Question 1

You are attending to your 51-year-old female patient who has come to you complaining that she is losing weight, yet is continuously hungry and eating more than usual. She also reports that she is experiencing irritability, insomnia, diarrhea, muscle weakness, heart palpitations, and intolerance to heat. You suspect your patient is suffering from Graves disease. Assay for which of the following in her blood would most likely confirm your diagnosis?
A) decreased growth hormone
B) decreased vasopressin
C) elevated insulin
D) insulin receptor autoantibodies
E) thyroid hormone receptor autoantibodies

Accepted Answer

Graves disease is an autoimmune disorder that leads to hyperthyroidism. It is characterized by the presence of thyroid-stimulating hormone receptor autoantibodies, which stimulate the thyroid gland to produce excess thyroid hormones.  Graves disease is the most common autoimmune disease, affecting 0.5% of the population in the United States, and represents 50% to 80% of cases of hyperthyroidism. The disorder occurs more commonly in women, smokers, and patients with other autoimmune diseases. Graves hyperthyroidism results from the production of autoantibodies that bind to and activate the thyroid-stimulating hormone (TSH) receptor on the surface of thyroid follicular cells. This activation stimulates follicular cell growth, causing diffuse thyroid enlargement and increased production of thyroid hormones.

Question 2

A 67-year-old postmenopausal woman is being examined by her physician due to back pain, an apparent loss of height, and the inability to stand erect. Her physician orders a spinal x-ray which shows vertebral thinning typical of osteoporosis. Which of the following hormones would be the most useful in attempting to treat this patient's condition?
A) ACTH
B) growth hormone
C) parathyroid hormone
D) thyroid hormone
E) vitamin D

Accepted Answer

Parathyroid hormone (PTH) analogs, like teriparatide, are used in the treatment of osteoporosis as they stimulate bone formation and increase bone density. Although the primary function of PTH is to respond to reduced circulating Ca₂₊ levels and a portion of its action results in resorption of bone Ca₂₊, the use of recombinant PTH has proven beneficial in the treatment of osteoporosis. PTH increases bone turnover (resorption) but it also increases the formation of new bone and the latter effect on bone is more pronounced than resorption. Intermittent infusion of recombinant PTH results in new bone formation and has shown efficacy in the treatment of the bone loss associated with osteoporosis

Question 3

You are treating a 27-year-old male patient for recent onset of hypertension. The patient reports that he has not consumed any alcohol nor does he use any medications or illegal drugs. Analysis of serum electrolytes indicates a reduced level of potassium. You suspect the patient is experiencing a disruption in the normal responses to vascular volume. A blood test to assay for an increase in which of the following hormones would be useful in the diagnosis of the cause of the hypertension in this patient?
A) atrial natriuretic peptide
B) oxytocin
C) parathyroid hormone
D) renin
E) thyroid-stimulating hormone

Accepted Answer

An increase in renin can lead to hypertension and hypokalemia due to hyperaldosteronism, which causes increased sodium retention and potassium excretion.  The renin-angiotensin system is responsible for regulation of blood pressure. The intrarenal baroreceptor system is a key mechanism for regulating renin secretion. A drop in pressure results in the release of renin from the juxtaglomerular cells of the kidneys. Renin cleaves a 10-amino-acid peptide from the N-terminal end of angiotensinogen-generating angiotensin I. Angiotensin I is then cleaved by the action of angiotensin-converting enzyme (ACE) generating the bioactive hormone, angiotensin II. Increased production of renin would, therefore, lead to inappropriate generation of angiotensin II and an associated hypertension.

Question 4

You are an experimental endocrinologist studying the effects of a peptide analog on the functions of the kidney. When you administer the analog to laboratory mice you are able to measure a significant increase in urinary excretion of sodium. Which of the following known peptides exerts effects most similar to your peptide analog?
A) atrial natriuretic peptide
B) calcitonin
C) irisin
D) oxytocin
E) renin

Accepted Answer

Atrial natriuretic peptide (ANP) is known to increase the excretion of sodium in the urine, a process known as natriuresis, which aligns with the effects observed with the peptide analog in the study.  Natriuresis refers to enhanced urinary excretion of sodium. Atrial natriuretic peptide (ANP) was the first cardiac natriuretic hormone identified. This hormone is secreted by cardiac muscle when sodium chloride intake is increased and when the volume of the extracellular fluid expands. Although the precise mode of action of ANP to increase sodium excretion has not been characterized, it is known that ANP induces relaxation of the mesangial cells of the glomeruli and thus may increase the surface area of these cells so that filtration is increased. Alternatively, ANP might act on tubule cells to increase sodium excretion.

