -Water-soluble hormones are not dependent on plasma proteins for transport (see Fig. 48-3).
Consequently, patients with endocrine dysfunction may be labeled as depressed, malingering, apathetic, or neurotic. - In other instances, or in late stages of endocrine dysfunction, the patient may be seen with symptoms that are life threatening and demand immediate intervention.
Medications: Ask about the use of all medications (both prescription and over-the-counter drugs), herbs, and dietary supplements. - Ask about the reason for taking the drug, the dosage, and the length of time the drug has been taken. - In particular, ask about the use of hormone replacements. -Knowing that the patient is currently taking hormone replacements such as insulin, thyroid hormone, or corticosteroids (e.g., prednisone) alerts you to possible problems associated with the use of these agents (e.g., corticosteroids may cause increased blood glucose levels and bone loss with long-term use). - The side and adverse effects of many nonhormone medications can contribute to problems affecting endocrine function (e.g., many drugs can affect blood glucose levels) (see eTable 49-1).
Inspect the contour of the abdomen and note the symmetry and color. *Cushing Syndrome= (hypercortisolism) causes the skin to be fragile, resulting in purple-blue striae across the abdomen. -Note general obesity or truncal obesity. *Auscultate bowel sounds.
Muscular spasms of the hand elicited on application of an occlusive blood pressure cuff for 3 minutes (Trousseau's sign) may be noted in hypoparathyroidism.
Cardiovascular: Chest pain: -Angina caused by increased metabolic demands, effusions -*Hyperthyroidism,* hypothyroidism Dysrhythmias: -Tachycardia, atrial fibrillation -*Hypothyroidism or *hyperthyroidism, hypoparathyroidism or hyperparathyroidism, pheochromocytoma Hypertension -Elevated blood pressure caused by increased metabolic demands and catecholamines -*Hyperthyroidism, pheochromocytoma, *Cushing syndrome
Musculoskeletal Changes in muscular strength or muscle mass -Generalized weakness and/or fatigue -Common symptoms associated with many endocrine problems, including pituitary, thyroid, parathyroid, and adrenal dysfunctions -*Diabetes mellitus,* Diabetes insipidus Decreased muscle mass -Specifically seen in those with growth hormone deficiency and in* Cushing syndrome secondary to protein wasting Enlargement of bones and cartilage: -Coarsening of facial features. - Increases in size of hands and feet over a period of several years Gradual enlargement and thickening of bony tissue occurring with growth hormone excess in adults as seen in *acromegaly
Nutrition: page 1147 Changes in weight: -Weight loss -*Hyperthyroidism caused by increases in metabolism, type 1 *diabetes mellitus, *diabetic ketoacidosis Altered glucose levels: -Weight gain -*Hypothyroidism, *Cushing syndrome,* type 2 diabetes mellitus Increased serum glucose: -Diabetes mellitus, Cushing syndrome, growth hormone excess
Neurologic- Lethargy: -State of mental sluggishness or somnolence Hypothyroidism Tetany: -Intermittent involuntary muscle spasms usually involving the extremities *Severe hypocalcemia that can occur with hypoparathyroidism Seizure: -Sudden involuntary contraction of muscles -Consequence of a pituitary tumor -Fluid and electrolyte imbalance associated with excessive ADH secretion -Complications of diabetes mellitus, severe hypothyroidism Increased deep tendon reflexes -Hyperreflexia -Hyperthyroidism, hypoparathyroidism
Thyroid Thyroxine (T4): -All body tissues Precursor to T3. Triiodothyronine (T3): -All body tissues -Regulates metabolic rate of all cells and processes of cell growth and tissue differentiation. Calcitonin: -Bone tissue -Regulates calcium and phosphorus blood levels. Decreases serum Ca2+ levels.
Parathyroids: Parathyroid hormone (PTH), or parathormone -Bone, intestine, kidneys -Regulates calcium and phosphorus blood levels. -Promotes bone demineralization and increases intestinal absorption of Ca2+. Increases serum Ca2+ levels.
