Patho PrepU Ch.40 (Mechanisms of Endocrine Control)

The physician suspects a client may be experiencing hypofunction of an endocrine organ. Select the most appropriate test to determine organ function.

Stimulation tests Explanation: Stimulation tests are used when hypofunction of an endocrine organ is suspected. Suppression tests are used when hyperfunction of an endocrine organ is suspected. Genetic testing is used for DNA analysis, and imaging may be used as a follow-up after the diagnosis.

After having a very stressful day in pathophysiology class, the student knows that which hormone (secreted by the adrenal cortex) will help decrease the effects of stress?

Cortisol, a glucocorticoid Explanation: Glucocorticoids, mainly cortisol, affect metabolism of all nutrients; regulate blood glucose levels; affect growth; have anti-inflammatory action; and decrease effects of stress. The other hormones do not affect stress levels.

When trying to explain hypothyroidism to a newly diagnosed client, the nurse stresses the fact that the thyroid hormone is transported in blood by specific:

Proteins Explanation: Some hormones, such as steroids and thyroid hormone, are bound to protein carriers for transportation to the target cell destination. The extent of carrier binding influences the rate at which hormones leave the blood and enter the cells. Cholesterol is a precursor for steroid hormone. Prohormones have an extra amino acid and are converted to hormones in the Golgi complex.

A nurse who works in the office of an endocrinologist is orienting a new staff member. Which teaching point should the nurse include in the orientation?

"A single hormone can act on not only one process or organ but often on several different locations or processes." Explanation: A single hormone can exert various effects in different tissues, or conversely, a single function can be regulated by several different hormones. Hormones act both distantly from their source and more locally, as in the case of autocrine and paracrine actions. Hormones are normally present at all times.

A client is admitted for ketoacidosis. The client's breath is fruity and others state that the client has been acting "different." Initial blood glucose level is 642 mg/dL (35.63 mmol/L). Which rationale for prescribing an insulin drip (IV infusion) is most accurate?

A lower pH of the body fluids (ketoacidosis) reduces insulin binding. Explanation: The affinity of receptors for binding hormones is also affected by a number of conditions. For example, the pH of the body fluids plays an important role in the affinity of insulin receptors. In ketoacidosis, a lower pH reduces insulin binding. While lowering the blood glucose level, potassium can be shifted from the extracellular to intracellular compartment, resulting in hypokalemia. Neurologic status does not cause vasoconstriction of vessels or poor absorption of subcutaneous injections.

Cyclic adenosine monophosphate (cAMP) performs which role in the functioning of the endocrine system?

Acting as a second messenger to mediate hormone action on target cells Explanation: cAMP is one of the most common second messengers, whose role is to generate an intracellular signal in response to cell surface receptor activation by a hormone. cAMP does not mediate hormone synthesis, act as a receptor itself, or inactivate hormones.

The nurse is assessing a client with thyrotoxicosis and the nurse is explaining how the thyroid gland is stimulated to release thyroid hormones. The nurse should describe what process?

Action of releasing hormones from hypothalamus Explanation: The synthesis and release of anterior pituitary hormones are largely regulated by the action of releasing or inhibiting hormones from the hypothalamus, which is the coordinating center of the brain for endocrine activity such as thyroid activity. There are no direct innervations for hormone release from the thyroid gland, and homeostatic receptors do not exist. Steady-state release of hormones does not occur.

Select the category of hormones that include norepinephrine and epinephrine.

Amines and amino acids Explanation: Hormones can be divided into three categories: (1) amines and amino acids; (2) peptides, polypeptides, proteins, and glycoproteins; and (3) steroids. The amines include norepinephrine and epinephrine. The second category, the peptides, includes polypeptides, proteins, and glycoproteins. The third category consists of the steroid hormones, which are derivatives of cholesterol.

