Endocrine Pharmacology — MCQs

Endocrine Pharmacology Indian Medical PG Practice Questions and MCQs

Question 361: Which is the most salt-retaining glucocorticoid?

A. Hydrocortisone (Correct Answer)
B. Prednisolone
C. Betamethasone
D. Dexamethasone

Explanation: ### Explanation The correct answer is **Hydrocortisone**. **1. Why Hydrocortisone is correct:** Glucocorticoids are classified based on their relative anti-inflammatory (glucocorticoid) and salt-retaining (mineralocorticoid) potencies. **Hydrocortisone** (synthetic cortisol) is considered the standard reference with a ratio of **1:1**. Among the options provided, it has the highest mineralocorticoid activity. It acts on the distal renal tubules to promote sodium reabsorption and potassium excretion, making it the drug of choice for replacement therapy in adrenal insufficiency (Addison’s disease) where both mineralocorticoid and glucocorticoid replacement are needed. **2. Why the other options are incorrect:** * **Prednisolone:** This is an intermediate-acting steroid. It has enhanced anti-inflammatory potency (4x) but significantly **reduced** salt-retaining activity (0.8x) compared to hydrocortisone. * **Betamethasone and Dexamethasone:** These are long-acting, highly potent fluorinated steroids. They possess **zero** (negligible) salt-retaining activity. Their anti-inflammatory potency is 25–30 times that of hydrocortisone. They are preferred when fluid retention must be avoided (e.g., cerebral edema). **3. High-Yield Clinical Pearls for NEET-PG:** * **Potency Hierarchy (Salt Retention):** Hydrocortisone > Prednisolone > Dexamethasone/Betamethasone (Zero). * **Potency Hierarchy (Anti-inflammatory):** Dexamethasone > Prednisolone > Hydrocortisone. * **Drug of Choice for Congenital Adrenal Hyperplasia (CAH):** Hydrocortisone (to suppress ACTH while providing physiological replacement). * **Fetal Lung Maturity:** Betamethasone is preferred over dexamethasone because it has lower protein binding, allowing better placental transfer. * **Aldosterone:** The most potent endogenous mineralocorticoid (3000x salt retention compared to hydrocortisone), but it is not used clinically due to poor oral bioavailability.

Question 362: Which oral hypoglycemic agent is used to treat obesity?

A. Tolbutamide
B. Glipizide
C. Gliclazide
D. Metformin (Correct Answer)

Explanation: **Explanation:** **Metformin (Option D)** is the correct answer. It is a Biguanide and the first-line drug for Type 2 Diabetes Mellitus. Unlike many other antidiabetic agents, Metformin is **weight-neutral or leads to modest weight loss**. Its mechanism involves activating AMP-activated protein kinase (AMPK), which increases insulin sensitivity, decreases hepatic gluconeogenesis, and slows glucose absorption from the gut. It also suppresses appetite by increasing GLP-1 levels and GDF15 (Growth Differentiation Factor 15). Clinically, it is the preferred agent for obese diabetic patients and is used off-label for weight management in Polycystic Ovary Syndrome (PCOS). **Why the other options are incorrect:** * **Tolbutamide (Option A), Glipizide (Option B), and Gliclazide (Option C)** are all **Sulfonylureas**. Sulfonylureas work by stimulating insulin release from pancreatic beta cells (secretagogues). Because insulin is an anabolic hormone, these drugs characteristically cause **weight gain**, making them less ideal as a primary treatment for obese patients. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Metformin is the first-line drug for T2DM and PCOS-related infertility/obesity. * **Side Effects:** The most common side effects are GI-related (diarrhea, abdominal cramps). The most serious (though rare) side effect is **Lactic Acidosis**. * **Contraindication:** It should be avoided in patients with significant renal impairment (eGFR <30 mL/min) due to the risk of lactic acidosis. * **Vitamin Deficiency:** Long-term use of Metformin is associated with **Vitamin B12 deficiency**. * **Other Weight-Loss Antidiabetics:** While Metformin is the classic answer, newer agents like **GLP-1 agonists** (e.g., Liraglutide, Semaglutide) and **SGLT-2 inhibitors** (e.g., Dapagliflozin) also promote significant weight loss.

