Block 5 Parthyroid Phys Pharm MCQ's

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Questions and Answers
  • 1. 

    A 34 year-old female patient is seen for kidney stones. The physician orders blood work and asks the patient to collect her urine over a 24 hour period. The results of the laboratory tests show a modest increase in plasma [Ca++] and substantial decrease in the Ca++ in her urine. An increase in what hormone would most likely account for these findings?

    • A. 

      Calcitriol

    • B. 

      Calcitonin

    • C. 

      Estrogen

    • D. 

      Parathyroid hormone

    • E. 

      Leptin

    Correct Answer
    D. Parathyroid hormone
    Explanation
    Parathyroid hormone is the most likely hormone to account for the findings of a modest increase in plasma calcium and a substantial decrease in urine calcium. Parathyroid hormone is responsible for regulating calcium levels in the body. It acts on the bones, kidneys, and intestines to increase calcium levels in the blood. In this case, the increase in plasma calcium suggests that parathyroid hormone is stimulating the release of calcium from the bones. The decrease in urine calcium indicates that the kidneys are reabsorbing more calcium, which is also regulated by parathyroid hormone.

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  • 2. 

    Hyperparathyroidism usually decreases the plasma level of which ion?

    • A. 

      Iron

    • B. 

      Calcium

    • C. 

      Phosphate

    • D. 

      Potassium

    • E. 

      Sodium

    Correct Answer
    C. Phosphate
    Explanation
    Hyperparathyroidism is a condition where the parathyroid glands produce too much parathyroid hormone (PTH), which regulates the levels of calcium and phosphate in the body. In this condition, the increased PTH levels cause the kidneys to excrete more phosphate, leading to a decrease in the plasma level of phosphate. Therefore, the correct answer is phosphate.

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  • 3. 

    In children, how do parathyroid hormone (PTH) and calcitonin affect bone deposition and resorption?

    • A. 

      PTH increases bone deposition and calcitonin increases bone resorption

    • B. 

      PTH increases bone resorption and calcitonin inhibits bone resorption

    • C. 

      PTH increases bone resorption and calcitonin increases bone resorption

    • D. 

      PTH increases bone deposition and calcitonin inhibits bone resorption

    • E. 

      PTH increases bone deposition and calcitonin has no influence on either bone deposition or resorption

    Correct Answer
    B. PTH increases bone resorption and calcitonin inhibits bone resorption
    Explanation
    PTH, or parathyroid hormone, stimulates bone resorption, which is the process of breaking down bone tissue. This increases the release of calcium from the bone into the bloodstream. On the other hand, calcitonin inhibits bone resorption, preventing the breakdown of bone tissue and reducing the release of calcium into the bloodstream. Therefore, PTH increases bone resorption, while calcitonin inhibits bone resorption.

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  • 4. 

    A 54-year-old woman takes dietary supplements that provide her with 1000 mg of elemental calcium per day. If she had already been on a normal diet, what effect will this supplement have on hormone levels in her plasma?"

    • A. 

      A decrease in circulating PTH (parathyroid hormone) levels.

    • B. 

      A decrease in circulating CT (calcitonin) levels

    • C. 

      A decrease in vitamin D levels.

    • D. 

      A decrease in 25(OH)D levels.

    • E. 

      A decrease in 1,25(OH)2D levels.

    • F. 

      A decrease in thyroid hormone levels.

    • G. 

      No effect

    Correct Answer
    G. No effect
    Explanation
    The dietary supplements providing 1000 mg of elemental calcium per day will not have any effect on hormone levels in the woman's plasma. Calcium supplementation does not directly affect hormone levels such as PTH, CT, vitamin D, or thyroid hormones. Therefore, there will be no change in hormone levels due to the calcium supplements.

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  • 5. 

    Which of the following drugs stimulate new bone formation?

    • A. 

      Calcitriol

    • B. 

      Alendronate

    • C. 

      Estradiol

    • D. 

      Raloxifene

    • E. 

      Teriparatide

    • F. 

      Cinacalcet

    Correct Answer
    E. Teriparatide
    Explanation
    Teriparatide is a drug that stimulates new bone formation. It is used in the treatment of osteoporosis by promoting the production of new bone cells. Teriparatide is a synthetic form of parathyroid hormone, which helps to increase bone density and reduce the risk of fractures. It works by stimulating the activity of osteoblasts, the cells responsible for bone formation. This drug is particularly effective in individuals with severe osteoporosis or those who have not responded well to other treatments.

