Endocrine Pharmacology — MCQs

Endocrine Pharmacology Indian Medical PG Practice Questions and MCQs

Question 581: What is a common side effect of thiazolidinediones?

A. Dysgeusia
B. Hypoglycemia
C. Water retention with weight gain (Correct Answer)
D. Anemia

Explanation: ### Explanation **Thiazolidinediones (TZDs)**, such as Pioglitazone and Rosiglitazone, are PPAR-γ (Peroxisome Proliferator-Activated Receptor gamma) agonists. They act primarily by increasing insulin sensitivity in peripheral tissues (adipose, muscle, and liver). **Why Option C is Correct:** The most characteristic side effect of TZDs is **fluid retention (edema) and weight gain**. This occurs because PPAR-γ receptors are also expressed in the collecting ducts of the nephron. Activation of these receptors leads to increased sodium and water reabsorption (via ENaC channels). This fluid overload can precipitate or worsen **congestive heart failure (CHF)**, making it a major contraindication in patients with NYHA Class III or IV heart failure. **Analysis of Incorrect Options:** * **A. Dysgeusia:** This (metallic taste) is a classic side effect of **Metformin**, not TZDs. * **B. Hypoglycemia:** TZDs are "euglycemics." Since they enhance the action of endogenous insulin rather than increasing insulin secretion, they rarely cause hypoglycemia when used as monotherapy. * **D. Anemia:** While mild hemodilutional anemia can occur due to fluid retention, it is not as clinically hallmark or frequently tested as weight gain and edema. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** PPAR-γ is a nuclear receptor; TZDs increase the expression of **GLUT-4** and adiponectin. * **Bone Health:** TZDs are associated with an increased risk of **fractures** (especially in women) due to decreased osteoblast differentiation. * **Bladder Cancer:** Pioglitazone has a controversial but noted association with an increased risk of bladder cancer (avoid in patients with active or past history of bladder cancer). * **Hepatotoxicity:** Troglitazone (the first TZD) was withdrawn due to severe liver injury; monitoring LFTs is still recommended for current TZDs.

Question 582: All of the following are used to treat hypercalcemia, EXCEPT:

A. D-penicillamine (Correct Answer)
B. Corticosteroid
C. Bisphosphonate
D. Mithramycin

Explanation: **Explanation:** Hypercalcemia is a critical metabolic emergency requiring agents that either decrease bone resorption, increase renal excretion, or decrease intestinal absorption of calcium. **Why D-penicillamine is the correct answer:** D-penicillamine is a **chelating agent** primarily used in the treatment of **Wilson’s disease** (to remove copper), cystinuria, and severe rheumatoid arthritis. It has no clinical role in the management of hypercalcemia. **Analysis of incorrect options (Agents used in Hypercalcemia):** * **Corticosteroids (Option B):** These are particularly effective in hypercalcemia associated with **sarcoidosis, vitamin D intoxication, and lymphomas**. They work by decreasing the intestinal absorption of calcium and inhibiting the expression of 1-alpha-hydroxylase. * **Bisphosphonates (Option C):** (e.g., Zoledronate, Pamidronate) These are the **drugs of choice** for malignancy-associated hypercalcemia. They act by inhibiting osteoclast activity, thereby reducing bone resorption. * **Mithramycin (Plicamycin) (Option D):** This is a cytotoxic antibiotic that inhibits osteoclast function. While effective for refractory hypercalcemia, its use is limited due to significant toxicity (nephrotoxicity and thrombocytopenia). **NEET-PG High-Yield Pearls:** * **Immediate Management:** The first step in severe hypercalcemia is always **aggressive IV hydration with Normal Saline**, followed by loop diuretics (Furosemide) to promote "calciuresis." * **Calcitonin:** Used for rapid reduction of calcium (works within hours) but is limited by **tachyphylaxis** (diminishing effect after 48 hours). * **Cinacalcet:** A calcimimetic used specifically for hypercalcemia in secondary hyperparathyroidism or parathyroid carcinoma. * **Denosumab:** A RANKL inhibitor used when bisphosphonates are contraindicated or ineffective.