Posterior Pituitary. The posterior pituitary is composed of nerve tissue and is essentially an extension of the hypothalamus. Communication between the hypothalamus and posterior pituitary occurs through nerve tracts known as the median eminence. The hormones secreted by the posterior pituitary, antidiuretic hormone (ADH) and oxytocin, are actually produced in the hypothalamus. These hormones travel down the nerve tracts from the hypothalamus to the posterior pituitary and are stored until their release is triggered by the appropriate stimuli (see Fig. 48-6). The major physiologic role of ADH (also called arginine vasopressin) is regulation of fluid volume by stimulating reabsorption of water in the renal tubules. ADH is also a potent vasoconstrictor. ADH secretion is stimulated by plasma osmolality (a measure of solute concentration of circulating blood) and hypovolemia (Fig. 48-7). Plasma osmolality increases when there is a decrease in ECF or an increase in solute concentration. The increased plasma osmolality activates osmoreceptors, which are extremely sensitive, specialized neurons in the hypothalamus. These activated osmoreceptors stimulate ADH release. Volume receptors in large veins, heart atria, and carotid arteries that sense pressure changes also contribute to ADH control. When ADH is released, the renal tubules reabsorb water and the urine becomes more concentrated. When ADH release is inhibited, renal tubules do not reabsorb water, resulting in a more dilute urine excretion. Oxytocin stimulates ejection of milk into mammary ducts during lactation and contraction of the uterus; it may also affect sperm motility. Oxytocin secretion is increased by stimulation of touch receptors in the nipples of lactating women and vaginal pressure receptors during childbirth.
Pineal Gland The pineal gland is located in the brain and is composed of photoreceptive cells. The secretion of the hormone melatonin is its primary function. Melatonin secretion is increased in response to exposure to the dark and decreased in response to light. The gland helps to regulate circadian rhythms and the reproductive system at the onset of puberty.
Other- Polyuria -Excessive urine output -Diabetes mellitus (secondary to hyperglycemia) or diabetes insipidus (associated with decreased ADH) Polydipsia -Excessive thirst -Extreme water losses in diabetes mellitus (with severe hyperglycemia) and diabetes insipidus, dehydration Decreased urine output -ADH leading to reabsorption of water from kidney tubules -Syndrome of inappropriate antidiuretic hormone (SIADH) Thermoregulation -Cold insensitivity -Hypothyroidism caused by a slowing of metabolic processes -Heat intolerance -Hyperthyroidism caused by excessive metabolism *ADH, Antidiuretic hormone.
Pituitary Studies- Blood Studies -Growth hormone (GH) (somatotropin) -Evaluates GH secretion. -Used to identify GH deficiency or GH excess. GH levels are affected by time of day, food intake, and stress. -Difficult to interpret significance of isolated GH level. Further evaluation requires stimulation tests (see below). Men: <4 ng/mL (<4.0 mcg/L) Women: <18 ng/mL (<18 mcg/L) Values >50 ng/mL (>50 mcg/L) suggest acromegaly. Make sure that patient has been fasting. Emotional and physical stress may alter results. Indicate patient fasting status and recent activity level on the laboratory slip. Send blood sample to laboratory immediately.
Hypothalamus Although the Pituitary gland has been referred to as the "master gland," most of its functions rely on its interrelationship with the anterior pituitary. Two important groups of hormones from the hypothalamus are releasing hormones and inhibiting hormones. The function of these hormones is to either stimulate the release or inhibit the release of hormones from the anterior pituitary (Table 48-2). The hypothalamus also contains neurons, which receive input from the CNS, including the brainstem, limbic system, and cerebral cortex. -Neurons from the hypothalamus create a circuit to facilitate coordination of the endocrine system and autonomic nervous system (ANS). -In addition, the hypothalamus coordinates the expression of complex behavioral responses, such as anger, fear, and pleasure.