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  • 6. 

    A 64-year-old man complains to his physician of lower back pain. He reports that he has had rheumatoid arthritis for over 10 years, for which he takes oral prednisone, but the new back pain is different. Physical exam reveals nothing remarkable, except that he is an inch shorter than at his last visit, 1.5 years ago. Which of the following actions of prednisone are most likely to be contributing to the new back pain?

    • A. 

      Inhibition of intestinal calcium absorption

    • B. 

      Decreased ACTH secretion

    • C. 

      Increased blood glucose levels

    • D. 

      Decreased IL-1, IL-2 and 11-6 actions

    • E. 

      Body fat redistribution

    Correct Answer
    A. Inhibition of intestinal calcium absorption
    Explanation
    Prednisone is a glucocorticoid medication that can cause osteoporosis and bone loss. Inhibition of intestinal calcium absorption is a known side effect of prednisone, which can lead to decreased bone density and increased risk of fractures. This can result in lower back pain, especially in individuals with pre-existing conditions such as rheumatoid arthritis.

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  • 7. 

    Which of the following is an expected metabolic response to HIGH plasma calcium levels?

    • A. 

      Increased parathyroid hormone release

    • B. 

      Decreased synthesis of 1,25 dihydroxy vitamin D3

    • C. 

      Increased calcium absorption from the intestine

    • D. 

      Decreased renal excretion of calcium

    • E. 

      Increased calcium mobilization from bone

    Correct Answer
    B. Decreased synthesis of 1,25 dihydroxy vitamin D3
    Explanation
    When plasma calcium levels are high, the body's response is to decrease the synthesis of 1,25 dihydroxy vitamin D3. This is because 1,25 dihydroxy vitamin D3 helps increase the absorption of calcium from the intestine, and when plasma calcium levels are already high, there is no need for further absorption. By decreasing the synthesis of 1,25 dihydroxy vitamin D3, the body can help regulate calcium levels and prevent them from becoming too elevated.

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  • 8. 

    A 19 YO man decides to begin a vegan diet , but he fails to adequately compensate for the nutritional content of the dairy products in his former diet, so his intake of calcium drops dramatically. Which of the following hormones' direct actions will be most important in the maintenance of his plasma calcium?

    • A. 

      Insulin

    • B. 

      Thyroid hormone

    • C. 

      Calcitonin

    • D. 

      1,25-dihydroxycholecalciferol

    • E. 

      Parathyroid hormone

    Correct Answer
    D. 1,25-dihydroxycholecalciferol
    Explanation
    1,25-dihydroxycholecalciferol, also known as active vitamin D, is the most important hormone in maintaining plasma calcium levels. When calcium levels drop, the parathyroid glands release parathyroid hormone (PTH), which stimulates the production of 1,25-dihydroxycholecalciferol in the kidneys. 1,25-dihydroxycholecalciferol then acts on the intestines, kidneys, and bones to increase calcium absorption from the diet, reabsorption from the kidneys, and release from the bones. This helps to restore and maintain normal plasma calcium levels.

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  • 9. 

    Adrenal Gland Physiology, Pharmacology and Biochemistry: A predominantly male patient mentions that his childhood sexual development was a bit turbulent because of 5a-reductase deficiency. What is the function of 5a-reductase?

    • A. 

      A) Makes testosterone in the testis

    • B. 

      B) Is needed for the synthesis of glucocorticoids and mineralocorticoids

    • C. 

      C) Turns testosterone into highly potent dihydrotestosterone

    • D. 

      D) Turns androgens into estrogens

    • E. 

      E) Catalyzes the conversion of cholesterol into pregnenolone

    Correct Answer
    C. C) Turns testosterone into highly potent dihydrotestosterone
    Explanation
    5a-reductase is an enzyme that converts testosterone into dihydrotestosterone (DHT), which is a more potent androgen. This conversion is important for the normal development of male sexual characteristics during puberty. In the case of 5a-reductase deficiency, the patient may experience abnormal sexual development due to the reduced production of DHT.

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  • 10. 