Question 363: A 46-year-old male patient has Cushing's syndrome due to an adrenal tumor. Which of the following drugs would be expected to reduce the signs and symptoms of his disease?

A. Betamethasone
B. Cortisol
C. Fludrocortisone
D. Ketoconazole (Correct Answer)

Explanation: ### Explanation **Correct Option: D. Ketoconazole** Cushing’s syndrome is characterized by excessive cortisol production. In this case, the cause is an adrenal tumor. **Ketoconazole** is an antifungal agent that, at higher doses, acts as a potent inhibitor of steroidogenesis. It inhibits several cytochrome P450 enzymes, most notably **11β-hydroxylase** and **17α-hydroxylase (17,20-lyase)**. By blocking these enzymes, it directly reduces the synthesis of cortisol in the adrenal cortex, thereby alleviating the clinical signs and symptoms of hypercortisolism. **Why other options are incorrect:** * **A. Betamethasone:** This is a potent synthetic glucocorticoid. Administering it would worsen the symptoms of Cushing’s syndrome by increasing the total glucocorticoid burden. * **B. Cortisol:** This is the endogenous glucocorticoid already in excess. Adding exogenous cortisol would exacerbate the disease. * **C. Fludrocortisone:** This is a potent mineralocorticoid used primarily for replacement therapy in adrenal insufficiency (Addison’s disease). It does not inhibit cortisol production and may worsen hypertension or hypokalemia associated with Cushing's. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** While Ketoconazole is frequently used, **Metyrapone** (inhibits 11β-hydroxylase) is often preferred for controlling hypercortisolism in pregnant women. * **Mifepristone:** A glucocorticoid receptor antagonist used for hyperglycemia in Cushing’s patients who are not surgical candidates. * **Mitotane:** An adrenolytic agent used specifically for adrenal carcinoma. * **Side Effect Note:** Ketoconazole can cause hepatotoxicity and gynecomastia (due to inhibition of androgen synthesis), which are common "catch" points in exams.

Question 364: Liothyronine is the drug of choice in the treatment of:

A. Myxedema coma (Correct Answer)
B. Cretinism
C. Iodine deficiency goiter
D. Non-resectable causes of papillary thyroid carcinoma

Explanation: **Explanation:** **Liothyronine (T3)** is the synthetic form of the naturally occurring thyroid hormone triiodothyronine. It is the drug of choice for **Myxedema coma** because it is 3 to 4 times more potent than Levothyroxine (T4) and has a significantly faster onset of action. In a life-threatening emergency like Myxedema coma, the immediate metabolic effect provided by T3 is crucial to reverse severe hypothermia and bradycardia. **Analysis of Options:** * **A. Myxedema coma (Correct):** T3 is preferred due to its rapid action and because the peripheral conversion of T4 to T3 is often impaired in critically ill patients. * **B. Cretinism:** Levothyroxine (T4) is the drug of choice. It provides a stable, long-term hormonal level necessary for brain development and growth, with a longer half-life (7 days) allowing for once-daily dosing. * **C. Iodine deficiency goiter:** The primary treatment is iodine supplementation (e.g., iodized salt) or Levothyroxine to suppress TSH levels. * **D. Papillary thyroid carcinoma:** The mainstay of treatment is surgical resection followed by radioactive iodine (I-131) and TSH suppression therapy using Levothyroxine (T4). **High-Yield NEET-PG Pearls:** * **Drug of Choice for Hypothyroidism:** Levothyroxine (T4) is preferred for routine replacement because it is cheaper, has a longer half-life, and is converted to T3 physiologically. * **Pharmacokinetics:** T3 has a shorter half-life (~1 day) and requires multiple daily doses, making it unsuitable for long-term maintenance. * **Monitoring:** TSH levels are used to monitor T4 therapy, but they are less reliable for T3 therapy. * **Cardiac Warning:** Use T3 with extreme caution in elderly patients or those with heart disease due to the risk of precipitating arrhythmias or angina.

