Endocrine Pharmacology Practice Questions

Q: Precocious puberty is treated by administering

LHRH analogs (e.g., Leuprolide). ***LHRH analogs (e.g., Leuprolide)*** - **LHRH analogs** (GnRH agonists) are the standard treatment for central precocious puberty through continuous, non-pulsatile stimulation of the pituitary. - This leads to **downregulation and desensitization** of GnRH receptors, effectively suppressing gonadotropin (LH and FSH) release. - Suppression halts progression of pubertal development, preventing further development of **secondary sexual characteristics** and preserving final adult height potential. *Oestrogen* - Administering **oestrogen** would worsen precocious puberty by accelerating the development of secondary sexual characteristics and advancing bone age. - Oestrogen is a primary hormone responsible for female pubertal changes, so exogenous administration would **exacerbate** the condition. *Gonadotropin-Releasing Hormone (GnRH)* - Native **GnRH** is not used for treatment because it requires **pulsatile administration** to maintain normal function, which would stimulate (not suppress) gonadotropin release. - Without the continuous receptor exposure that causes downregulation, native GnRH would promote rather than suppress pubertal progression. - Treatment requires **GnRH agonists (LHRH analogs)** that provide sustained receptor stimulation leading to desensitization. *Testosterone* - Administering **testosterone** would accelerate precocious puberty, especially in males, leading to early development of male secondary sexual characteristics. - Testosterone would advance bone age prematurely, potentially compromising the child's **final adult height**.

Q: Which of the following is the drug of choice for the syndrome of inappropriate secretion of antidiuretic hormone (SIADH)?

Demeclocycline. ***Demeclocycline*** - **Demeclocycline** is a **tetracycline antibiotic** that induces **nephrogenic diabetes insipidus**, making the renal tubules less responsive to ADH. - This effect helps in treating SIADH by promoting water excretion and correcting **hyponatremia**. *Vasopressin* - **Vasopressin** (ADH) is the hormone that is excessively secreted in SIADH, leading to water retention. - Administering vasopressin would **aggravate** SIADH symptoms by increasing water reabsorption. *Thiazide diuretic* - **Thiazide diuretics** can worsen hyponatremia in SIADH by causing **sodium loss** and **reducing free water clearance**. - Volume depletion from thiazides can paradoxically enhance ADH activity, making them contraindicated in SIADH. *Chlorpropamide* - **Chlorpropamide** is a **sulfonylurea** that can actually **potentiate ADH action**, thereby worsening SIADH. - It works by increasing the sensitivity of renal tubules to vasopressin, which is counterproductive in SIADH management.

Q: What is the primary condition for which calcitriol is used as a treatment?

Secondary hyperparathyroidism. Secondary hyperparathyroidism - Calcitriol is the active form of vitamin D (1,25-dihydroxyvitamin D₃), and it is crucial for regulating calcium and phosphate levels in the body [1]. - In secondary hyperparathyroidism, often seen in chronic kidney disease (CKD), the kidneys cannot convert vitamin D to its active form, leading to hypocalcemia and increased PTH secretion [1], [2]. - Calcitriol supplementation helps to increase calcium absorption from the gut and suppress the release of parathyroid hormone (PTH), thereby treating the underlying cause of secondary hyperparathyroidism [1], [2]. - This is the primary therapeutic indication for calcitriol in clinical practice. Lichen planus - This is a chronic inflammatory condition affecting the skin, hair, nails, and mucous membranes - Typically treated with corticosteroids or other immunosuppressants - Calcitriol has no primary role in the treatment of lichen planus; its therapeutic applications are predominantly related to calcium and bone metabolism Pemphigus - Pemphigus is a group of rare autoimmune blistering diseases that affect the skin and mucous membranes - Primary treatment involves immunosuppressants like corticosteroids, often in high doses - Calcitriol is not indicated for the treatment of pemphigus, as its mechanism of action is unrelated to the autoimmune processes characteristic of this disease Leprosy - Leprosy is a chronic infectious disease caused by the bacterium Mycobacterium leprae - Treated with multi-drug therapy (MDT), which includes antibiotics like rifampicin, dapsone, and clofazimine - Calcitriol is not an antibiotic and therefore has no role in treating the bacterial infection responsible for leprosy

Q: Which of the following is preferred for infertility treatment of a female with increased prolactin levels?

Cabergoline. ***Cabergoline*** - **Cabergoline** is a **dopamine agonist** that is highly effective in normalizing prolactin levels and restoring fertility in women with hyperprolactinemia. - It has a **longer half-life** and is generally associated with **fewer side effects** compared to other dopamine agonists, allowing for less frequent dosing (once or twice weekly). *Dopamine* - While **dopamine** itself is the natural inhibitor of prolactin secretion, it has a **very short half-life** and cannot be administered orally as a long-term treatment. - It is typically used as an IV pressor agent in critical care and is not suitable for treating chronic hyperprolactinemia. *Carbidopa* - **Carbidopa** is a **decarboxylase inhibitor** used to prevent the peripheral metabolism of levodopa, allowing more levodopa to reach the brain. - It is primarily used in the treatment of **Parkinson's disease** and has no direct role in lowering prolactin levels. *Bromocriptine* - **Bromocriptine** is also a **dopamine agonist** used to treat hyperprolactinemia, but it typically requires **daily dosing** and is associated with a higher incidence of side effects like nausea and dizziness. - While effective, **cabergoline** is generally preferred due to its better tolerability and convenience.