Question 583: Which of the following has the least mineralocorticoid activity?

A. Cortisol
B. Prednisolone
C. Fludrocortisone
D. Methylprednisolone (Correct Answer)

Explanation: ### Explanation The relative potency of corticosteroids is determined by their chemical structure, which dictates their affinity for glucocorticoid (GC) versus mineralocorticoid (MC) receptors. **1. Why Methylprednisolone is correct:** Methylprednisolone is a synthetic intermediate-acting glucocorticoid. The addition of a methyl group at the C6 position significantly enhances its anti-inflammatory (glucocorticoid) potency while simultaneously **reducing its mineralocorticoid activity to near zero**. Among the options provided, it has the lowest MC-to-GC ratio (approximately 0.5 relative to cortisol's 1.0, but in clinical practice, it is considered to have negligible salt-retaining effects). **2. Analysis of Incorrect Options:** * **Cortisol (Hydrocortisone):** This is the endogenous hormone. It possesses significant mineralocorticoid activity (Ratio 1:1). It is the standard against which others are measured and causes the most salt and water retention among these options. * **Prednisolone:** A synthetic analogue of cortisol. While it has higher anti-inflammatory potency (4x), it still retains significant mineralocorticoid activity (0.8 relative to cortisol). * **Fludrocortisone:** This is a potent mineralocorticoid. It is used clinically specifically for its salt-retaining properties (e.g., in Addison’s disease). Its MC potency is roughly 125–250 times that of cortisol. **3. NEET-PG High-Yield Pearls:** * **Zero Mineralocorticoid Activity:** Dexamethasone and Betamethasone (Long-acting) have **zero** mineralocorticoid activity. If they were an option, they would be "least." * **Highest Mineralocorticoid Activity:** Fludrocortisone (Synthetic) and Aldosterone (Endogenous). * **Potency Mnemonic:** As glucocorticoid potency increases (Prednisolone < Methylprednisolone < Dexamethasone), mineralocorticoid activity generally decreases. * **Clinical Correlation:** For patients with heart failure or hypertension requiring steroids, Methylprednisolone or Dexamethasone are preferred to avoid fluid overload.

Question 584: In the treatment of congenital adrenal hyperplasia due to lack of 21 β–hydroxylase, what is the purpose of administering a synthetic glucocorticoid?

A. Inhibition of aldosterone synthesis
B. Prevention of hypoglycemia
C. Recovery of normal immune function
D. Suppression of ACTH secretion (Correct Answer)

Explanation: ### Explanation **1. Why Option D is Correct:** In 21β-hydroxylase deficiency (the most common cause of Congenital Adrenal Hyperplasia), there is a block in the conversion of precursors to **cortisol**. The resulting low serum cortisol levels trigger a compensatory increase in **ACTH (Adrenocorticotropic Hormone)** secretion from the anterior pituitary via the negative feedback loop. High ACTH levels overstimulate the adrenal cortex, leading to hyperplasia and the shunting of accumulated precursors into the **androgen pathway**. This causes virilization and ambiguous genitalia. Administering a synthetic glucocorticoid (like hydrocortisone or dexamethasone) provides the necessary negative feedback to the pituitary, **suppressing ACTH secretion**. This reduces the drive for adrenal androgen production, addressing the root cause of the clinical symptoms. **2. Why Other Options are Incorrect:** * **Option A:** Aldosterone synthesis is already impaired in 21β-hydroxylase deficiency (leading to salt-wasting). Glucocorticoids are given to replace cortisol, not to inhibit aldosterone. Mineralocorticoids (like fludrocortisone) are actually added to *supplement* aldosterone. * **Option B:** While glucocorticoids do help maintain blood glucose, the primary therapeutic goal in CAH management is the hormonal suppression of the androgenic pathway, not just glycemic control. * **Option C:** Immune function is generally not the primary concern in CAH; in fact, pharmacological doses of glucocorticoids are immunosuppressive. **3. NEET-PG High-Yield Pearls:** * **Most common enzyme deficiency:** 21β-hydroxylase (>90% of cases). * **Diagnostic marker:** Elevated levels of **17-hydroxyprogesterone (17-OHP)**. * **Clinical Triad:** Cortisol deficiency, Aldosterone deficiency (salt-wasting), and Androgen excess (virilization). * **Treatment Goal:** Use the lowest effective dose of glucocorticoids to suppress ACTH without causing iatrogenic Cushing’s syndrome or growth retardation in children.