Pituitary- The pituitary gland (hypophysis) is located in the sella turcica under the hypothalamus at the base of the brain above the sphenoid bone (see Fig. 48-1). -The pituitary is connected to the hypothalamus by the infundibular (hypophyseal) stalk. -This stalk relays information between the hypothalamus and the pituitary. - The pituitary consists of two major parts, the anterior lobe (adenohypophysis) and the posterior lobe (neurohypophysis). - A smaller intermediate lobe produces melanocyte-stimulating hormone.
Anterior Pituitary (Adenohypophysis): 1.Growth hormone (GH), or somatotropin -All body cells -Promotes protein anabolism (growth, tissue repair) and lipid mobilization and catabolism. 2.Thyroid-stimulating hormone (TSH), or thyrotropin -Thyroid gland -Stimulates synthesis and release of thyroid hormones, growth and function of thyroid gland. 3. Adrenocorticotropic hormone (ACTH) -Adrenal Cortex -Fosters growth of adrenal cortex. Stimulates secretion of corticosteroids. 4. Gonadotropic hormones • Follicle-stimulating hormone (FSH) • Luteinizing hormone (LH)* Reproductive organs: -Stimulate sex hormone secretion, reproductive organ growth, reproductive processes. Melanocyte-stimulating hormone (MSH) -Melanocytes in skin -Increases melanin production in melanocytes to make skin darker. Prolactin: -Ovary and mammary glands in women -Testes in men -Stimulates milk production in lactating women. -Increases response of follicles to LH and FSH. Stimulates testicular function in men.
Posterior Pituitary (Neurohypophysis): Oxytocin -Uterus, mammary glands -Stimulates milk secretion, uterine contractility. Antidiuretic hormone (ADH), or vasopressin -Renal tubules, vascular smooth muscle -Promotes reabsorption of water, vasoconstriction.
Nervous System Control. In addition to chemical regulation, some endocrine glands are directly affected by the activity of the nervous system. - Pain, emotion, sexual excitement, and stress can stimulate the nervous system to modulate hormone secretion. - Neural involvement is initiated by the central nervous system (CNS) and implemented by the sympathetic nervous system (SNS). -For example, stress is sensed or perceived by the CNS with subsequent stimulation of the SNS. - The SNS secretes catecholamines that increase heart rate and blood pressure to deal with stress more effectively. (Effects of stress are discussed in Chapter 7.)
Rhythms. cortisol rises early in the day, declines toward evening, and rises again toward the end of sleep to peak by morning. GH, thyroid-stimulating hormone (TSH), and prolactin secretions peak during sleep. The menstrual cycle is an example of a body rhythm that is longer than 24 hours (ultradian). -These rhythms must be considered when interpreting laboratory results for hormone levels. (See diagnostic studies section in this chapter and Chapter 51.)
Regulation of Hormonal Secretion. mechanisms stimulate or inhibit hormone synthesis and secretion and include feedback, nervous system control, and physiologic rhythms.
Simple Feedback. 1.Negative feedback relies on the blood level of a hormone or other chemical compound regulated by the hormone (e.g., glucose). -It is the most common type of endocrine feedback system and results in the gland increasing or decreasing the release of a hormone. - Negative feedback is similar to the functioning of a thermostat in which cold air in a room activates the thermostat to release heat, and hot air signals the thermostat to prevent more warm air from entering the room. The pattern of insulin secretion is a physiologic example of negative feedback between glucose and insulin. -Elevated blood glucose levels stimulate the secretion of insulin from the pancreas. - As blood glucose levels decrease, the stimulus for insulin secretion also decreases. - The homeostatic mechanism is considered negative feedback because it reverses the change in blood glucose level. - Another example of Negative feedback is the relationship between calcium and parathyroid hormone (PTH). -Low blood levels of calcium stimulate the parathyroid gland to release PTH, which acts on bone, the intestine, and the kidneys to increase blood calcium levels. -The increased blood calcium level then inhibits further PTH release. 2.Positive feedback is also used to regulate hormone synthesis and release. -The female ovarian hormone estradiol operates by this type of feedback. - Increased levels of estradiol produced by the follicle during the menstrual cycle result in increased production and release of follicle-stimulating hormone (FSH) by the anterior pituitary. -FSH causes further increases in estradiol until the death of the follicle. This results in a drop of FSH serum levels. Thus with this type of feedback, rising hormone levels cause another gland to release a hormone that then stimulates further release of the first hormone. A mechanism for shutting off release of the first hormone (e.g., follicle death) is required or it will continue to be released. -Oxytocin= causes uterine contrations, when baby is in the birth canal ( look this up) 3.Complex feedback: 4. Rhythms:
Structures and Functions of Endocrine System: Glands: -Endocrine glands include: hypothalamus pituitary thyroid parathyroids adrenals pancreas ovaries testes pineal gland -Exocrine glands are not part of the endocrine system. -They secrete their substances into ducts that then empty into a body cavity or onto a surface. - For example, salivary glands produce saliva, which is secreted through salivary ducts into the mouth.