Question 365: Denosumab, a monoclonal antibody against the RANKL receptor, is used in the treatment of which of the following conditions?

A. Rheumatoid arthritis
B. Osteoporosis (Correct Answer)
C. Osteoarthritis
D. Systemic lupus erythematosus (SLE)

Explanation: **Explanation:** **Denosumab** is a human monoclonal antibody that targets and binds to **RANKL** (Receptor Activator of Nuclear Factor kappa-B Ligand). Under normal physiological conditions, RANKL is secreted by osteoblasts and binds to RANK receptors on osteoclast precursors, leading to their maturation and activation. By inhibiting RANKL, Denosumab prevents osteoclast formation and activity, thereby decreasing bone resorption and increasing bone mineral density. * **Why Option B is correct:** Because it effectively inhibits bone resorption, Denosumab is FDA-approved for the treatment of **postmenopausal osteoporosis**, osteoporosis in men, and bone loss induced by hormone ablation therapy (e.g., in prostate or breast cancer). * **Why Options A, C, and D are incorrect:** * **Rheumatoid Arthritis (A) and SLE (D)** are systemic autoimmune inflammatory diseases. While these conditions can lead to secondary osteoporosis, Denosumab does not treat the underlying inflammatory pathology. * **Osteoarthritis (C)** is a degenerative joint disease involving cartilage breakdown, not a primary disorder of systemic bone resorption. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** It mimics the action of **Osteoprotegerin (OPG)**, the body's natural RANKL decoy receptor. * **Administration:** It is administered as a **subcutaneous injection** once every 6 months. * **Adverse Effects:** The most significant side effects include **hypocalcemia** (must check calcium levels before dosing) and, rarely, **Osteonecrosis of the Jaw (ONJ)** or atypical femur fractures. * **Other Use:** In higher doses (Xgeva), it is used for **Giant Cell Tumor of Bone** and bone metastases.

Question 366: Which of the following is NOT a glucocorticoid with minimal mineralocorticoid activity?

A. Triamcinolone
B. Betamethasone
C. Cortisol (Correct Answer)
D. Dexamethasone

Explanation: Explanation: The classification of glucocorticoids is based on their relative anti-inflammatory (glucocorticoid) versus salt-retaining (mineralocorticoid) potency. Why Cortisol is the correct answer: Cortisol (Hydrocortisone) is the naturally occurring glucocorticoid. It possesses significant mineralocorticoid activity (ratio of 1:1 for anti-inflammatory vs. salt-retaining effect). Because it causes substantial sodium and water retention, it is not considered a "selective" glucocorticoid. In clinical practice, it is used for replacement therapy in adrenal insufficiency rather than for pure anti-inflammatory purposes where edema must be avoided [1]. Why the other options are incorrect: * Triamcinolone: This is an intermediate-acting synthetic steroid with zero mineralocorticoid activity. It is highly selective for glucocorticoid receptors. * Dexamethasone & Betamethasone: These are long-acting, highly potent systemic steroids. They have the highest anti-inflammatory potency and negligible to zero mineralocorticoid activity. They are preferred when high-dose steroid therapy is needed without the risk of fluid overload or hypertension. High-Yield NEET-PG Pearls: 1. Potency Ratio: Dexamethasone is roughly 25–30 times more potent than Cortisol as an anti-inflammatory agent. 2. DOC for Fetal Lung Maturity: Betamethasone (or Dexamethasone) is used because they cross the placenta and have minimal mineralocorticoid effects. 3. Aldosterone: The primary endogenous mineralocorticoid; it has zero anti-inflammatory (glucocorticoid) activity [1]. 4. Fludrocortisone: A synthetic steroid with very high mineralocorticoid potency, used specifically for salt replacement in Addison’s disease.

Question 367: All the following are pharmacologic therapies for androgen excess except?