Question 585: What is the recommended replacement dose of thyroxine?

A. 0.1 - 0.2 mg (Correct Answer)
B. 0.3 - 0.4 mg
C. 1 - 2 mg
D. 3 - 4 mg

Explanation: The correct answer is **A. 0.1 - 0.2 mg**. ### **Explanation** The goal of thyroxine (L-thyroxine) replacement therapy in hypothyroidism is to restore the patient to a euthyroid state. The standard daily maintenance dose for an average adult is approximately **1.6 µg/kg body weight**. For a typical adult weighing 60–70 kg, this calculates to roughly **100–150 µg (0.1 to 0.15 mg)** per day. Therefore, the range of **0.1 – 0.2 mg** (100–200 µg) is the clinically accepted standard for full replacement. ### **Analysis of Incorrect Options** * **B (0.3 - 0.4 mg):** This dose is excessively high for standard replacement and would likely lead to iatrogenic hyperthyroidism, increasing the risk of atrial fibrillation and osteoporosis. * **C & D (1 - 4 mg):** These doses are massive and potentially fatal. They are far beyond the physiological requirements of the human body. ### **High-Yield NEET-PG Pearls** * **Monitoring:** The best indicator for adjusting the dose in primary hypothyroidism is the **Serum TSH level**. (Target: 0.5–2.5 mIU/L). * **Administration:** Thyroxine should be taken on an **empty stomach** (30–60 minutes before breakfast) because food, calcium, and iron supplements significantly decrease its absorption. * **Special Populations:** * **Elderly/Cardiac patients:** Start with a lower dose (12.5–25 µg) to avoid precipitating angina or myocardial infarction. * **Pregnancy:** Thyroxine requirements typically **increase** by 30–50% due to increased TBG levels. * **Drug of Choice:** Levothyroxine (T4) is preferred over Liothyronine (T3) due to its longer half-life (7 days), consistent blood levels, and peripheral conversion to T3.

Question 586: Which of the following drugs is an alpha-glucosidase inhibitor?

A. Pioglitazone
B. Miglitol (Correct Answer)
C. Metformin
D. Nateglinide

Explanation: **Explanation:** **Alpha-glucosidase inhibitors (AGIs)**, such as **Miglitol** and **Acarbose**, act locally in the small intestine. They competitively inhibit the enzyme alpha-glucosidase, which is responsible for breaking down complex carbohydrates (disaccharides and oligosaccharides) into absorbable monosaccharides like glucose. By delaying carbohydrate absorption, these drugs primarily reduce **post-prandial hyperglycemia**. **Analysis of Options:** * **Miglitol (Correct):** It is a potent AGI. Unlike Acarbose, Miglitol is almost completely absorbed from the gut but is not metabolized and is excreted unchanged by the kidneys. * **Pioglitazone (Incorrect):** Belongs to the **Thiazolidinedione (TZD)** class. It acts as a PPAR-gamma agonist, increasing peripheral insulin sensitivity (primarily in adipose tissue and muscle). * **Metformin (Incorrect):** A **Biguanide** and the first-line drug for Type 2 Diabetes. Its primary mechanism is the activation of AMP-activated protein kinase (AMPK), which suppresses hepatic gluconeogenesis. * **Nateglinide (Incorrect):** A **Meglitinide analogue** (Glinide). It acts as a short-acting insulin secretagogue by closing ATP-sensitive K+ channels in pancreatic beta cells. **High-Yield Clinical Pearls for NEET-PG:** * **Side Effects:** The most common side effects of AGIs are GI-related: flatulence, bloating, and diarrhea (due to fermentation of undigested carbohydrates in the colon). * **Hypoglycemia Management:** If a patient on an AGI experiences hypoglycemia (usually due to concurrent sulfonylurea use), they must be treated with **pure glucose (dextrose)**, not sucrose (cane sugar), because AGIs block the breakdown of sucrose. * **Weight Neutrality:** AGIs are generally weight-neutral and do not cause hypoglycemia when used as monotherapy.