When discussing luteinizing hormone and follicle-stimulating hormone with students, the instructor will emphasize that these hormones are under the control of:

Anterior pituitary gland Explanation: The pituitary gland has been called the master gland because its hormones control the functions of many target glands and cells. The anterior pituitary gland or adenohypophysis contains five cell types: (1) thyrotrophs, which produce thyrotropin, also called TSH; (2) corticotrophs, which produce corticotropin, also called ACTH; (3) gonadotrophs, which produce the gonadotropins, LH, and FSH; (4) somatotrophs, which produce GH; and (5) lactotrophs, which produce prolactin.

To prevent the accumulation of hormones in our bodies, the hormones are constantly being metabolized and excreted. Where are adrenal and gonadal steroid hormones excreted?

Bile and urine Explanation: Unbound adrenal and gonadal steroid hormones are conjugated in the liver, which renders them inactive, and then excreted in the bile or urine. Adrenal and gonadal steroid hormones are not excreted in the feces, cell metabolites, or the lungs.

The nurse is planning to collect a 24-hour urine sample for hormone assay. In which situation does the nurse collaborate with the health care provider to find an alternate type of testing?

Client has anuria. Explanation: The advantages of a urine test include the relative ease of obtaining urine samples and the fact that blood sampling is not required. The disadvantage is that reliably timed urine collections often are difficult to obtain and rely on adequate renal function. Anuria refers to the absence of urine output.

A client experiences an increase in cortisol as a result of Cushing disease. Which hormonal responses demonstrate the negative feedback mechanism?

Decreased adrenocorticotropic hormone (ACTH) Explanation: Negative feedback occurs when secretion of one hormone causes a reduction in the secretion of the hormone that stimulates production of the first hormone. In this case, ACTH manufactured by the anterior pituitary gland would normally stimulate the release of cortisol, but with the increase of cortisol produced by the secreting tumor, enough cortisol already floods the system that there should be a reduction in the ACTH level.

When hypofunction of an endocrine organ is suspected, which type of diagnostic test can be administered to measure and assess target gland response?

Hormone stimulation Explanation: Stimulating hormone can be given to identify (determine hypofunction) if the target gland is able to increase hormone response to increased stimulation. Agglutination with enzymes is a way of measuring hormone antigen levels. The 24-hour urine sample measures hormone metabolite excretion. Radioactive hormone-antibody binding levels provide a method of measuring plasma levels.

A health care provider is assessing a client for a potential endocrine disorder. Assessment findings identify abnormalities with emotion, pain, and body temperature. Which mechanism of endocrine control will require further laboratory/diagnostic assessment?

Hypothalamus Explanation: The hypothalamus is the coordinating center of the brain for endocrine, behavioral, and autonomic nervous system function. It is at the level of the hypothalamus that emotion, pain, body temperature, and other neural input are communicated to the endocrine system. The anterior pituitary regulates several physiologic processes, including stress, growth, reproduction, and lactation. The cerebellum is involved in motor control, and the cerebral cortex is associated with sensory, motor, and association.

An infant whose mother had myxedema during the pregnancy has failed to meet standards for growth and is developmentally delayed. Which hormonal imbalance is this child exhibiting?

Hypothyroidism Explanation: Thyroid hormone is necessary for metabolism at all ages, as well as growth and development during childhood. Uncorrected thyroid insufficiency in childhood leads to cretinism, a condition with marked physical and intellectual disability. Myxedema is the term used for thyroid insufficiency in adults.

An adult client is scheduled for testing of a suspected growth hormone (GH)-secreting tumor. Which result from the glucose suppression test would confirm the condition?

Increased GH secretion Explanation: A suppression test is intended to determine if an organ that is oversecreting will respond to feedback to suppress that hormone. The glucose suppression test is used for an adult with acromegaly from excessive GH production. Normally, glucose would cause a decrease in GH secretion, but there is increased production of GH in response to the glucose in the test when the client has acromegaly.

The nurse is discussing positive feedback mechanisms. Which example best explains this mechanism?

Increased estradiol production causes increased follicle-stimulating hormone (FSH) production. Explanation: The positive feedback mechanism regulates hormones as follows: a rising level of a hormone causes another gland to release a hormone that is stimulating to the first. The other choices represent negative feedback mechanisms of control.

While teaching a science class, the instructor mentions that both autocrine and paracrine hormonal actions occur without entering the bloodstream. A student aks, "What cells do paracrine actions affect?" Which response is correct?