Question 5

You are treating a 63-year-old postmenopausal woman who has complained that she no longer has the ability to stand erect without pain. She also reports that she suffered a minor ulna fracture when she accidently bumped into the door frame entering her bathroom. An x-ray of her spine demonstrates vertebral thinning typical of osteoporosis. In the absence of recombinant parathyroid therapy, which of the following hormones would be most useful in treating this woman's condition?
A) ACTH
B) calcitonin
C) corticotropin-releasing hormone
D) growth hormone
E) thyroid stimulating hormone

Accepted Answer

Calcitonin is a hormone that helps regulate calcium levels in the body and can be used to treat osteoporosis by inhibiting bone resorption.  Calcitonin is a hypocalcemic peptide that exerts its effects in numerous species by antagonizing the effects of PTH. In humans, however, the role of calcitonin in calcium homeostasis is of limited physiological significance. In humans, the major benefits of calcitonin are its use in the treatment of osteoporosis and to suppress bone resorption in Paget disease.

Question 6

A hormone of the hypothalamic-pituitarygonadal axis is known to stimulate follicular development and estrogen synthesis by granulosa cells of the ovary of female. In males, this same hormone promotes testicular growth and it enhances the synthesis and secretion of testosterone and dihydrotestosterone by Sertoli cells. Which of the following is the hormone exerting these actions?
A) follicle-stimulating hormone
B) gonadotropin-releasing hormone
C) growth hormone
D) luteinizing hormone
E) prolactin-releasing hormone

Accepted Answer

Follicle-stimulating hormone (FSH) stimulates follicular development and estrogen synthesis in females and promotes testicular growth and supports spermatogenesis in males. In females, FSH stimulates follicular development and estrogen synthesis by granulosa cells of the ovary. In males, FSH promotes testicular growth and within the Sertoli cells of the testes it enhances the synthesis and secretion of T and DHT.

Question 7

You are treating a 37-year-old woman who complains of an extreme thirst. She gets the greatest relief from consuming large quantities of ice water or by sucking on ice cubes. She reports that she also has to frequently urinate. You suspect she may be suffering from diabetes mellitus but assay for urine glucose shows that it is not elevated. Indeed the patient's urine is quite dilute. A deficiency in which of the following hormones is the most likely cause of the symptoms in this woman?
A) ACTH
B) follicle-stimulating hormone
C) renin
D) thyroid-stimulating hormone
E) vasopressin

Accepted Answer

The symptoms of extreme thirst and frequent urination with dilute urine suggest diabetes insipidus, which is caused by a deficiency in vasopressin (antidiuretic hormone, ADH). The secretion of vasopressin is regulated in the hypothalamus by osmoreceptors, which sense water and Na+ concentration and stimulate increased vasopressin secretion when plasma osmolarity increases. The secreted vasopressin increases the reabsorption rate of water in kidney tubule cells, causing the excretion of urine that is concentrated in Na⁺ and thus yielding a net drop in osmolarity of body fluids. Vasopressin deficiency leads to production of large volumes of watery urine and to polydipsia. These symptoms are diagnostic of diabetes insipidus.

Question 8

As the level of visceral fat increases, there is a concomitant loss of peripheral tissue responses to insulin. Adipose tissue responses to these metabolic changes include a reduced secretion of which of the following adipokines?
A) adiponectin
B) adipsin
C) IL-6
D) leptin
E) resistin

Accepted Answer

Adiponectin is an adipokine that enhances insulin sensitivity. As visceral fat increases, adiponectin secretion decreases, contributing to insulin resistance.  Expression and release of adiponectin is stimulated by insulin and inhibited by TNF-α. Levels of adiponectin are reduced in obese individuals and increased in patients with anorexia nervosa. There are sex-related differences in adiponectin levels as well similar to that seen for leptin where age and weight matched males have lower levels than females. In patients with type 2 diabetes, levels of adiponectin are significantly reduced.