    A 48 YO man with a family history of heart disease has followed a heart-healthy lifestyle for 15 years. However, he has recently experienced unusual fatigue and lightheadedness, especially when rising suddenly. Physical examination demonstrates postural hypotension and a darker-than usual complexion for midwinter in the Midwest (he works and exercises indoors). Lab work reveals that he is hyponatremic, hyperkalemic, and hypocalcemic. Further blood tests are ordered to assay plasma corticotropin-releasing hormone (CRH), corticotropin (ACTH), and cortisol. What combination of hyper and/or hyposecretion for these hormones would be the most likely given this man's signs and symptoms?   CRH secretion ACTH secretion Cortisol secretion         A hypersecretion hypersecretion hypersecretion B hypersecretion hypersecretion hyposecretion C hypersecretion hyposecretion hyposecretion D hyposecretion hyposecretion hyposecretion E hyposecretion hyposecretion hypersecretion

    • A. 

      A

    • B. 

      B

    • C. 

      C

    • D. 

      D

    • E. 

      E

    Correct Answer
    B. B
    Explanation
    The most likely combination of hyper and/or hyposecretion for these hormones would be hypersecretion of CRH and ACTH, and hyposecretion of cortisol. This is because the patient is experiencing symptoms of adrenal insufficiency, such as fatigue and lightheadedness, which can be caused by a deficiency in cortisol production. The darker-than-usual complexion and hyponatremia are also consistent with adrenal insufficiency. The hypersecretion of CRH and ACTH can be a compensatory mechanism due to the low levels of cortisol.

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  • 11. 

    A patient with lethargy, nausea, and reported muscle weakness is given a series of tests to rule out physical causes. During these tests it is revealed that plasma corticotropin is above normal and cortisol is below normal. Renin is above normal and aldosterone is below normal. Adrenal androgens are below normal. Which of the following clinical conditions would be most likely to produce this set of signs and symptoms?

    • A. 

      Cushing's Disease

    • B. 

      Ectopic corticotropin-producing tumor

    • C. 

      Secondary renal insufficiency

    • D. 

      Congenital adrenal hyperplasia E) Addison's Disease

    • E. 

      Addison's Disease

    Correct Answer
    E. Addison's Disease
    Explanation
    The patient's symptoms of lethargy, nausea, and muscle weakness, along with the abnormal levels of plasma corticotropin, cortisol, renin, aldosterone, and adrenal androgens, are consistent with Addison's Disease. This condition is characterized by the adrenal glands not producing enough cortisol and aldosterone. The elevated levels of plasma corticotropin suggest a primary defect in the adrenal glands, ruling out secondary renal insufficiency. Cushing's Disease and ectopic corticotropin-producing tumors would result in elevated cortisol levels, which is not seen in this patient. Congenital adrenal hyperplasia would typically present with elevated levels of adrenal androgens, which is not the case here.

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  • 12. 

    Within the chromaffin cells of the adrenal medulla, which ion's influx is an absolute requirement for epinephrine secretion?

    • A. 

      Calcium

    • B. 

      Sodium

    • C. 

      Chloride

    • D. 

      Potassium

    • E. 

      Iodide

    Correct Answer
    A. Calcium
    Explanation
    Calcium's influx is an absolute requirement for epinephrine secretion in the chromaffin cells of the adrenal medulla. This is because calcium plays a crucial role in the process of exocytosis, which is the release of secretory vesicles containing epinephrine into the bloodstream. When calcium enters the chromaffin cells, it triggers the fusion of these vesicles with the cell membrane, allowing the release of epinephrine. Without calcium influx, the secretion of epinephrine cannot occur.

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  • 13. 

    What would be an expected outcome of 11-deoxycorticosterone-induced hypervolemia and hypertension on the renin-angiotensin-aldosterone system?   [renin]pi [angiotensin II]pi [aldosterone]pi A Increase Increase Increase B Decrease Decrease Decrease C Increase Decrease Decrease D Decrease Increase Decrease E Decrease Decrease Increase

    • A. 

      A

    • B. 

      B

    • C. 

      C

    • D. 

      D

    • E. 

      E

    Correct Answer
    B. B
    Explanation
    The expected outcome of 11-deoxycorticosterone-induced hypervolemia and hypertension on the renin-angiotensin-aldosterone system would be a decrease in renin, angiotensin II, and aldosterone levels. This is because 11-deoxycorticosterone is a mineralocorticoid hormone that acts similarly to aldosterone, causing sodium and water retention. This increased blood volume and pressure would lead to a negative feedback loop, suppressing the release of renin from the kidneys and subsequently decreasing the production of angiotensin II and aldosterone.