Local Explanation: Paracrine actions are hormonal interactions with local cells other than those that produce the hormone; autocrine actions are with self-cells (cells from which they were produced). Both autocrine and paracrine hormonal actions affect target cells. Neither paracrine nor autocrine actions affect cell storage.

A nursing instructor is teaching a group of students about the action of hormones. The instructor determined that teaching was effective when the students recognize the local action of hormones as:

Paracrine Explanation: When hormones act locally on cells other than those that produced the hormone, the action is called paracrine. Hormones can also exert an autocrine action on the cells in which they were produced. Pancreatic and hormonal are not actions.

Which gland is often referred to as the master gland because it secretes many hormones?

Pituitary Explanation: The pituitary gland has been called the master gland because its hormones control the functions of many target glands and cells. That is not a term used to refer to the other options.

Which structure controls the functions of the greatest number of target glands and cells?

Pituitary gland Explanation: The pituitary gland has been called the master gland because its hormones control the functions of many target glands and cells. It supersedes the importance of the thyroid, adrenal cortex, or pancreas in this regulatory role.

As part of maintaining homeostasis, why are hormones, secreted by endocrine cells, continuously inactivated?

Prevent accumulation Explanation: Continuous inactivation of secreted hormones is necessary to prevent accumulation that could disrupt the feedback mechanism. Increased secretion stimulates production of more receptor sites. Metabolic waste absorption is not a function of the endocrine system.

A client with a history of brain tumors that resulted in partial removal of the pituitary gland years ago expresses concern to the health care provider about whether she will be able to breast-feed her infant. Which physiologic function of the pituitary gland facilitates breast milk production?

Prolactin Explanation: The anterior pituitary gland or adenohypophysis contains five cell types: (1) thyrotrophs, which produce thyrotropin, also called TSH; (2) corticotrophs, which produce corticotropin, also called ACTH; (3) gonadotrophs, which produce the gonadotropins, LH and FSH; (4) somatotrophs, which produce GH; and (5) lactotrophs, which produce prolactin that is involved with breast growth and milk production.

Hormones are chemical messengers that provide which function in the body?

Regulate body functions Explanation: Hormones regulate and integrate body functions. Hormones act on specific target cells, but they cause a variety of effects on tissues. Hormones do not transport other substances; hormones are transported and present in body fluids at all times.

A nurse caring for a client who has undergone an antithyroid peroxidase (anti-TPO) antibody test with elevated results should be prepared to educate the client about which disease process?

ashimoto thyroiditis Explanation: Diagnosis of Hashimoto thyroiditis is usually made by detecting elevated levels of anti-thyroid peroxidase antibodies (TPOAb) in the serum. Gigantism is diagnosed as an excessive secretion of growth hormone. There may be high levels of insulin-like growth factor 1 (IGF-1), which also stimulates excessive skeletal growth. States of hyperparathyroidism are associated with increased levels of 1,25-(OH)2D3. Parathyroid hormone (PTH) is an important regulator of calcium and phosphate levels in the blood. Diabetes is diagnosed following fasting plasma glucose test level of 126 mg/dL (6.99 mmol/L) or greater. Glycated hemoglobin testing (Hemoglobin A1C) is a test that measures the quantity of a subtype of hemoglobin that has been glucated, meaning glucose molecules have become bound to the hemoglobin molecule. In conditions of hyperglycemia, the A1C level is increased.

A client has developed a tumor of the posterior pituitary gland. The client is at risk for problems with secretions of:

Antidiuretic hormone (ADH) and oxytocin Explanation: The posterior pituitary secretes ADH and oxytocin/vasopressin, while the anterior pituitary secretes the hormones listed in the other choices.

When hormones act locally rather than being secreted into the bloodstream, their actions are termed:

Autocrine and paracrine Explanation: When hormones act locally on cells other than those that produced the hormone, the action is called paracrine. Hormones also can exert an autocrine action on the cells from which they were produced.

Which type of imaging is preferred to evaluate the bone density of a client with hyperparathyroidism?