Question 9

Blocking the actions of which of the following hormones would be expected to lead to the greatest level of appetite suppression?
A) adiponectin
B) ghrelin
C) GLP-1
D) obestatin
E) peptide tyrosine tyrosine, PYY

Accepted Answer

Ghrelin is known as the "hunger hormone" because it stimulates appetite. Blocking ghrelin would likely lead to significant appetite suppression.  Ghrelin is produced and secreted by the X/A-like enteroendocrine cells of the stomach oxyntic (acid secreting) glands. The major effect of ghrelin is exerted within the central nervous system at the level of the arcuate nucleus where it stimulates the release of neuropeptide Y (NPY) and agouti-related protein (AgRP). The actions of NPY and AgRP enhance appetite and, thus, food intake.

Question 10

You are treating a patient exhibiting hypotension who also manifests with signs of hepatic failure. The hypotension associated with liver failure most closely reflects an imbalance in which of the following hormone systems?
A) ACTH
B) aldosterone
C) corticotropin-releasing hormone (CRH)
D) cortisol
E) renin-angiotensin

Accepted Answer

The hypotension in liver failure is often due to splanchnic vasodilation and a decrease in systemic vascular resistance, which is closely related to an imbalance in the renin-angiotensin system.  The renin-angiotensin system is responsible for regulation of blood pressure. The intrarenal baroreceptor system is a key mechanism for regulating renin secretion. A drop in pressure results in the release of renin from the juxtaglomerular cells of the kidneys. The only function for renin is to cleave a 10-amino-acid peptide from the N-terminal end of angiotensinogengenerating angiotensin I. Angiotensin I is then cleaved by angiotensin converting enzyme yielding angiotensin II. Angiotensinogen is produced by and secreted from hepatocytes. In individuals that are depleted of sodium or who have liver disease (eg, cirrhosis), the pressive actions of angiotensin II are greatly reduced

Question 11

Interference with the action of angiotensinconverting enzyme (ACE) is an effective means at reducing elevations in blood pressure. The circulating concentration of which of the following hormones would be affected as a consequence of the use of ACE inhibitors?
A) ACTH
B) aldosterone
C) corticotrophin-releasing hormone, CRH
D) estradiol
E) gonadotropin-releasing hormone, GnRH

Accepted Answer

ACE inhibitors reduce the production of angiotensin II, which in turn decreases the secretion of aldosterone from the adrenal glands. Angiotensin-converting enzyme (ACE) is responsible for the cleavage of 2 amino acids from angiotensin I, generating angiotensin II. Angiotensin II is a peptide hormone of the rennin-angiotensin system responsible for regulation of blood pressure. The intra-renal baroreceptor system is a key mechanism for regulating renin secretion. A drop in pressure results in the release of renin from the juxtaglomerular cells of the kidneys. Renin secretion is also regulated by the rate of Na⁺ and Cl⁻ transport across the macula densa. The higher the rate of transport of these ions, the lower is the rate of renin secretion. The only function for renin is to cleave a 10-amino-acid peptide from the N-terminal end of angiotensinogen yielding angiotensin I. ACE action then generates angiotensin II, one of the most potent naturally occurring vasoconstrictors. In addition to the vascular effects, other physiological responses to angiotensin II include induction of adrenal cortex synthesis and secretion of aldosterone. Release of aldosterone leads to further Na+ retention by the kidneys with the consequences being an additional pressive effect on the vasculature. Thus, the use of ACE inhibitors would not only reduce the production of angiotensin II but also aldosterone.

Question 12

Which of the following is the hypophyseotropic hormone that regulates the activity of the lactotrophs of the anterior pituitary?
A) corticotrophin-releasing hormone, CRH
B) gonadotropin-releasing hormone, GnRH
C) growth hormone-releasing hormone, GRH
D) prolactin-releasing factor, PRF
E) thyrotropin-releasing hormone, TRH

Accepted Answer

Prolactin-releasing factor (PRF) is the hypophyseotropic hormone that regulates the activity of lactotrophs, which are responsible for producing prolactin in the anterior pituitary.  The lactotrophs of the anterior pituitary secrete prolactin in response to the action of prolactin releasing factor, PRF.

