Patho PrepU Chapter 31
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. Page 753
While reviewing the major actions of follicle-stimulating hormone (FSH), the faculty points out that in males, this hormone is responsible for the:
sperm production. Explanation: FSH in males stimulates sperm production. GH stimulates growth of bone and muscle. LH stimulates secretions of testosterone. Androgens affect the development of male sex organs. Page 756
In an adult with acromegaly, a growth hormone (GH)-secreting tumor is suspected. What diagnostic test would be used for this client?
A GH suppression test Explanation: A GH suppression test may be useful to confirm this situation. The other answers are incorrect. Page 764
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. Page 757
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 other answers are incorrect. Page 755
When hormones act locally rather than being secreted into the bloodstream, their actions are termed what?
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. The other terms are incorrect. Page 765
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. Page 757
The nurse is reviewing the test results of a client who was given thyrotropin-releasing hormone (TRH) to evaluate the function of the pituitary gland. The nurse would recognize pituitary dysfunction as:
Decreased TSH levels Explanation: Stimulation tests are used when hypofunction of an endocrine organ is suspected. Failure to increase TSH levels after a TRH stimulation test suggests an inadequate capacity to produce TSH by the pituitary (i.e., the pituitary is dysfunctional in some way). The other tests results would not increase. Page 756
A patient experiences an increase in cortisol as a result of Cushing's disease. Which of the following hormonal responses demonstrates 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. Page 762
A patient experiences an increase in thyroid hormone as a result of a thyroid tumor. Which of the following hormonal responses 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, but with the increase of those hormones by the secreting tumor, enough thyroid hormones flood the system that there should be a reduction in TSH levels. Page 764
A nurse examines the laboratory values of a patient in heart failure. Which of the following values indicates a compensatory hormone mechanism?
Elevated atrial natriuretic hormone Explanation: In heart failure, the patient 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. Page 754
Which of the following manifestations would the nurse observe when assessing a patient diagnosed with a pheochromocytoma 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 patient 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. Page 756
The hypophysis is a unit formed by the pituitary and the hypothalamus. These two glands are connected by the blood flow in what system?
Hypophyseal portal system Explanation: The hypothalamus and pituitary (i.e., hypophysis) form a unit that exerts control over many functions of several endocrine glands as well as a wide range of other physiologic functions. These two structures are connected by blood flow in the hypophyseal portal system, which begins in the hypothalamus and drains into the anterior pituitary gland, and by the nerve axons that connect the supraoptic and paraventricular nuclei of the hypothalamus with the posterior pituitary gland. The other answers are not correct. Page 762
An instructor is teaching the class about positive feedback mechanism. The best example would be:
Increased estradiol production causes increased gonadotropin (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. Page 762
A patient develops hypocalcemia after thyroid surgery. Which of the following hormonal imbalances caused this complication?
Lack of parathyroid hormone Explanation: The parathyroid glands are located on the posterior side of the thyroid gland. If the parathyroid glands are removed at the same time as the thyroid the patient will experience a drop in serum calcium levels. Page 756
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. Page 762
The hormone levels in the body need to be kept within an appropriate range. How is this accomplished for many of the hormones in the body?
Negative feedback loop Explanation: The level of many of the hormones in the body is regulated by negative feedback mechanisms. The other answers are incorrect. Page 762
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 also can exert an autocrine action on the cells in which they were produced. Pancreatic and hormonal are not actions. Page 754
While reviewing the concept of nuclear receptors with a group of pathophysiology students, the instructor uses the example of clients with type 2 diabetes mellitus taking pioglitazone, a thiazolidinedione medication. Because of the peroxisome proliferator-activated receptors (PPARs), the drug has which effect on the clients' diabetes? Select the best answer.