Dual energy x-ray absorptiometry (DXA) scan Explanation: Preferred types of scans for endocrine tissues include MRI of the pituitary gland and hypothalamus, CT scan of the adrenal glands, DXA scan of bone density, and ultrasound of possible nodules of the thyroid gland. Bone density may be decreased in a client with hyperparathyroidism.

A nurse examines the laboratory values of a client in heart failure. Which value indicates a compensatory hormone mechanism?

Elevated atrial natriuretic hormone Explanation: In heart failure, the client experiences fluid backlog in the heart as venous blood continues to return, but cardiac output is reduced. This stretches the atria, which secrete atrial natriuretic hormone (or peptide) to stimulate vasodilation and increased renal excretion of sodium and water. This reduces the volume and the strain in the heart.

Which manifestation would the nurse observe when assessing a client diagnosed with a benign secreting tumor of the adrenal medulla?

Elevated catecholamine levels and tachycardia Explanation: The adrenal medulla secretes the neurotransmitters epinephrine (adrenalin) and norepinephrine (a precursor to epinephrine). A secreting tumor will cause the client to experience manifestations of sympathetic stimulation, such as episodic anxiety, tachycardia, and hypertension. A tumor of the adrenal medulla will not impact thyroid or aldosterone secretion.

Which physiologic process allows hormones to exert influence upon some cells and not others?

Hormone receptors Explanation: Hormone receptors are complex molecular structures (usually proteins) that are located either on the cell surface or inside target cells. The structure of these receptors is specific to a particular hormone, which allows target cells to respond to one hormone and not to others. For example, receptors in the thyroid are specific for thyroid-stimulating hormone, and receptors on the gonads respond to the gonadotropic hormones. Positive feedback control occurs when rising levels of a hormone cause another gland to release a hormone that is stimulating to the first. Protein binding describes the ability of proteins to form bonds with other substances. Pituitary-hypothalamic feedback describes negative feedback.

Which gland acts as a signal-relaying bridge between multiple body systems and the pituitary gland?

Hypothalamus Explanation: The activity of the hypothalamus is regulated by both hormonally mediated signals (e.g., negative feedback signals) and by neuronal input from a number of sources. Neuronal signals are mediated by neurotransmitters such as acetylcholine, dopamine, norepinephrine, serotonin, gamm-aminobutyric acid (GABA), and opioids. Cytokines that are involved in immune and inflammatory responses, such as the interleukins, also are involved in the regulation of hypothalamic function. This is particularly true of the hormones involved in the hypothalamic-pituitary-adrenal axis. Thus, the hypothalamus can be viewed as a bridge by which signals from multiple systems are relayed to the pituitary gland. This cannot be said of the other options.

What is the most common mechanism of hormone control?

Negative feedback Explanation: With negative feedback, the most common mechanism of hormone control, some feature of hormone action directly or indirectly inhibits further hormone secretion so that the hormone level returns to an ideal level or set point.

Several hormones, including growth hormone (GH) and thyrotropin-releasing hormone (TRH), are bound to and carried by which substance?

Proteins Explanation: Some hormones, such as steroids and thyroid hormone, are bound to protein carriers for transportation to the target cell destination. Cholesterol is a precursor for steroid hormone. Prohormones have an extra amino acid and convert to hormones in the Golgi complex.

Select the most accurate statement regarding measurements of urinary hormone.

Provide a better measure of hormone levels during a designated period. Explanation: Measurements of urinary hormone or hormone metabolite excretion often are done on a 24-hour urine sample and provide a better measure of hormone levels during that period than hormones measured in an isolated blood sample. The advantages are relative ease of obtaining urine samples and blood sampling is not required. The disadvantages are that timed urine collections often are difficult to obtain and urine samples may be accidentally discarded or inaccurately preserved; drugs or disease states that alter hormone metabolism may interfere with the test results.

A client has received an injection containing thyrotropin-releasing hormone (TRH) and is now being assessed for serum levels of thyroid-stimulating hormone (TSH). Which type of diagnostic testing is this client undergoing?