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  • 14. 

    Polyuria, polydipsia, weakness, and fatigue are characteristic of several endocrine disorders. In one patient, the physician notes both peripheral neuropathy and visual changes as well. What clinical condition would be most likely to produce these six findings?

    • A. 

      Addison's disease

    • B. 

      Conn's syndrome

    • C. 

      Cushing's syndrome

    • D. 

      Diabetes mellitus

    • E. 

      Diabetes insipidus

    Correct Answer
    D. Diabetes mellitus
    Explanation
    Diabetes mellitus is the most likely clinical condition to produce these six findings. Polyuria and polydipsia are common symptoms of diabetes mellitus, as the high levels of glucose in the blood cause increased urine production and excessive thirst. Weakness and fatigue can also be attributed to the body's inability to properly use glucose for energy. The presence of peripheral neuropathy and visual changes further support the diagnosis of diabetes mellitus, as these are common complications associated with the disease.

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  • 15. 

    What branch of the autonomic nervous system elicits catecholamine release from the adrenal medulla and what is the neurotransmitter and receptor responsible for increased epinephrine release from adrenal medullary chromaffin cells?   Branch of ANS Neurotransmitter Receptor A Parasympathetic Norepinephrine Alpha-1 B Sympathetic Norepinephrine Alpha-1 C Sympathetic Acetylcholine Muscarinic D Parasympathetic Acetylcholine Muscarinic E Sympathetic Acetylcholine Nicotinic  

    • A. 

      A

    • B. 

      B

    • C. 

      C

    • D. 

      D

    • E. 

      E

    Correct Answer
    E. E
    Explanation
    The correct answer is E. The sympathetic branch of the autonomic nervous system elicits catecholamine release from the adrenal medulla. The neurotransmitter responsible for increased epinephrine release from adrenal medullary chromaffin cells is acetylcholine, and the receptor involved is nicotinic.

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  • 16. 

    A 43-year old female patient comes to your office with the following symptoms: lethargy, postural hypotension, recent weight loss, and muscle weakness. Your tentative diagnosis is adrenal cortical dysfunction. You order a set of laboratory tests which come back with the following results: undetectable levels of plasma ACTH and very low plasma cortisol. In addition, you can demonstrate that exogenous CRF increases plasma cortisol. What is the most likely explanation for this patient's endocrine problem?

    • A. 

      Disappearance of cortisol producing adrenal cortical cells

    • B. 

      Nonfunctional corticotrophs of the anterior pituitary

    • C. 

      Nonfunctional corticotrophs of the posterior pituitary

    • D. 

      Insufficient production of CRF by hypothalamic neurons.

    • E. 

      Absence of ACTH receptors on adrenal cortical cells.

    Correct Answer
    D. Insufficient production of CRF by hypothalamic neurons.
    Explanation
    The most likely explanation for this patient's endocrine problem is insufficient production of CRF by hypothalamic neurons. This is supported by the undetectable levels of plasma ACTH and very low plasma cortisol. CRF is responsible for stimulating the release of ACTH, which in turn stimulates the production and release of cortisol by the adrenal cortex. Therefore, if there is insufficient production of CRF, it would result in low levels of ACTH and cortisol. The fact that exogenous CRF increases plasma cortisol further supports this explanation, as it suggests that the patient's adrenal cortex is still capable of producing cortisol when stimulated.

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  • 17. 

    In pheochromocytoma, 3-methoxy-4-hydroxymandelic acid is formed enzymatically as a breakdown product of norepinephrine. The formation of this metabolite would be slowed down not only by inhibitors of MAO or COMT, but also by a

    • A. 

      Glutamate decarboxylase inhibitor

    • B. 

      COX-2 inhibitor

    • C. 

      Tricyclic antidepressant

    • D. 

      Tryptophan hydroxylase inhibitor

    • E. 

      Tyrosine hydroxylase inhibitor

    Correct Answer
    C. Tricyclic antidepressant
    Explanation
    Tricyclic antidepressants are known to inhibit the reuptake of norepinephrine, increasing its availability in the synaptic cleft. This increased concentration of norepinephrine would lead to an increased breakdown of norepinephrine, resulting in higher levels of 3-methoxy-4-hydroxymandelic acid. Thus, the presence of a tricyclic antidepressant would slow down the formation of this metabolite in pheochromocytoma.