Structures and Functions of Endocrine System: Hormones- -Endocrine glands produce and secrete hormones that travel to affect their specific target tissues. -For example, the thyroid gland synthesizes the hormone thyroxine, which affects all body tissues. -Some hormones are released directly into the circulation, whereas others may act locally on cells where they are released and never enter the bloodstream. -This local effect is called paracrine action. -The action of sex steroids on the ovary is an example of paracrine action. Most hormones have common characteristics including: (1) secretion in small amounts at variable but predictable rates (2) regulation by feedback systems (3) binding to specific target cell receptors. -hormones help regulate the nervous system -catecholamines are hormones when they are secreted by the adrenal medulla, but act as neurotransmitters when secreted by nerve cells in the brain and peripheral nervous system. -When epinephrine, a catecholamine, travels through the blood, it is a hormone and affects target tissues. -When it travels across synaptic junctions, it acts as a neurotransmitter -the kidneys secrete erythropoietin -the heart secretes atrial natriuretic peptide, -the gastrointestinal (GI) tract secretes numerous peptide hormones (e.g., gastrin)
TABLE 48-3 GERONTOLOGIC ASSESSMENT DIFFERENCES: Endocrine System- Adrenal Cortex- -Adrenal cortex becomes more fibrotic and slightly smaller. -Decreased metabolism of cortisol. -Decreased plasma levels of adrenal androgens and aldosterone. -Decreased metabolic clearance rate for glucocorticoids.
TABLE 48-3 GERONTOLOGIC ASSESSMENT DIFFERENCES: Endocrine System Adrenal Medulla- -Increased secretion and basal level of norepinephrine. No change in plasma epinephrine levels. -Decreased responsiveness to β-adrenergic agonists and receptor blockers. Decreased β-adrenergic receptor response to norepinephrine. -May partly explain increased incidence of hypertension with aging.
TABLE 48-3 GERONTOLOGIC ASSESSMENT DIFFERENCES: Endocrine System- Pancreas- -Increase in fibrosis and fatty deposits in pancreas. - Increased glucose intolerance and decreased sensitivity to insulin. -May partly contribute to increased incidence of Diabetes Mellitus with advanced aging.
TABLE 48-3 GERONTOLOGIC ASSESSMENT DIFFERENCES: Endocrine System Gonads- Women: Decline in estrogen secretion. Women experience symptoms associated with menopause and have increased risk for atherosclerosis and osteoporosis. Men: Decline in testosterone secretion. Men may or may not experience symptoms. PTH, Parathyroid hormone; T3, triiodothyronine; T4, thyroxine; TSH, thyroid-stimulating hormone.
Anterior Pituitary. The anterior lobe accounts for 80% of the gland by weight and is regulated by the hypothalamus through releasing and inhibiting hormones. - These hypothalamic hormones reach the anterior pituitary through a network of capillaries known as the hypothalamus-hypophyseal portal system. -The releasing and inhibiting hormones in turn affect the secretion of six hormones from the anterior pituitary. Several hormones secreted by the Anterior pituitary are referred to as Tropic hormones. These are hormones that control the secretion of hormones by other glands. -Thyroid-stimulating hormone (TSH) stimulates the thyroid gland to secrete thyroid hormones. -Adrenocorticotropic hormone (ACTH) stimulates the adrenal cortex to secrete corticosteroids. - Follicle-stimulating hormone (FSH) stimulates secretion of estrogen and the development of ova in women and sperm in men. -Luteinizing hormone (LH) stimulates ovulation in women and secretion of sex hormones in both men and women. -In men LH is sometimes referred to as interstitial cell-stimulating hormone (ICSH). Growth hormone (GH) affects the growth and development of all body tissues. - It also has numerous biologic actions, including a role in protein, fat, and carbohydrate metabolism. -Prolactin stimulates breast development necessary for lactation after childbirth. -Prolactin is also referred to as a lactogenic hormone.