Stimulation testing Explanation: Introduction of TRH tests the pituitary gland's ability to produce TSH, and is an example of a stimulation test. Suppression testing examines a gland's response to a stimulus that would normally result in decreased hormone production. RIA and autoantibody testing are examples of direct and indirect measurement of serum levels of a hormone.

The nurse is caring for a client with decreased serum protein levels secondary to liver failure. When administering medications that are highly protein bound, the nurse anticipates the resulting drug level will respond in which of these ways?

The drug level will be elevated as lack of protein allows more free drug to circulate. Explanation: Peptide hormones and protein hormones usually circulate unbound in the blood. Specific carrier proteins synthesized in the liver carry steroid hormones and thyroid hormone, for example. Drugs that compete with a hormone for binding with transport carrier molecules increase hormone action by increasing the availability of the active unbound hormone.

A client undergoing an evaluation of hormone levels asks, "What regulates the hormone levels?" Which response by the nurse would be considered most accurate?

The hypothalamic-pituitary-target cell system Explanation: The levels of many of the hormones are regulated by feedback mechanisms that involve the hypothalamic-pituitary-target cell system. Positive feedback control refers to rising levels of a hormone that causes another gland to release a hormone that is stimulating to the first. The hypophyseal portal system connects the supraoptic and paraventricular nuclei of the hypothalamus with the posterior pituitary gland. Exogenous forms of hormones (given as drug preparations) can influence the normal feedback control of hormone production and release.

A client with many nonspecific complaints has been ordered a positron emission tomography (PET) scanning for evaluation of:

tumors located on the endocrine glands. Explanation: Positron emission tomography (PET) scanning is being used more widely for evaluation of endocrine tumors. PET scans do not calculate the pancreas response to insulin. A DEXA is used for diagnosis and monitoring of osteoporosis (bone density). Isotopic imaging includes radioactive scanning of the thyroid (using radioiodine) and parathyroids.

In major athletic competition, athletes are required to submit to liquid chromatography testing looking for:

use of performance-enhancing agents to increase the chances of winning. Explanation: For some steroid or peptide hormones, mass spectrometry is becoming increasingly useful and can be combined with other analytical techniques, such as liquid chromatography. These approaches provide definitive identification of the relevant hormone or compound according to its chemical or physical characteristics (e.g., unequivocal detection of performance-enhancing agents in sports).

An adult client presents to the emergency department after an episode of syncope. Blood pressure is low and the pulse is thready and rapid. The client frequently voids large amounts of pale, clear urine. Lung sounds are clear and skin turgor is inelastic. Which endocrine disorder is the likely cause of these manifestations?

Diabetes insipidus Explanation: Normally, antidiuretic hormone (ADH) from the posterior pituitary gland causes the renal tubule to reabsorb water and sodium. When too little ADH is secreted, the client will lose large amounts of fluid and become dehydrated. Despite fluid volume deficit, the urine output will be dilute and in large amounts. In hyperparathyroidism, the client will have an elevated blood calcium level and cardiac dysrhythmias. Fluid volume will remain stable, but the client may develop renal calculi. In myxedema, lack of thyroid hormones causes the client to become sluggish. Urinary output remains normal. Gigantism results from excess production of growth hormone in children and results in large body size. It does not influence urine output.

Which hormone is produced by the anterior pituitary gland?

Growth hormone (GH) Explanation: GH is among the hormones produced and released by the anterior pituitary. Oxytocin is a posterior pituitary hormone, whereas CRH is produced by the hypothalamus. Norepinephrine and epinephrine are produced by the adrenal medulla.

Which gland acts as a signal relaying bridge between multiple body systems and the pituitary gland?

Hypothalamus Explanation: The activity of the hypothalamus is regulated by both hormonally mediated signals (e.g., negative feedback signals) and by neuronal input from a number of sources. Neuronal signals are mediated by neurotransmitters such as acetylcholine, dopamine, norepinephrine, serotonin, gamma-aminobutyric acid (GABA), and opioids. Cytokines that are involved in immune and inflammatory responses, such as the interleukins, also are involved in the regulation of hypothalamic function. This is particularly true of the hormones involved in the hypothalamic-pituitary-adrenal axis. Thus, the hypothalamus can be viewed as a bridge by which signals from multiple systems are relayed to the pituitary gland. This cannot be said of the other options.