A. Glucocorticoids
B. Spironolactone
C. Fludrocortisone (Correct Answer)
D. Oral contraceptives

Explanation: ### Explanation The management of androgen excess (hyperandrogenism) focuses on either suppressing the production of androgens or blocking their action at the receptor level. **Why Fludrocortisone is the Correct Answer:** **Fludrocortisone** is a potent **mineralocorticoid** analog used primarily as replacement therapy in adrenal insufficiency (Addison’s disease) or salt-wasting forms of Congenital Adrenal Hyperplasia (CAH). It has no anti-androgenic properties; in fact, its role is to maintain fluid and electrolyte balance. It does not inhibit androgen synthesis or block androgen receptors. **Analysis of Incorrect Options:** * **Glucocorticoids (e.g., Dexamethasone):** These are used in cases of androgen excess caused by CAH. By providing negative feedback to the pituitary, they decrease ACTH secretion, which in turn reduces the overproduction of adrenal androgens. * **Spironolactone:** This is a potassium-sparing diuretic that also acts as a **competitive androgen receptor antagonist** and inhibits 17α-hydroxylase. It is a mainstay treatment for hirsutism in Polycystic Ovary Syndrome (PCOS). * **Oral Contraceptive Pills (OCPs):** OCPs treat androgen excess by multiple mechanisms: they suppress LH secretion (reducing ovarian androgen production), and the estrogen component increases **Sex Hormone-Binding Globulin (SHBG)**, which lowers the levels of free, biologically active testosterone. **Clinical Pearls for NEET-PG:** * **Finasteride:** A 5α-reductase inhibitor often used for hirsutism; it prevents the conversion of Testosterone to the more potent Dihydrotestosterone (DHT). * **Cyproterone Acetate:** A progestin with significant anti-androgenic activity, often found in specific OCP formulations (e.g., Diane-35) used for acne and hirsutism. * **Flutamide:** A pure non-steroidal anti-androgen; however, its use is limited by potential hepatotoxicity.

Question 368: Which of the following is not a naturally occurring estrogen?

A. Estrone
B. Estradiol
C. Estriol
D. Diethylstilbestrol (Correct Answer)

Explanation: **Explanation:** The correct answer is **D. Diethylstilbestrol (DES)**. Estrogens are classified into two categories: natural (endogenous) and synthetic. 1. **Why Diethylstilbestrol is correct:** DES is a **synthetic, non-steroidal estrogen**. Unlike natural estrogens, which have a steroid nucleus (cyclopentanoperhydrophenanthrene), DES is a phenol derivative. It was historically used to prevent miscarriages but is now largely obsolete due to its association with severe adverse effects. 2. **Why other options are incorrect:** * **Estradiol (B):** The most potent and primary estrogen produced by the ovaries in premenopausal women. * **Estrone (A):** A weaker estrogen produced primarily in adipose tissue via peripheral aromatization; it is the dominant estrogen after menopause. * **Estriol (C):** The least potent estrogen, produced in large quantities by the placenta; it serves as a marker of fetal well-being during pregnancy. **High-Yield Clinical Pearls for NEET-PG:** * **Potency Order:** Estradiol (E2) > Estrone (E1) > Estriol (E3). * **DES Side Effects:** Exposure *in utero* is famously associated with **Clear Cell Adenocarcinoma of the vagina** in female offspring ("DES daughters") and structural reproductive tract abnormalities. * **Synthetic Steroidal Estrogens:** Ethinylestradiol and Mestranol (commonly used in OCPs). * **Metabolism:** Natural estrogens have high first-pass metabolism and low oral bioavailability, whereas synthetic estrogens like DES and Ethinylestradiol are orally active.