Question 13

In renal insufficiency, calcium absorption is reduced and leads to increased bone resorption, a condition referred to as renal osteodystrophy. Treatment with which of the following can assist in the amelioration of the symptoms of this condition?
A) antidiuretic hormone
B) calcitonin
C) calcitriol
D) growth hormone
E) parathyroid hormone

Accepted Answer

Calcitriol, the active form of vitamin D, helps increase calcium absorption from the gut, which can help counteract the effects of renal osteodystrophy by reducing bone resorption. Calcitriol [1,25-(OH)₂-D] is the hormonally active form of vitamin D and functions in concert with PTH and calcitonin to regulate serum calcium and phosphorous levels. The major function of calcitriol is the induction of synthesis of an intestinal calcium-binding protein, calbinden, which facilitates intestinal absorption of calcium. Oral administration of calcitriol will increase intestinal calcium uptake, but the hormone does not enter the peripheral circulation in significant amounts. Therefore, patients with renal osteodystrophy may need intravenous administration of calcitriol.

Question 14

A 17-year-old adolescent boy who reports to his physician that he is incapable of obtaining an erection is also quite embarrassed by the apparent enlargement of his breasts (gynecomastia). These symptoms, when present in males, are associated with an excessive production of which of the following hormones?
A) corticotropin-releasing hormone
B) gonadotropin-releasing hormone
C) growth hormone
D) melanocyte-stimulating hormone
E) prolactin

Accepted Answer

Excessive production of prolactin in males can lead to symptoms such as erectile dysfunction and gynecomastia due to its effects on reducing testosterone levels and increasing estrogen levels.  Prolactin is necessary for initiation and maintenance of lactation. Physiologic levels act only on breast tissue primed by female sex hormones. Endocrine dysfunction leading to excessive prolactin production is associated with breast enlargement and impotence in males.

Question 15

Acromegaly is characterized by protruding jaw; enlargement of the nose, hands, feet, and skull; and a thickening of the skin. This disorder is the result of excessive production of which of the following hormones?
A) corticotropin-releasing hormone
B) gonadotropin-releasing hormone
C) growth hormone
D) insulin-like growth factor II
E) thyroid-stimulating hormone

Accepted Answer

Acromegaly is caused by excessive production of growth hormone, usually due to a pituitary adenoma.  Acromegaly results when there is an excess production of growth hormone after epiphysial closure and cessation of long bone growth.

Question 16

A patient is diagnosed with problems in emptying the gallbladder. On a blood checkup, one hormone/ peptide that is known to stimulate gallbladder contraction is inappropriately low. Which of the following hormones is most likely deficient leading to the observed symptoms?
A) cholecystokinin
B) gastrin
C) GLP-1
D) pancreatic polypeptide
E) peptide tyrosine tyrosine (PYY)

Accepted Answer

Cholecystokinin (CCK) is the hormone responsible for stimulating gallbladder contraction and bile release. A deficiency in CCK would lead to problems in emptying the gallbladder.  Cholecystokinin (CCK) is secreted from enteroendocrine I cells, predominantly of the duodenum, jejunum, following the consumption of food. The primary digestive effects of CCK are to stimulate gallbladder contraction and bile flow and increase secretion of digestive enzymes from the pancreas.

Question 17

The pancreas play an important role in the control of blood glucose by its secretion of insulin and glucagon. The release of insulin and glucagon is inhibited by somatostatin, which is also secreted by the pancreas. Which of the following cells of the pancreas secrete somatostatin?
A) acinar cells
B) α-cells
C) β-cells
D) δ-cells
E) F cells

Accepted Answer

δ-cells (delta cells) of the pancreas secrete somatostatin, which inhibits the release of insulin and glucagon. Delta cells of the islet of Langerhans in the pancreas secrete somatostatin-14, a 14-aminoacid peptide, that inhibits the release of insulin and glucagon