Question 587: Hydrocortisone acts as an anti-inflammatory agent because of the induction of the synthesis of which of the following proteins?

A. Heat shock protein 90
B. Inhibin
C. Transcortin
D. Annexin A1 (Correct Answer)

Explanation: **Explanation:** The anti-inflammatory action of glucocorticoids like **Hydrocortisone** is primarily mediated through the regulation of gene expression. When hydrocortisone binds to its intracellular glucocorticoid receptor (GR), the complex translocates to the nucleus and induces the transcription of specific anti-inflammatory proteins. **Annexin A1 (also known as Lipocortin-1)** is the most significant of these induced proteins. Its primary mechanism is the **inhibition of Phospholipase A2 (PLA2)**. By inhibiting PLA2, Annexin A1 prevents the release of arachidonic acid from the cell membrane, thereby blocking the synthesis of both prostaglandins (via the COX pathway) and leukotrienes (via the LOX pathway). This dual inhibition is what makes steroids more potent anti-inflammatory agents than NSAIDs. **Analysis of Incorrect Options:** * **A. Heat shock protein 90 (hsp90):** This protein acts as a "chaperone" that keeps the glucocorticoid receptor in an inactive state in the cytoplasm. Hydrocortisone causes the *release* of hsp90, not its synthesis. * **B. Inhibin:** This is a peptide hormone produced by the gonads to inhibit FSH secretion; it has no role in the mechanism of corticosteroids. * **C. Transcortin:** Also known as Corticosteroid Binding Globulin (CBG), this is the transport protein for cortisol in the blood. It is synthesized in the liver, not induced by hydrocortisone as part of its anti-inflammatory effect. **High-Yield Clinical Pearls for NEET-PG:** * **Genomic vs. Non-genomic:** Annexin A1 induction is a **genomic effect** (takes time). * **NF-κB Inhibition:** Glucocorticoids also suppress inflammation by inhibiting the transcription factor NF-κB, which reduces the production of pro-inflammatory cytokines (IL-1, TNF-α). * **Metabolic Side Effects:** Remember that while they suppress inflammation, they induce enzymes for gluconeogenesis, leading to hyperglycemia (Steroid Diabetes).

Question 588: What is the corticosteroid of choice in acute adrenal insufficiency?

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

Explanation: **Explanation:** **1. Why Hydrocortisone is the Correct Answer:** In acute adrenal insufficiency (Addisonian crisis), there is a life-threatening deficiency of both **glucocorticoids** (cortisol) and **mineralocorticoids** (aldosterone). Hydrocortisone is the drug of choice because it possesses significant activity at both receptors (Glucocorticoid:Mineralocorticoid potency ratio of **1:1**). Its rapid onset of action when given intravenously and its ability to mimic the body’s natural cortisol secretion make it ideal for stabilizing hemodynamics and correcting electrolyte imbalances (hyponatremia and hyperkalemia) simultaneously. **2. Analysis of Incorrect Options:** * **Fludrocortisone (A):** This is a potent mineralocorticoid used for long-term maintenance therapy. It is not used in acute crises because it lacks sufficient glucocorticoid activity and is only available in oral formulations. * **Dexamethasone (C):** While highly potent as a glucocorticoid, it has **zero mineralocorticoid activity**. It is only used in an emergency if the diagnosis of adrenal insufficiency is not yet confirmed, as it does not interfere with the measurement of serum cortisol levels (ACTH stimulation test). * **Prednisolone (D):** This has intermediate glucocorticoid potency but very low mineralocorticoid activity. It is more suitable for chronic inflammatory conditions rather than acute replacement. **3. High-Yield Clinical Pearls for NEET-PG:** * **Standard Crisis Dose:** 100 mg IV bolus of Hydrocortisone, followed by 100–200 mg every 24 hours. * **Diagnosis:** If the diagnosis is unknown, use **Dexamethasone** to allow for immediate ACTH stimulation testing. * **Maintenance:** Once stable, patients are switched to oral Hydrocortisone (divided doses) plus Fludrocortisone. * **Potency Ratio:** Remember that Hydrocortisone is the pharmaceutical equivalent of endogenous Cortisol.