Question 369: Medical adrenalectomy is seen with:

A. Vincristine
B. Vinblastine
C. Mitotane (Correct Answer)
D. Methotrexate

Explanation: **Explanation:** **Correct Answer: C. Mitotane** **Medical Adrenalectomy** refers to the pharmacological destruction or functional suppression of the adrenal cortex, mimicking a surgical removal. * **Mitotane** is a cytotoxic drug specifically targeted at the adrenal cortex. It is a derivative of the insecticide DDT. * **Mechanism:** It acts as an adrenolytic agent by causing selective atrophy of the *zona fasciculata* and *zona reticularis*, leading to a rapid decrease in adrenocortical hormone production. * **Clinical Use:** It is primarily used in the treatment of inoperable **Adrenocortical Carcinoma** and occasionally in refractory Cushing’s syndrome. **Why other options are incorrect:** * **Vincristine & Vinblastine (Options A & B):** These are Vinca alkaloids that inhibit microtubule polymerization (acting on the M-phase of the cell cycle). Their primary toxicities are neurological (Vincristine) and bone marrow suppression (Vinblastine), with no specific destructive effect on the adrenal glands. * **Methotrexate (Option D):** An antimetabolite that inhibits Dihydrofolate Reductase (DHFR). It is used for various cancers and autoimmune conditions but does not cause adrenal necrosis. **High-Yield Clinical Pearls for NEET-PG:** * **Other drugs causing "Medical Adrenalectomy" or suppression:** Ketoconazole (inhibits 17α-hydroxylase), Metyrapone (inhibits 11β-hydroxylase), and Aminoglutethimide. * **Mitotane Side Effect:** It is highly lipid-soluble and can cause significant GI distress and neurological symptoms (ataxia, dizziness). * **Note:** Patients on Mitotane often require lifelong glucocorticoid and mineralocorticoid replacement therapy due to the permanent destruction of the adrenal tissue.

Question 370: Tolbutamide acts by increasing what?

A. Insulin receptors
B. Glucose entry
C. Glucose absorption
D. Insulin secretion (Correct Answer)

Explanation: **Explanation:** **Mechanism of Action (Why D is correct):** Tolbutamide is a **first-generation Sulfonylurea**. These drugs act as insulin secretagogues by binding to the **Sulfonylurea Receptor-1 (SUR1)** subunit of the ATP-sensitive potassium ($K_{ATP}$) channels on the pancreatic beta-cell membrane. This binding leads to: 1. **Closure of $K_{ATP}$ channels**, preventing potassium efflux. 2. **Depolarization** of the cell membrane. 3. Opening of **voltage-gated $Ca^{2+}$ channels**, leading to calcium influx. 4. **Exocytosis of insulin** granules into the bloodstream. **Why other options are incorrect:** * **A & B:** Increasing insulin receptor sensitivity or glucose entry into peripheral tissues (like muscle and fat) is the primary mechanism of **Biguanides (Metformin)** and **Thiazolidinediones (Pioglitazone)**, not sulfonylureas. * **C:** Inhibition of glucose absorption from the gastrointestinal tract is the mechanism of **Alpha-glucosidase inhibitors** (e.g., Acarbose, Voglibose). **High-Yield Clinical Pearls for NEET-PG:** * **Generation:** Tolbutamide is a first-generation sulfonylurea with a short half-life, making it safer in elderly patients regarding prolonged hypoglycemia, though it is rarely used now. * **Prerequisite:** Since they stimulate the release of endogenous insulin, sulfonylureas require **functional beta-cells** to work; they are ineffective in Type 1 Diabetes. * **Side Effects:** The most common side effect is **hypoglycemia**. Tolbutamide can also cause a **disulfiram-like reaction** with alcohol. * **Weight Gain:** Unlike Metformin, sulfonylureas typically cause weight gain due to increased insulin levels.

Practice by Chapter

Hypothalamic and Pituitary Hormones

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Thyroid Drugs and Antithyroid Agents

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Insulin and Oral Hypoglycemic Agents

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Adrenocorticosteroids

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Sex Hormones: Estrogens and Progestins

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Androgens and Anabolic Steroids

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Hormonal Contraceptives

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Drugs Affecting Calcium Metabolism

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Drugs for Osteoporosis

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Pharmacological Management of Obesity

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