Promote glucose uptake and increase the synthesis of certain proteins involved in fat metabolism, which reduces levels of certain types of lipids. Explanation: The peroxisome proliferator-activated receptors (PPARs) bind intracellular lipid metabolites and regulate the transcription of genes involved in lipid metabolism and adipose tissue metabolism. Pioglitazone is not given solely to increase metabolic rate or to just burn fats, even though this may occur. Thiazolidimedione medications lower insulin resistance in muscle and fat. They also reduce glucose produced by the liver. Page 759
Select the process that allows hormones to exert influence upon some cells and not others.
Receptor binding Explanation: Receptor binding is a process that 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. Page 758
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 interestingal absorption of glucose. Thyroxine (T4) can increase metabolic rate. Growth hormone (GH) stimulates growth of bone and muscle. Page 756
A 21 year-old female is suspected of having inadequate function of her hypothalamic-pituitary-thyroid system. Her care provider is planning to inject thyrotropin-releasing hormone (TRH) and then measure her levels of TSH. Which of the following diagnostic tests is being performed?
Stimulation test Explanation: A stimulation test involves the introduction of an element that stimulates the production of another factor or hormone followed by measurement of that hormone. This is not the case in a suppression test, RIA test of metabolite excretion test. Page 764
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. Page 757
Which of the following statements best captures the relationship between the hypothalamus and the pituitary gland as it relates to endocrine function?
The hypothalamus receives input from numerous sources throughout the body and directs the pituitary to then control many target glands and cells. Explanation: The hypothalamus can be viewed as a bridge by which signals from multiple systems are relayed to the pituitary gland. The hypothalamus collects data from sources throughout the body rather than directly measuring levels and communication normally flows from the hypothalamus to the pituitary. Page 759
The nurse is teaching a client who has been newly diagnosed with hypothyroidism about the function of the thyroid. Which of these does the nurse explain to the client is the role of the thyroid gland?
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. Page 756
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. Page 764
A client with hyperthyroidism is being treated with medication that blocks the activity of thyroid-stimulating hormone. Her care team has determined that she has been overproducing TSH. This client will have lost her ability to:
have negative feedback regulation. Explanation: When the sensors detect a decrease in hormone levels, they initiate changes that cause an increase in hormone production; when hormone levels rise above the set point of the system, the sensors cause hormone production and release to decrease. Positive feedback increases activity rather than shuts if off. Metabolism of the hormone is not an issue in regulation. Page 759
A patient exhibiting problems with their thyroid has been scheduled for a radioactive scan. From the following list of patients, which would the nurse question as to whether this would be a safe procedure for this patient?
A young female patient who has been trying to get pregnant. Explanation: Radioactive iodine therapy is contraindicated in pregnant women because 131I crosses the placenta and can adversely affect the fetal thyroid gland. The other clients would have no contraindication to the substance. Page 765
Which of the following hormones are derivatives of cholesterol?
Aldosterone and testosterone Explanation: Steroids such as aldosterone and testosterone are a classification of hormones that are derived from cholesterol. Epinephrine and norepinephrine are both amino acids while insulin and glucagon and classified among peptides, polypeptides, proteins, and glycoproteins. Eicosanoids and retinoids consist of fatty acid compounds. Page 755
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 affects metabolism of all nutrients; regulates blood glucose levels, affects growth, has antiinflammatory action, and decreases effects of stress. The other hormones do not affect stress levels. Page 756
Which of the following types of imaging is preferred to evaluate the bone density of a patient with hyperparathyroidism?
Dual energy x-ray absorptiometry (DEXA) scan Explanation: Preferred types of scans for endocrine tissues include MRI of the pituitary gland and hypothalamus, CT scan of the adrenal glands, DEXA scan of bone density, and ultrasound of possible nodules of the thyroid gland. Bone density may be decreased in a patient with hyperparathyroidism. Page 765
A hypernatremic client is researching his condition and learns that aldosterone binds to an intracellular receptor. What do intracellular receptors generally stimulate in a cell?