Q: Metyrosine is used in the treatment of?

Pheochromocytoma. ***Pheochromocytoma*** - **Metyrosine** inhibits **tyrosine hydroxylase**, the rate-limiting enzyme in **catecholamine synthesis**, thus reducing the production of **epinephrine** and **norepinephrine**. - Its primary use is in the preoperative management of **pheochromocytoma** to prevent **hypertensive crises** during surgery, and in patients with inoperable or metastatic disease to control symptoms. *Acromegaly* - **Acromegaly** is characterized by excessive **growth hormone** production. - Treatment typically involves **somatostatin analogs**, **GH receptor antagonists**, or surgery, not metyrosine. *Cushing syndrome* - **Cushing syndrome** results from prolonged exposure to **high cortisol levels**. - Management focuses on reducing **cortisol** production or surgical removal of the underlying cause, not primarily involving metyrosine. *Addison's disease* - **Addison's disease** is caused by **adrenal insufficiency** leading to deficient **cortisol** and **aldosterone**. - Treatment involves **hormone replacement therapy** with glucocorticoids and mineralocorticoids.

Q: Which oral drug is effective for the treatment of acromegaly?

Cabergoline. ***Cabergoline*** - **Cabergoline** is an oral **dopamine agonist** that can effectively suppress growth hormone (GH) secretion in a significant subset of acromegaly patients, particularly those with co-secretion of prolactin [1]. - It works by stimulating **dopamine D2 receptors** on pituitary somatotrophs, leading to a reduction in GH production [1]. *Octreotide* - **Octreotide** is a **somatostatin analog** administered via **injection** (subcutaneously or intramuscularly), not orally [3]. - Although highly effective in treating acromegaly by inhibiting GH release, its parenteral route of administration makes it unsuitable for an oral drug question [3]. *Growth hormone receptor antagonist* - **Growth hormone receptor antagonists** like **pegvisomant** act by blocking the action of GH at its receptor, but they are administered via **subcutaneous injection** [2]. - While effective in normalizing IGF-1 levels, they do not reduce GH secretion and are not available in oral form [2]. *Bromocriptine* - **Bromocriptine** is an older, first-generation **dopamine agonist** that can be taken orally [1]. - While it may lower GH levels in some acromegaly patients, its efficacy is generally **less potent and sustained** compared to cabergoline, making it a less preferred choice for primary treatment [1].

Q: What is the drug of choice for central diabetes insipidus?

Desmopressin. ***Desmopressin*** - **Desmopressin** is a synthetic analog of **vasopressin (ADH)** that selectively acts on V2 receptors in the kidney [1]. - It effectively replaces the deficient ADH in central diabetes insipidus, reducing urine output and increasing urine osmolality [1]. *Leuprolide* - **Leuprolide** is a **GnRH agonist** used to treat conditions like prostate cancer, endometriosis, and precocious puberty. - It has no role in the management of diabetes insipidus as it does not affect ADH production or action. *Thiazide diuretics* - While seemingly counterintuitive, **thiazide diuretics** are sometimes used in **nephrogenic diabetes insipidus** to reduce polyuria. - They are not the drug of choice for central diabetes insipidus because they do not address the primary deficiency of ADH. *Insulin* - **Insulin** is a hormone used to treat **diabetes mellitus**, a condition characterized by high blood glucose levels. - It has no relevance to either central or nephrogenic diabetes insipidus, which are disorders of water balance.

Q: Which of the following drugs is contraindicated in patients with diabetes and is used for the treatment of insulinoma?

Diazoxide. ***Diazoxide*** - **Diazoxide** is an **arteriolar vasodilator** that also has a potent **hyperglycemic** effect by **opening K-ATP channels** in pancreatic beta cells, which **inhibits insulin secretion**. - This mechanism makes it the drug of choice for treating **insulinoma** (where excess insulin causes hypoglycemia), but it is **absolutely contraindicated in diabetics** due to its severe hyperglycemic action. - It is the only drug among the options that satisfies both criteria: used for insulinoma AND contraindicated in diabetes. *Nicorandil* - **Nicorandil** is a **potassium channel activator** and nitrate derivative that causes vasodilation, primarily used for **angina pectoris**. - It does not inhibit insulin secretion or cause clinically significant hyperglycemia that would contraindicate its use in diabetes. - Not used for insulinoma treatment. *Minoxidil* - **Minoxidil** is a potent direct **arteriolar vasodilator** primarily used for **severe refractory hypertension** and topically for **alopecia** (hair loss). - While it can occasionally cause minor glucose intolerance, it is not contraindicated in diabetes and has no role in insulinoma treatment. *Hydralazine* - **Hydralazine** is a direct **arteriolar vasodilator** used to treat **hypertension**, particularly in pregnancy (preeclampsia/eclampsia). - It does not have significant effects on glucose metabolism or insulin secretion and is not used for insulinoma treatment.

