Endocrine Pharmacology — MCQs

Endocrine Pharmacology Indian Medical PG Practice Questions and MCQs

Question 221: Which of the following medications are used in the treatment of postmenopausal osteoporosis?

A. Tamoxifen
B. Progesterone
C. Estrogen
D. Alendronate (Correct Answer)

Explanation: **Explanation:** **Correct Option: D (Alendronate)** Alendronate is a **Bisphosphonate**, which is the first-line pharmacological treatment for postmenopausal osteoporosis. It works by inhibiting **osteoclast-mediated bone resorption**. Bisphosphonates are structural analogs of pyrophosphate; they bind to hydroxyapatite crystals in the bone and inhibit the enzyme **farnesyl pyrophosphate synthase**, leading to osteoclast apoptosis and increased Bone Mineral Density (BMD). **Analysis of Incorrect Options:** * **A. Tamoxifen:** This is a Selective Estrogen Receptor Modulator (SERM) used primarily in breast cancer. While it has pro-estrogenic effects on bone, **Raloxifene** is the specific SERM preferred for osteoporosis because it does not increase the risk of endometrial cancer. * **B. Progesterone:** Progesterone alone does not have a significant role in increasing BMD or treating osteoporosis. It is primarily used in Hormone Replacement Therapy (HRT) to counteract the stimulatory effects of estrogen on the endometrium. * **C. Estrogen:** While Estrogen Replacement Therapy (ERT) is effective in preventing bone loss, it is no longer the first-line treatment for osteoporosis due to the increased risk of breast cancer, stroke, and thromboembolism (as per WHI guidelines). **High-Yield Clinical Pearls for NEET-PG:** * **Administration:** Alendronate must be taken on an empty stomach with a full glass of water, and the patient must remain upright for 30 minutes to prevent **erosive esophagitis**. * **Adverse Effects:** Long-term use is associated with **Osteonecrosis of the Jaw (ONJ)** and atypical subtrochanteric fractures. * **Teriparatide:** A recombinant PTH analog, it is the only **anabolic agent** (stimulates bone formation) used in severe osteoporosis.

Question 222: Which of the following is NOT an indication for the use of prostaglandins?

A. Cervical ripening
B. Postpartum hemorrhage
C. Erectile dysfunction
D. Palliative treatment of patent ductus arteriosus (Correct Answer)

Explanation: **Explanation:** The correct answer is **D (Palliative treatment of patent ductus arteriosus)** because prostaglandins are used to **maintain patency** of the ductus arteriosus, not to treat a patent one. 1. **Why Option D is correct:** In neonates with duct-dependent congenital heart defects (e.g., Transposition of the Great Arteries), **Alprostadil (PGE1)** is used to keep the ductus arteriosus open (patent) to allow life-saving oxygenation. Conversely, to **close** a Patent Ductus Arteriosus (PDA), NSAIDs like **Indomethacin or Ibuprofen** are used, as they inhibit prostaglandin synthesis. 2. **Analysis of Incorrect Options:** * **Cervical Ripening:** **Dinoprostone (PGE2)** and **Misoprostol (PGE1 analog)** are standard agents used to soften the cervix and induce labor. * **Postpartum Hemorrhage (PPH):** **Carboprost (15-methyl PGF2α)** and **Misoprostol** are potent uterine stimulants used to control bleeding when oxytocin fails. * **Erectile Dysfunction:** **Alprostadil (PGE1)** can be administered via intracavernosal injection (Caverject) or intraurethral suppository (MUSE) to induce vasodilation. **High-Yield Clinical Pearls for NEET-PG:** * **Latanoprost/Bimatoprost (PGF2α):** First-line for Glaucoma (increases uveoscleral outflow). * **Misoprostol:** Used for NSAID-induced peptic ulcers and medical abortion (combined with Mifepristone). * **Epoprostenol (PGI2):** Used in Pulmonary Arterial Hypertension. * **Side Effect Note:** Carboprost is contraindicated in **Asthma** (causes bronchoconstriction), while PGE2/PGE1 are generally safe.

Question 223: Which of the following hormones exhibits the highest mineralocorticoid activity?