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  • 18. 

    Of these drugs, the one best suited for the treatment of pheochromocytoma is a

    • A. 

      Glutamate decarboxylase inhibitor

    • B. 

      COX-2 inhibitor

    • C. 

      Tricyclic antidepressant

    • D. 

      Tryptophan hydroxylase inhibitor

    • E. 

      Tyrosine hydroxylase inhibitor

    Correct Answer
    E. Tyrosine hydroxylase inhibitor
    Explanation
    A pheochromocytoma is a tumor of the adrenal gland that causes excessive production of catecholamines, such as epinephrine and norepinephrine. These catecholamines are synthesized from the amino acid tyrosine by the enzyme tyrosine hydroxylase. By inhibiting tyrosine hydroxylase, the production of catecholamines can be reduced, which can help in the treatment of pheochromocytoma. Therefore, a tyrosine hydroxylase inhibitor would be the best-suited drug for this condition.

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  • 19. 

    Which of the following aspects of hormone storage, transport, or action are common to both thyroid hormone and steroid hormones?

    • A. 

      Activate receptor tyrosine kinase.

    • B. 

      Are stored in granules

    • C. 

      Travel primarily as free hormones in the circulation.

    • D. 

      Are highly bound to plasma proteins.

    • E. 

      Have half-lives of about 1 minute.

    Correct Answer
    D. Are highly bound to plasma proteins.
    Explanation
    Both thyroid hormone and steroid hormones are highly bound to plasma proteins. This means that only a small fraction of the hormones are free and available for action. The majority of the hormones are bound to proteins such as albumin, which serves as a reservoir for the hormones and helps to regulate their availability and distribution in the body. This binding also affects the half-life of the hormones, as it slows down their metabolism and clearance from the circulation. Therefore, the high binding to plasma proteins is a common aspect of both thyroid hormone and steroid hormone storage, transport, and action.

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  • 20. 

    In the synthesis of adrenal medullary hormones cortisol stimulates the conversion of

    • A. 

      Tyrosine to dopa.

    • B. 

      Tyrosine to dopamine.

    • C. 

      Dopamine to dopa.

    • D. 

      Epinephrine to norepinephrine.

    • E. 

      Norepinephrin to epinephrine.

    Correct Answer
    D. Epinephrine to norepinephrine.
    Explanation
    Cortisol stimulates the conversion of epinephrine to norepinephrine in the synthesis of adrenal medullary hormones.

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  • 21. 

    Select the cardiovascular effect that will most likely result from activation of beta-1 and beta-2 receptors by the catecholamines released from the adrenal medulla.

    • A. 

      Increased CO, increased TPR, decreased HR

    • B. 

      Increased CO, decreased TPR, increased HR

    • C. 

      Decreased CO, decreased TPR, increased HR.

    • D. 

      Decreased CO, decreased TPR, decreased HR

    • E. 

      Decreased CO, decreased TPR, decreased HR

    Correct Answer
    B. Increased CO, decreased TPR, increased HR
    Explanation
    Activation of beta-1 and beta-2 receptors by catecholamines released from the adrenal medulla will result in increased cardiac output (CO) due to increased contractility and heart rate (HR) mediated by beta-1 receptors. This is accompanied by decreased total peripheral resistance (TPR) due to vasodilation mediated by beta-2 receptors. Therefore, the correct answer is Increased CO, decreased TPR, increased HR.

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  • 22. 

    In situations of stress and anxiety, epinephrine synthesis can be increased when cortisol Stimulates the enzyme

    • A. 

      Tyrosine hydroxylase

    • B. 

      Amino acid decarboxylase

    • C. 

      COMT( catecholamine-O- methyl-transferase)

    • D. 

      MAO(monoamine oxidase)

    • E. 

      PNMT(phenylethanolamine-N-methyl transferase)

    Correct Answer
    E. PNMT(phenylethanolamine-N-methyl transferase)
    Explanation
    PNMT (phenylethanolamine-N-methyl transferase) is the correct answer because it is the enzyme responsible for the synthesis of epinephrine from norepinephrine. In situations of stress and anxiety, cortisol stimulates the production of norepinephrine, and then PNMT converts norepinephrine into epinephrine. This increase in epinephrine synthesis helps the body respond to stress by increasing heart rate, blood pressure, and energy availability.

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