The following hormones from the hypothalamus target the anterior pituitary. Releasing Hormones • Corticotropin-releasing hormone (CRH) • Thyrotropin-releasing hormone (TRH) • Growth hormone-releasing hormone (GHRH), or somatotropin-releasing hormone • Gonadotropin-releasing hormone (GnRH) • Prolactin-releasing factor (PRF) Inhibiting Hormones • Somatostatin (inhibits growth hormone release) • Prolactin-inhibiting factor (PIF)
Thyroid Gland: The thyroid gland is located in the anterior portion of the neck in front of the trachea. -It consists of two encapsulated lateral lobes connected by a narrow isthmus (Fig. 48-8). -The thyroid gland is a highly vascular organ, and its size is regulated by TSH from the anterior pituitary. -The three hormones produced and secreted by the thyroid gland are thyroxine (T4), triiodothyronine (T3), and calcitonin.
Thyroxine and Triiodothyronine. Thyroxine (T4) accounts for 90% of thyroid hormone produced by the thyroid gland. -However, triiodothyronine (T3) is much more potent and has greater metabolic effects. -About 20% of circulating T3 is secreted directly by the thyroid gland, and the remainder is obtained by peripheral conversion of T4. - Iodine is necessary for the synthesis of both T3 and T4. These two hormones affect metabolic rate, caloric requirements, oxygen consumption, carbohydrate and lipid metabolism, growth and development, brain function, and other nervous system activities. - More than 99% of thyroid hormones are bound to plasma proteins, especially thyroxine-binding globulin synthesized by the liver. - Only the unbound "free" hormones are biologically active. -Thyroid hormone production and release is stimulated by TSH from the anterior pituitary gland. -When circulating levels of thyroid hormone are low, the hypothalamus releases thyrotropin-releasing hormone (TRH), which in turn causes the anterior pituitary to release TSH. -High circulating thyroid hormone levels inhibit the secretion of both TRH from the hypothalamus and TSH from the anterior pituitary gland.
Water deprivation (restriction) (ADH stimulation) Used to differentiate causes of diabetes insipidus (DI), including central DI, nephrogenic DI, and psychogenic polydipsia. ADH (vasopressin) is administered. Reference interval: In patients with central DI, urine osmolality increases after ADH. In patients with nephrogenic DI, no or minimal response to ADH. CAUTION: Patient is NPO for test. Severe dehydration may occur with central or nephrogenic DI during this test. Should be performed only if serum sodium is normal and urine osmolality is <300 mOsm/kg. Obtain baseline weight and urine and plasma osmolality. Assess urine hourly for volume and specific gravity. -Send hourly urine samples to laboratory for osmolality determination. Send blood samples for sodium and osmolality every 2 hr. Discontinue test and rehydrate if patient's weight drops >2 kg at any time. Rehydrate with oral fluids. -Check orthostatic BP and pulse after rehydration to ensure adequate fluid volume.
look at radiologic studies and thyroid studies (blood) page 1148, 1149 what does U-100 mean? (insulin syringes) answer: for every 1 mL there are 100 units of insulin drawing up insulin from 2 vials: 1. Air in cloudy (nph) 2. Air in Clear (regular) 3. draw insulin (regular 4. draw insulin (cloudy) *** draw up regular first because... rapid or short acting insulin binds w/ intermediate acting insulin which reduces the action of teh faster acting insulin, administer mixture w/in 5 minutes of preparing it.