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

Explanation: **Explanation:** The question asks for the hormone with the **highest mineralocorticoid activity**. In the human body, **Aldosterone** is the primary endogenous mineralocorticoid produced by the *zona glomerulosa* of the adrenal cortex [1]. It acts on the distal convoluted tubules and collecting ducts of the kidney to promote sodium reabsorption and potassium/hydrogen excretion [3]. **Analysis of Options:** * **A. Aldosterone (Correct):** It is the "gold standard" for mineralocorticoid activity. While fludrocortisone is more potent on a milligram-to-milligram basis as a drug, Aldosterone is the physiological hormone defined by this specific activity [3]. * **B. Prednisolone:** This is a synthetic glucocorticoid with intermediate anti-inflammatory potency. It possesses some mineralocorticoid activity (ratio of 0.8 compared to cortisol), but it is significantly lower than aldosterone. * **C. Fludrocortisone:** This is a synthetic corticosteroid with very high mineralocorticoid potency. While it is the drug of choice for replacement therapy in Addison’s disease due to its salt-retaining properties, it is technically a derivative designed to mimic aldosterone. * **D. Dexamethasone:** This is a highly potent, long-acting glucocorticoid [1]. It is unique because it has **zero** (negligible) mineralocorticoid activity, making it ideal for treating cerebral edema without causing salt retention. **High-Yield Clinical Pearls for NEET-PG:** 1. **Mineralocorticoid Potency:** Fludrocortisone > Aldosterone > Cortisol > Prednisolone > Dexamethasone (Zero). 2. **Glucocorticoid Potency:** Dexamethasone > Betamethasone > Triamcinolone > Prednisolone > Cortisol. 3. **DOCA (Desoxycorticosterone acetate):** Another pure mineralocorticoid, but less potent than aldosterone [2]. 4. **Spironolactone:** A competitive antagonist of the mineralocorticoid receptor used in primary hyperaldosteronism (Conn’s Syndrome).

Question 224: A 48-year-old male patient, known diabetic on insulin with truncal obesity, presents for a routine checkup. The agent used in the treatment of this patient has all the following actions except?

A. It inhibits the release of free fatty acids (FFA) from adipose tissue.
B. It enhances the uptake of glucose into adipose cells via the GLUT4 transporter.
C. In adipose tissue, it inhibits the activity of hormone-sensitive lipase.
D. Adipose tissue is less sensitive to it than many other tissues. (Correct Answer)

Explanation: ### Explanation The patient described is a diabetic on **Insulin**. This question tests your understanding of insulin’s metabolic effects on adipose tissue. [2] **Why Option D is the Correct Answer (The "Except" statement):** In reality, **adipose tissue is highly sensitive to insulin**, even more so than the liver or skeletal muscle in certain metabolic pathways. Very low concentrations of insulin are sufficient to inhibit lipolysis in adipocytes. Therefore, stating that adipose tissue is "less sensitive" is physiologically incorrect. **Analysis of Incorrect Options (Correct actions of Insulin):** * **Option A:** Insulin is a potent **anti-lipolytic hormone**. It inhibits the breakdown of triglycerides, thereby reducing the release of free fatty acids (FFA) into the circulation. [1] * **Option B:** Insulin promotes glucose uptake in adipose tissue and skeletal muscle by inducing the translocation of **GLUT4** (the insulin-dependent glucose transporter) from intracellular vesicles to the plasma membrane. [3] * **Option C:** Insulin inhibits **Hormone-Sensitive Lipase (HSL)**, the enzyme responsible for mobilizing stored fats. Simultaneously, it stimulates *Lipoprotein Lipase (LPL)* to promote fat storage. [1] **High-Yield Clinical Pearls for NEET-PG:** * **GLUT Transporters:** Remember GLUT4 is insulin-dependent (Muscle/Fat), while GLUT2 is insulin-independent (Liver/Pancreas/Kidney). [1] * **Weight Gain:** Insulin is an anabolic hormone; it promotes lipogenesis and inhibits lipolysis, which is why weight gain (truncal obesity) is a common side effect of insulin therapy. [2] * **Potassium Shift:** Insulin drives $K^+$ into cells by stimulating the $Na^+/K^+$ ATPase pump (used clinically to treat hyperkalemia). [3] * **Key Enzyme Regulation:** Insulin **dephosphorylates** enzymes (usually activating rate-limiting steps in glycolysis and inhibiting them in gluconeogenesis). [1]

Question 225: All of the following statements are true except:

A. Oxytocin sensitivity is increased during delivery
B. Prostaglandins may be given for inducing abortion during the third trimester
C. In lactating women, genital stimulation enhances oxytocin release
D. Oxytocin is used for inducing abortion in the first trimester (Correct Answer)