Q: Which of the following is the synthetic form of Triiodothyronine (T3)?

Liothyronine sodium. ***Liothyronine sodium*** - This is the **synthetic form of Triiodothyronine (T3)**, the more potent and active form of thyroid hormone. - It has a **rapid onset of action** (within a few hours) and shorter half-life compared to T4. - Used in cases where direct T3 replacement is needed, such as in **myxedema coma** or for suppression testing. *Levothyroxine sodium* - This is the synthetic form of **Thyroxine (T4)**, which is then converted to T3 in peripheral tissues. - It is the **most common preparation** for treating hypothyroidism due to its longer half-life (7 days) and stable serum levels. *Liotrix* - Liotrix is a **combination preparation of synthetic T4 and synthetic T3**, typically in a 4:1 ratio. - It aims to mimic the natural physiological ratio; however, its use is **less common** than levothyroxine monotherapy. *Propylthiouracil* - This is an **antithyroid drug** used to treat hyperthyroidism, not a thyroid hormone replacement. - It works by inhibiting thyroid peroxidase and peripheral conversion of T4 to T3.

Q: Which of the following is a testosterone inhibitor?

Spironolactone. ***Spironolactone*** - Spironolactone is an **androgen receptor antagonist** and also inhibits **testosterone synthesis** by blocking 17α-hydroxylase and 17,20-lyase enzymes. - This dual action reduces the effects and production of testosterone, making it useful in conditions like **hirsutism** and **polycystic ovary syndrome (PCOS)**. *Clomiphene* - Clomiphene is a **selective estrogen receptor modulator (SERM)** that acts as an antagonist in the hypothalamus, thereby increasing the pulsatile release of GnRH. - This leads to increased FSH and LH secretion, stimulating **ovulation in women** and **testosterone production in men**, rather than inhibiting testosterone. *Bremelanotide* - Bremelanotide is a **melanocortin receptor agonist** that acts on the central nervous system to increase sexual desire. - It is used to treat **hypoactive sexual desire disorder (HSDD)** in premenopausal women and has no direct effect on testosterone levels or action. *Sildenafil* - Sildenafil is a **phosphodiesterase-5 (PDE5) inhibitor** that increases blood flow to the penis by enhancing the effects of nitric oxide, leading to an erection. - It is primarily used to treat **erectile dysfunction** and does not directly inhibit testosterone.

Question 1

Precocious puberty is treated by administering

Accepted Answer

LHRH analogs (e.g., Leuprolide)

Answer

Oestrogen

Answer

Gonadotropin-Releasing Hormone (GnRH)

Answer

Testosterone

Question 2

Which of the following is the drug of choice for the syndrome of inappropriate secretion of antidiuretic hormone (SIADH)?

Accepted Answer

Demeclocycline

Answer

Vasopressin

Answer

Thiazide diuretic

Answer

Chlorpropamide

Question 3

What is the primary condition for which calcitriol is used as a treatment?

Accepted Answer

Secondary hyperparathyroidism

Answer

Pemphigus

Answer

Lichen planus

Answer

Leprosy

Question 4

Which of the following is preferred for infertility treatment of a female with increased prolactin levels?

Accepted Answer

Cabergoline

Answer

Dopamine

Answer

Carbidopa

Answer

Bromocriptine

Question 5

Metyrosine is used in the treatment of?

Accepted Answer

Pheochromocytoma

Answer

Cushing syndrome

Answer

Addison's disease

Answer

Acromegaly

Question 6

Which oral drug is effective for the treatment of acromegaly?

Accepted Answer

Cabergoline

Answer

Bromocriptine

Answer

Octreotide

Answer

Growth hormone receptor antagonist

Question 7

What is the drug of choice for central diabetes insipidus?

Accepted Answer

Desmopressin

Answer

Leuprolide

Answer

Insulin

Answer

Thiazide diuretics

Question 8

Which of the following drugs is contraindicated in patients with diabetes and is used for the treatment of insulinoma?

Accepted Answer

Diazoxide

Answer

Nicorandil

Answer

Minoxidil

Answer

Hydralazine

Question 9

Which of the following is the synthetic form of Triiodothyronine (T3)?

Accepted Answer

Liothyronine sodium

Answer

Levothyroxine sodium

Answer

Liotrix

Answer

Propylthiouracil

Question 10

Which of the following is a testosterone inhibitor?

Accepted Answer

Spironolactone

Answer

Clomiphene

Answer

Bremelanotide

Answer

Sildenafil

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

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