Question 18

A well-nourished 21-year-old woman presents with hypocalcemia. Her blood concentration of parathyroid hormone (PTH) is 150 pg/mL (normal 10-65 pg/mL). Her blood concentration of 1,25-dihydroxycholecalciferol is normal. Her BUN is normal. She is treated with a synthetic version of human PTH, and her blood calcium concentration normalizes. Which of the following is most likely causing her hypocalcemia?
A) decrease in total number of PTH receptors in kidney
B) deficiency of 1-α-hydroxylase activity in kidney
C) hepatocellular defect
D) secretion of an inactive PTH hormone molecule
E) severe vitamin D deficiency

Accepted Answer

The elevated PTH levels with normal 1,25-dihydroxycholecalciferol and normalization of calcium with synthetic PTH suggest that the endogenous PTH is inactive, likely due to a secretion of an inactive PTH hormone molecule. PTH promotes calcium reabsorption from distal tubules of the nephron. A high PTH value is the body's normal response to a low level of calcium in the blood. The facts that the woman responds normally to synthetic human PTH and that her BUN is normal exclude kidney failure as a cause of her hypocalcemia and make the release of an inactive PTH the best choice.

Question 19

Which of the following refers to peptide hormones whose actions are exerted on cells adjacent to their site of synthesis but not on the cell of synthesis?
A) autocrine
B) chemokine
C) exocrine
D) paracrine

Accepted Answer

Paracrine signaling involves hormones acting on nearby cells, not on the cell that synthesized them.  Hormones that are synthesized in one cell and released into the surroundings to act on adjacent cells are referred to as paracrine hormones.

Question 20

A motor vehicle accident caused complete pituitary stalk transection. Secretion of all pituitary hormones is lost except for one, whose blood level actually increases. Which one of the following pituitary hormones is distinctive in that its primary control is by inhibition rather than stimulation by the hypothalamus?
A) gonadotropin-releasing hormone
B) growth hormone
C) prolactin
D) proopiomelanocortin, POMC
E) thyroid-stimulating hormone

Accepted Answer

Prolactin is primarily controlled by inhibition from the hypothalamus via dopamine. When the pituitary stalk is transected, the inhibitory control is lost, leading to an increase in prolactin levels. The primary control over prolactin secretion is inhibition by hypothalamic dopamine; all other anterior pituitary hormones are primarily controlled by hypothalamic hormone stimulation. Hence, with stalk transection, loss of connection of the hypothalamus to the pituitary is associated with decreased secretion of all pituitary hormones except prolactin, whose secretion increases in the absence of dopamine.

Quiz 49: Peptide Hormones

As the level of visceral fat increases, there is a concomitant loss of peripheral tissue responses to insulin. Adipose tissue responses to these metabolic changes include a reduced secretion of which of the following adipokines?

Blocking the actions of which of the following hormones would be expected to lead to the greatest level of appetite suppression?

You are treating a patient exhibiting hypotension who also manifests with signs of hepatic failure. The hypotension associated with liver failure most closely reflects an imbalance in which of the following hormone systems?

Interference with the action of angiotensinconverting enzyme (ACE) is an effective means at reducing elevations in blood pressure. The circulating concentration of which of the following hormones would be affected as a consequence of the use of ACE inhibitors?

Which of the following is the hypophyseotropic hormone that regulates the activity of the lactotrophs of the anterior pituitary?

In renal insufficiency, calcium absorption is reduced and leads to increased bone resorption, a condition referred to as renal osteodystrophy. Treatment with which of the following can assist in the amelioration of the symptoms of this condition?

Acromegaly is characterized by protruding jaw; enlargement of the nose, hands, feet, and skull; and a thickening of the skin. This disorder is the result of excessive production of which of the following hormones?

A patient is diagnosed with problems in emptying the gallbladder. On a blood checkup, one hormone/ peptide that is known to stimulate gallbladder contraction is inappropriately low. Which of the following hormones is most likely deficient leading to the observed symptoms?

The pancreas play an important role in the control of blood glucose by its secretion of insulin and glucagon. The release of insulin and glucagon is inhibited by somatostatin, which is also secreted by the pancreas. Which of the following cells of the pancreas secrete somatostatin?

Which of the following refers to peptide hormones whose actions are exerted on cells adjacent to their site of synthesis but not on the cell of synthesis?