Explanation: **Explanation:**The correct answer is **D** because **Oxytocin is ineffective for inducing abortion in the first trimester.** **1. Why Option D is the Correct Answer (The "Except" statement):**Oxytocin requires the presence of oxytocin receptors on the myometrium to exert its contractile effect. In early pregnancy (first trimester), the density of these receptors is very low. Sensitivity to oxytocin only increases significantly after 20 weeks of gestation, peaking at term. Therefore, it cannot be used as a primary agent for first-trimester abortions; instead, drugs like **Mifepristone** and **Misoprostol** (Prostaglandins) are used [2].**2. Analysis of Other Options:** * **Option A:** True. Estrogen levels rise toward the end of pregnancy, which upregulates oxytocin receptors, making the uterus highly sensitive to even small doses of oxytocin during delivery [1]. * **Option B:** True. Prostaglandins (like PGE2/Dinoprostone or PGF2α/Carboprost) can cause uterine contractions at any stage of pregnancy, regardless of receptor density. They are used for mid-trimester and third-trimester inductions [2]. * **Option C:** True. Oxytocin release is part of a neuroendocrine reflex. While nipple stimulation is the classic trigger (Milk Ejection Reflex), genital stimulation (Ferguson Reflex) also triggers the posterior pituitary to release oxytocin.**3. NEET-PG High-Yield Pearls:** * **Drug of Choice (DOC):** Oxytocin is the DOC for **Induction of Labor** and **Postpartum Hemorrhage (PPH)** [3]. * **Half-life:** Very short (approx. 5–6 minutes); administered via IV infusion for controlled labor induction. * **Side Effects:** High doses can lead to **water intoxication** (due to its structural similarity to ADH) and uterine rupture. * **Contraindication:** Do not use in fetal distress, malpresentation, or previous C-section (risk of rupture).

Question 226: Which of the following is NOT a side effect of steroids given in anti-inflammatory dosages?

A. Diabetes mellitus
B. Hyperkalemia (Correct Answer)
C. Osteoporosis
D. Na+ and water retention

Explanation: Glucocorticoids (steroids) exert significant metabolic and mineralocorticoid effects when used in anti-inflammatory dosages. Understanding their impact on electrolytes and metabolism is crucial for the NEET-PG exam. ### **Why Hyperkalemia is the Correct Answer** Steroids do **not** cause hyperkalemia; instead, they cause **hypokalemia**. Glucocorticoids have a cross-reactivity with mineralocorticoid receptors (aldosterone receptors) in the distal renal tubules. This leads to the activation of the Na+/K+ pump, resulting in sodium reabsorption and the **excretion of potassium (K+) and hydrogen ions (H+)**. Therefore, steroid therapy is associated with hypokalemic alkalosis, not hyperkalemia. ### **Explanation of Incorrect Options** * **A. Diabetes Mellitus:** Steroids are "diabetogenic." They increase gluconeogenesis in the liver and decrease peripheral glucose uptake (insulin resistance), leading to hyperglycemia and steroid-induced diabetes. * **C. Osteoporosis:** Steroids inhibit osteoblast activity, enhance osteoclast activity, and decrease intestinal calcium absorption. This makes osteoporosis one of the most serious long-term side effects. * **D. Na+ and Water Retention:** Due to their mineralocorticoid-like action, steroids promote sodium and water retention, which can lead to edema and hypertension. ### **High-Yield Clinical Pearls for NEET-PG** * **Most common side effect (Long-term):** Osteoporosis (Prophylaxis with Bisphosphonates is often recommended). * **Ocular side effects:** Glaucoma (due to increased intraocular pressure) and Posterior Subcapsular Cataracts. * **Hematological effect:** Steroids cause **lymphopenia** and **eosinopenia** but lead to **neutrophilia** (due to demargination of neutrophils from blood vessel walls). * **Growth:** Steroids cause growth retardation in children by inhibiting growth hormone axis and direct effects on epiphyseal plates.

Question 227: Anabolic steroids may produce the following side effects except?

A. Precocious puberty in children
B. Cholestatic jaundice
C. Delayed closure of epiphysis in children (Correct Answer)
D. Acne in males and females