Gene expression Explanation: Aldosterone is a lipid-soluble hormone that activates gene transcription factors in the cytosol. Most lipid-soluble hormones work in this way. Water-soluble hormones activate ion channel receptors, cAMP, and G-proteins. Page 759
An adult patient is scheduled for testing of a suspected growth hormone (GH)- secreting tumor. Which of the following results 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 patient has acromegaly. Page 764
Which of the following best describes the half-life of a highly protein bound drug such as thyroxine (99% protein bound)? The half-life would be:
Much longer to reduce the concentration of the hormone by one half. Explanation: The half-life of a hormone—the time it takes for the body to reduce the concentration of the hormone by one half—is positively correlated with its percentage of protein binding. Thyroxine, which is more than 99% protein bound, has a half-life of 6 days whereas Aldosterone, 15% bound, has a half-life of only 25 minutes. Page 757
Which of the following hormones will elicit a more rapid response than the others?
Norepinephrine Explanation: Neurotransmitter hormones open ion channels and produce extremely rapid responses, whereas peptides and proteins change cell metabolism over a period of days. Page 754
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. Page 761
Select the statement that best explains the function of hormone receptors.
Hormone receptors recognize a specific hormone and translate the 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. The other choices are not true. Page 760
Many hormones are measured for diagnostic reasons by using the plasma levels of the hormones. What is used today to measure plasma hormone levels?
Radioimmunoassay methods Explanation: Real progress in measuring plasma hormone levels came more than 40 years ago with the use of competitive binding and the development of radioimmunoassay methods. The other answers are incorrect. Page 764
Which of the following hormones cross cell membranes to connect to nuclear receptors? Select all that apply.
-Glucocorticoids -Thyroid hormones -Vitamin D Explanation: Steroids, Vitamin D, and thyroid hormone are fat soluble and they can cross the cell membrane where they connect to intracellular receptors that move to the nucleus and bind with receptors on the target gene. Page 761
When explaining about structural classifications to a group of students, the instructor discusses the peptides and proteins. They talk about small hormones and hormones as large and complex as growth hormone (GH) which has approximately how many amino acids involved?
200 amino acids. Explanation: Growth hormone is very large and complex protein which has ~ 200 amino acids. Page 754
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. Page 757
A client comes to a scheduled appointment in the endocrine clinic. The primary care physician referred the client, suspecting acromegaly. Knowing the usual testing involved, the nurse should educate the client about which lab/diagnostic procedure?
A suppression test Explanation: Suppression tests are used when hyperfunction of an endocrine organ is suspected. When an organ or tissue is functioning autonomously (i.e., is not responding to the normal negative feedback control mechanisms and continues to secrete excessive amounts of hormone), a suppression test may be useful to confirm the situation. For example, when a GH-secreting tumor is suspected, the GH response to a glucose load is measured as part of the diagnostic workup. Normally, a glucose load would suppress GH levels. However, in adults with GH-secreting tumors (a condition known as acromegaly), GH levels are not suppressed. Stimulation tests are used when hypofunction of an endocrine organ is suspected. The diagnosis of genetic diseases using DNA analysis is rapidly becoming a routine part of endocrine practice. Completion of the human genome sequence has revealed the presence of about 30,000 genes. The considerable interest in the field of genomics (i.e., examination of the DNA) and transcriptomics (i.e., examination of the mRNA) has been complemented by advances in proteomics. Brain scans may be advised after initial suppression testing if a tumor is suspected. Page 764
The number of hormone receptors on a cell may be altered for any of several reasons. The most appropriate response would be:
Antibodies may destroy or block the receptor proteins. Explanation: The number of hormone receptors on a cell may be altered for any of several reasons. Antibodies may destroy or block the receptor proteins. Increased or decreased hormone levels often induce changes in the activity of the genes that regulate receptor synthesis. Decreased hormone levels often produce an increase in receptor numbers by means of a process called up-regulation, increasing the sensitivity of the body to existing hormone levels. Sustained levels of excess hormone often bring about a decrease in receptor numbers by down-regulation, producing a decrease in hormone sensitivity. Page 758
While discussing the regulation of hormone levels, the instructor gives an example of hormones regulated by feedback mechanisms. Which example of this regulation is best?