Question 589: Which of the following agents is not used in the management of erectile dysfunction?

A. PGE2
B. Vardenafil
C. Phenylephrine (Correct Answer)
D. Alprostadil

Explanation: ### Explanation The management of erectile dysfunction (ED) focuses on increasing blood flow to the corpora cavernosa through vasodilation. **Phenylephrine** is the correct answer because it is a selective **$\alpha_1$-adrenergic agonist** that causes potent **vasoconstriction**. In the context of male reproductive health, phenylephrine is actually the drug of choice for treating **priapism** (a prolonged, painful erection), as it constricts the cavernous arteries to reduce blood inflow. **Analysis of Incorrect Options:** * **Vardenafil (Option B):** A potent **PDE-5 inhibitor**. It prevents the degradation of cGMP, leading to smooth muscle relaxation and increased blood flow. It is a first-line oral treatment for ED. * **Alprostadil (Option D):** This is a synthetic analogue of **PGE1**. It increases cAMP levels, causing direct vasodilation. It is administered via intracavernosal injection or intraurethral pellets (MUSE). * **PGE2 (Option A):** While PGE1 (Alprostadil) is more commonly used, PGE2 (Dinoprostone) also possesses vasodilatory properties and has historically been used in intracavernosal "cocktails" for ED, though it is now less common than PGE1. **NEET-PG High-Yield Pearls:** * **PDE-5 Inhibitors:** Sildenafil, Vardenafil, and Tadalafil (longest acting, "The Weekend Pill"). * **Contraindication:** Never co-administer PDE-5 inhibitors with **Nitrates**, as this can lead to life-threatening hypotension. * **Priapism Treatment:** If phenylephrine fails, surgical shunting may be required. * **Alprostadil:** Also used to maintain a **Patent Ductus Arteriosus (PDA)** in neonates with cyanotic heart disease.

Question 590: What is the best drug for chronic gout in a patient with renal impairment?

A. Naproxen
B. Probenecid
C. Allopurinol (Correct Answer)
D. Sulfinpyrazone

Explanation: **Explanation:** **1. Why Allopurinol is the Correct Answer:** Allopurinol is a **Xanthine Oxidase Inhibitor** that reduces the production of uric acid. In chronic gout management, it is considered the first-line urate-lowering therapy (ULT) regardless of renal function. While allopurinol metabolites are excreted renally, it remains the drug of choice in renal impairment because its dose can be safely **titrated downwards** (starting at ≤100 mg/day) to achieve target serum urate levels while monitoring for toxicity. Unlike uricosurics, its efficacy does not depend on renal clearance of uric acid. **2. Why the Other Options are Incorrect:** * **Naproxen (NSAID):** NSAIDs are used for acute gouty attacks, not chronic management. Furthermore, they are generally **contraindicated** in significant renal impairment due to the risk of acute kidney injury and fluid retention. * **Probenecid & Sulfinpyrazone (Uricosurics):** These drugs work by inhibiting the reabsorption of uric acid in the proximal tubule. They are **ineffective** when the Glomerular Filtration Rate (GFR) is low (typically <30–50 mL/min) because they cannot reach their site of action in the tubular lumen. They also increase the risk of uric acid nephrolithiasis. **3. High-Yield Clinical Pearls for NEET-PG:** * **Febuxostat:** Another Xanthine Oxidase Inhibitor; it is metabolized by the liver and is a preferred alternative if allopurinol is not tolerated in renal patients. * **HLA-B*5801:** Testing for this allele is recommended before starting Allopurinol in high-risk populations (e.g., Han Chinese, Thai) to prevent **Stevens-Johnson Syndrome/TEN**. * **Acute Attack Prophylaxis:** When starting Allopurinol, always co-administer low-dose colchicine or NSAIDs for 3–6 months to prevent "mobilization flares."

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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