A client receives steroids for several months to treat an inflammatory condition. Which action by the primary health care provider indicates an understanding of the negative feedback mechanism when the client no longer needs the medication?

Prescribing a tapering dose of the medication over weeks Explanation: Negative feedback occurs when secretion of one hormone causes a reduction in the secretion of the hormone that stimulates production of the first hormone. In this case, adrenocorticotropic hormone (ACTH) manufactured by the anterior pituitary would normally stimulate release of cortisol, but with the increase of cortisol produced by the secreting tumor, enough cortisol already floods the system that there should be a reduction in the ACTH level. Sudden withdrawal of the medication would leave the client without glucocorticoids and risk an Addisonian crisis. Gradual withdrawal of the medication allows the pituitary to measure the drop in cortisol levels and begin secreting ACTH.

Which manifestation would a nurse expect when assessing a child with insufficient growth hormone (GH) secretion?

Rank below 10% on the growth chart Explanation: GH stimulates growth of bone and muscle and promotes protein synthesis and fat metabolism and decreased carbohydrate metabolism. A child lacking sufficient GH would demonstrate lack of growth but not the mental delays seen in childhood hypothyroidism.

Hormones exert their action by interacting with which type of receptors?

Affinity Explanation: Target cell response varies with the number and affinity of the relevant receptors. The structure variations allow target cells to respond to one hormone and not to others. Cell membrane permeability can affect transmission; ion transport allows hormones to enter the cell. Hormone receptors are complex molecular structures (usually proteins not fats like cholestrol) that are located either on the cell surface or inside target cells. Antibodies may destroy or block the receptor proteins.

The nurse is educating a client with a newly diagnosed thyroid cancer. Which testing procedure should be reviewed because it allows good examination of the tissue structure and provides information about the tissue function as well?

Positron emission tomography/CT (PET/CT) Explanation: PET/CT imaging is advantageous in that the CT component allows a good examination of the tissue structure, whereas the PET component provides information about tissue function. PET/CT has been demonstrated to be useful in managing thyroid cancers. DEXA scan is routinely used for the diagnosis and monitoring of osteoporosis and metabolic bone imagining. Ultrasonography scanning provides good structural imaging and is used frequently to aid in visualization of a lesion for biopsy. MRI provides information about structural changes within solid tissue.

How long is the half-life of the hormone aldosterone, which is only 15% protein bound?

25 minutes Explanation: Aldosterone, which is only 15% protein-bound, has a half-life of only 25 minutes. The higher the percentage of protein binding, the longer the half-life will be.

The release of insulin from the pancreatic beta cells can inhibit further release of insulin from the same cells. This is an example of which type of hormone action?

Autocrine Explanation: Hormones can exert autocrine action on the cells from which they were produced. Retinoids are compounds with hormone-like actions. Juxtacrine action involves a chemical messenger imbedded in a plasma membrane that interacts with a specific receptor on a juxtaposed cell. Arachidonic acid is a precursor for eicosanoid compounds (similar to retinoids).

A middle-aged female client has been diagnosed with a thyroid condition. The nurse educates the client about the prescription and needed follow-up lab work, which will help regulate the dosage. The client asks, "Why do I not return to the clinic for weeks, since I am starting the medication tomorrow morning?" The nurse bases the answer on the knowledge that thyroid hormones:

may take days for the full effect to occur, based on the mechanism of action. Explanation: Hormones produce their effects through interaction with high-affinity receptors, which in turn are linked to one or more effector systems within the cell. These mechanisms involve many of the cell's metabolic activities, ranging from ion transport at the cell surface to stimulation of nuclear transcription of complex molecules. The rate at which hormones react depends on their mechanism of action. Thyroid hormone, which controls cell metabolism and synthesis of intracellular signaling molecules, requires days for its full effect to occur. None of the other distractors are accurate reasons to have the client return to the clinic weeks after starting the medication.