Following a meal that was high in carbohydrates, a person's blood glucose elevates, which stimulates the release of insulin from the pancreas. Explanation: 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. None of the other examples are accurate examples of this feedback mechanism. Page 759
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. Page 764
A client who is referred to the endocrinologist's office for an evaluation of his hormone levels asks what regulates the hormone levels. The best response would be that hormone levels in the body are primarily regulated by:
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. Page 759
Sometimes the measurement of hormones is done through a urine sample. What is an advantage of measuring hormone levels through a urine sample rather than a blood sample?
Urine samples are easily obtaine 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 other answers are not true. Page 764
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. Page 762
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, ?-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. Page 759
Neurotransmitters like catecholamines (ex. dopamine and epinephrine) have a reaction time of:
Milliseconds. Explanation: The neurotransmitters, which control the opening of ion channels, have a reaction time of milliseconds. Page 753
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. Page 764
When caring for a client who is being screened for osteoporosis, the nurse plans to evaluate the results of which of theses diagnostic tests?
Dual-energy x-ray absorptiometry (DEXA) Explanation: Dual-energy x-ray absorptiometry (DEXA) is used routinely for the diagnosis and monitoring of osteoporosis and metabolic bone diseases. Page 765
A 38-year-old woman takes clomiphene, an infertility drug that works by competing with, and thereby blocking, cellular receptors for estrogen. Which of the following statements is most likely to be true of this client?
Estrogen will continue to pass freely through the cellular membranes. Explanation: Because estrogen is a steroid hormone, its receptors in target cells are located inside the cell membrane, and their blockage does not affect the movement of the hormone into and out of the cell. Receptors are specific for each hormone, so no hormones other than estrogen will be blocked. Up-regulation occurs when hormone levels are decreased, and in this case the estrogen level will increase. Second messengers, such as cAMP, are only activated by peptide hormones and catecholamines. Page 758
The physician is assessing a client with a preliminary diagnosis of endocrine disorder. Further assessment findings identify abnormalities with emotion, pain, body temperature, and neural input. The physician determines the need to further assess the:
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 physiological 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. Page 754
A patientreceives steroids for several months to treat an inflammatory condition. Which of the following actions by the primary healthcare provider indicates an understanding of the negative feedback mechanism when the patient 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 already floods the system there has been a reduction in ACTH levels. Sudden withdrawal of the medication would leave the patient 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. Page 762
The nurse administers a glucocorticoid medication to a client with pneumonia. Which of these does the nurse teach the client is the purpose of the medication?
To decrease airway inflammation Explanation: Glucocorticoids affect metabolism of all nutrients and have anti-inflammatory effects, which can assist with airway inflammation. Page 756
The nurse explains to a client in labor who has demonstrated ineffective contractions impeding progression of labor that the health care provider has added oxytocin infusion to the orders. Which of these does the nurse teach the client is the purpose of oxytocin?
To stimulate contraction of the uterus Explanation: The role of oxytocin is to stimulate contraction of the pregnant uterus and milk ejection from breasts after childbirth. An infusion of oxytocin will promote effective contractions. Page 756
A client with a history of an endocrine disorder exhibits signs and symptoms of hormone deficiency. Which of the following processes would the client's care team most likely rule out first as a contributing factor?
Up-regulation has increased the sensitivity of the body to particular hormone levels. Explanation: Up-regulation is a response to low hormone levels in which the number of receptors increases. As such, it would not likely result in signs and symptoms of deficiency but is rather a compensatory mechanism that counters a deficiency. Insufficient numbers of receptors, low affinity and down-regulation could all contribute to signs and symptoms of a hormone deficiency. Page 758
