PrepU Chapter 40

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.

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 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.

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.

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.

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.

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 hormone is secreted based on a cyclic rather than a diurnal manner?

Follicle-stimulating hormone (FSH) Explanation: Hormone secretion varies widely over a 24-hour period. Some hormones, such as GH and adrenocorticotropic hormone (ACTH), have diurnal fluctuations that vary with the sleep-wake cycle. Others, such as the female sex hormones (e.g., follicle-stimulating hormone [FSH]) are secreted in a complicated cyclic manner. The levels of hormones such as insulin and antidiuretic hormone (ADH) are regulated by feedback mechanisms that monitor substances such as glucose (insulin) and water (ADH) in the body. The levels of many of the hormones are regulated by feedback mechanisms that involve the hypothalamic-pituitary-target cell system.

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.

Release and synthesis of anterior pituitary hormones are mainly regulated by which part of the body?

Hypothalamus Explanation: The hypophysis (pituitary plus hypothalamus) and hypothalamus stimulatory hormones regulate the release and synthesis of anterior pituitary hormones. The adrenal gland and thymus gland hormones are regulated by the hypothalamus. Cell receptors are involved with the target cell response to the hormones.

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.

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.

A hormone has been synthesized in the rough endoplasmic reticulum of an endocrine cell after which it has moved into the Golgi complex, been packaged in a vesicle, and been released into circulation. Which hormone is synthesized and released in this manner?

Insulin Explanation: Insulin is a peptide hormone; as such, its synthesis and release are vesicle mediated. Glucocorticoids (such as cortisol), androgens (such as testosterone), and estrogens are synthesized by non-vesicle-mediated pathways.

Hormones that cause the subsequent stimulation or release of another hormone, such as thyroid-stimulating hormone, typically belong to which structural classification?

Peptide proteins and glycoproteins Explanation: Hormones whose effect includes the stimulation and release of other hormones belong to the structural category of peptide proteins and glycoproteins.

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.

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.

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.

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.

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).

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.

Hormones can be synthesized by both vesicle-mediated pathways and non-vesicle-mediated pathways. What hormones are synthesized by non-vesicle-mediated pathways?

Androgens and estrogens Explanation: Hormones that are synthesized by non-vesicle-mediated pathways include the glucocorticoids, androgens, estrogens, and mineralocorticoids—all steroids derived from cholesterol.

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.

The vesicle-mediated pathway has a role in synthesis and release of which hormones? Select all that apply.

Dopamine Follicle-stimulating hormone Antidiuretic Hormone

A nurse assessing an 8-year-old child notes that the child is 6 feet tall. Which diagnostic test will be performed to evaluate the cause of the condition?

Glucose load Explanation: Endocrine testing may include urine collection, blood levels, or tests of stimulation or suppression. A child exhibiting signs of gigantism requires the glucose load test. If the pituitary responds correctly, the GH level will drop. If there is a secreting tumor, the GH level will increase.

While teaching a science class, the instructor mentions that both autocrine and paracrine hormonal actions occur without entering the bloodstream. A student asks, "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.

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.

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.

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.

The kidney produces 1,25-dihydroxyvitamin D. This form of vitamin D is responsible for which action in the body?

Stimulates calcium absorption from the intestine Explanation: 1,25-dihydroxyvitamin D from the kidney stimulates calcium absorption from the intestine. Somatostatin from the pancreas delays intestinal absorption of glucose. Thyroxine (T4) can increase metabolic rate. Growth hormone (GH) stimulates growth of bone and muscle.

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.

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.

The nurse is caring for a client with a hormonal disorder that is widely affecting many body systems. The nurse recognizes that which form of hormone signalling pathway is most likely involved in the client's disorder?

endocrine Explanation: The endocrine pathway involves hormones being produced, secreted, and traveling through blood vessels to distant cells to have an effect, thus having the potential to affect entire body systems. In the paracrine pathway hormones are produced in a cell, secreted, and act directly on nearby receptive cells. The autocrine pathway is similar to the paracrine pathway except that the receptor cells are also secretory cells meaning the cell is able to produce the hormone and exert an effect on itself. There is no pathway known as local mediation.

The endocrine system is closely linked with the nervous system. Which neurotransmitter can also act as a hormone?

epinephrine Explanation: Neurotransmitters such as epinephrine can act as neurotransmitters or as hormones and are referred to as neurohormones. Other examples include dopamine, oxytocin, and somatostatin. Thyroid stimulating hormone, progesterone, and norepinephrine do not act as neurotransmitters.

Which physiologic process best exemplifies a positive feedback mechanism?

increase in prolactin secretion that occurs with more frequent breastfeeding Explanation: A positive feedback mechanism occurs when one hormonal or physiologic factor stimulates further hormonal release, creating a cascade that will increase until the stimulus is reduced. Because the stimulation of breastfeeding releases prolactin that enhances milk production, this is a positive feedback mechanism. Correction of alterations in homeostasis is normally achieved using negative feedback mechanisms, such as those accomplished by insulin, parathyroid hormone, and antidiuretic hormone. In each of these cases, the stimulus results in an response that causes an opposite physiologic effect. For example, high blood glucose levels stimulate the release of insulin which then results in a lowering of the blood glucose 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 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.

The nurse is teaching a client who has been newly diagnosed with hypothyroidism about the function of the thyroid. Which statement about the role of the thyroid gland is most accurate?

The thyroid gland is responsible for increasing the metabolic rate. Explanation: The thyroid gland produces thyroid hormones, T3 and T4. These hormones increase the metabolic rate; increase protein and bone turnover; increase responsiveness to catecholamines; are necessary for fetal and infant growth and development. The parathyroid gland regulates calcium metabolism. The adrenal glands regulate "flight or fight" and the testes or ovaries regulate development of secondary sex characteristics.

A client experiences an increase in thyroid hormone as a result of a thyroid tumor. Which hormonal response demonstrates the negative feedback mechanism?

decreased thyroid-stimulating hormone (TSH) 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, TSH, which is manufactured by the anterior pituitary gland, would normally stimulate release of thyroid hormones. When there is an excess of thyroid hormones present, there should be a reduction in TSH levels (i.e., there is no need to stimulate more thyroid hormone production when there is already an excess present). The other hormones listed do not have a negative feedback relationship with thyroid hormone production.

Which statement best explains the function of hormone receptors?

Hormone receptors recognize a specific hormone and translate the hormonal signal into a cellular response. Explanation: Hormone receptors are complex molecular structures that are located either on the surface of or inside target cells. The function of these receptors is to recognize a specific hormone and translate the hormonal signal into a cellular response.

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 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.

For which endocrine disorders would autoimmune antibody testing be appropriate? Select all that apply.

Type 1 diabetes mellitus Graves disease Hypoparathyroidism Addison disease Explanation: Autoantibody testing is most commonly used for autoimmune disorders such as Hashimoto thyroiditis, type 1 diabetes mellitus, Graves disease, hypoparathyroidism, and Addison disease.

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.

The nurse is teaching a client newly diagnosed with hypothyroidism. The nurse teaches that thyroid hormone is transported by which?

protein carriers 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 client is scheduled for a suppression test as part of the diagnostic testing for his suspected endocrine disorder. The results of this test will help the care team determine:

whether the client is producing excessive hormone levels. Explanation: Suppression tests are used when hyperfunction of an endocrine organ is suspected. Suppression tests are not used to gauge pituitary or hypothalamus function. Stimulation tests are used to rule out hypofunction of an endocrine organ.