Explanation: Anabolic steroids are synthetic derivatives of testosterone designed to maximize anabolic effects (muscle building) while minimizing androgenic effects. However, they carry a significant side-effect profile due to their hormonal nature. **Why Option C is the Correct Answer:** Anabolic steroids do **not** cause delayed closure of the epiphysis; rather, they cause **premature closure of the epiphysis**. In children and adolescents, high levels of androgens (or their conversion into estrogens) accelerate the fusion of the epiphyseal growth plates. This leads to a sudden growth spurt followed by a permanent cessation of linear growth, ultimately resulting in short stature [3]. **Analysis of Incorrect Options:** * **A. Precocious Puberty:** In children, exogenous androgens trigger the development of secondary sexual characteristics (e.g., pubic hair, deepening of voice) prematurely, leading to isosexual precocity [1]. * **B. Cholestatic Jaundice:** 17-α alkylated steroids (like Oxymetholone or Methyltestosterone) are particularly hepatotoxic. They can cause intrahepatic cholestasis, peliosis hepatis (blood-filled cysts in the liver), and an increased risk of hepatic carcinoma [1]. * **D. Acne:** Androgens stimulate the sebaceous glands to produce excess sebum, which leads to acne in both males and females [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Virilization:** In females, anabolic steroids cause hirsutism, clitoral hypertrophy, and menstrual irregularities [1]. * **Azoospermia:** In males, exogenous steroids suppress the Hypothalamic-Pituitary-Gonadal (HPG) axis via negative feedback, leading to testicular atrophy and infertility [1], [2]. * **Lipid Profile:** They typically decrease HDL and increase LDL, significantly raising cardiovascular risk [1]. * **Psychiatric Effects:** High doses are associated with "Roid Rage" (increased aggression and irritability) [1].

Question 228: Which vitamin deficiency is most commonly seen in a pregnant mother who is on phenytoin therapy for epilepsy?

A. Vitamin B6
B. Vitamin B12
C. Vitamin A
D. Folic acid (Correct Answer)

Explanation: **Explanation:** Phenytoin is a classic inducer of hepatic cytochrome P450 enzymes and is well-known for its interference with folate metabolism. **Why Folic Acid is Correct:** Phenytoin causes **Folic acid deficiency** through three primary mechanisms: 1. **Inhibition of intestinal absorption:** It inhibits the enzyme intestinal conjugase, which is required to convert dietary polyglutamates into absorbable monoglutamates. 2. **Increased catabolism:** It induces hepatic enzymes that accelerate the breakdown of folate. 3. **Antagonism:** It acts as a weak competitive antagonist of folate. In pregnancy, this deficiency is particularly critical as it significantly increases the risk of **Neural Tube Defects (NTDs)** and can lead to megaloblastic anemia in the mother. **Why Other Options are Incorrect:** * **Vitamin B6 (Pyridoxine):** Deficiency is classically associated with **Isoniazid (INH)** therapy (due to the formation of hydrazones), not phenytoin. * **Vitamin B12:** While B12 deficiency also causes megaloblastic anemia, phenytoin specifically targets folate pathways. B12 levels are generally unaffected by anticonvulsants. * **Vitamin A:** Phenytoin does not interfere with the absorption or metabolism of fat-soluble Vitamin A. **NEET-PG High-Yield Pearls:** * **Fetal Hydantoin Syndrome:** Characterized by cleft lip/palate, microcephaly, and hypoplastic phalanges/nails. * **Vitamin K Deficiency:** Phenytoin can also cause Vitamin K deficiency in the neonate, leading to **neonatal coagulation defects**. Prophylactic Vitamin K is often given to the mother in the last month of pregnancy. * **Management:** Pregnant women on phenytoin should receive high-dose folic acid (5 mg/day) to reduce the risk of NTDs.

Question 229: Radioiodine is preferred for the treatment of which of the following conditions?

A. Young patient
B. Pregnancy
C. Recent onset of toxic goiter
D. Diffuse toxic goiter in patients > 45 years old (Correct Answer)

Explanation: **Explanation:** Radioactive Iodine (RAI), specifically **$^{131}I$**, is a definitive treatment for hyperthyroidism. It works by emitting **beta particles**, which travel a short distance (0.5–2 mm) to selectively destroy thyroid follicular cells without damaging surrounding structures like the parathyroid glands. **Why Option D is Correct:** Radioiodine is the treatment of choice for **older patients (>35–45 years)** with diffuse toxic goiter (Graves' disease) or toxic multinodular goiter. In this age group, the risk of potential genetic damage or carcinogenesis (though largely theoretical) is minimal, and RAI provides a non-invasive, permanent cure compared to long-term antithyroid drugs. **Why Other Options are Incorrect:** * **A. Young Patients:** Surgery or antithyroid drugs (Methimazole) are generally preferred in children and adolescents to avoid long-term radiation exposure to developing tissues. * **B. Pregnancy:** **Absolute Contraindication.** RAI crosses the placenta and can destroy the fetal thyroid gland, leading to cretinism. It is also contraindicated in breastfeeding. * **C. Recent onset of toxic goiter:** In new-onset cases, especially in younger patients, a trial of antithyroid drugs (ATDs) is usually the first line to see if remission can be achieved before opting for permanent ablation. **High-Yield Clinical Pearls for NEET-PG:** * **Isotope used:** $^{131}I$ (Physical half-life: 8 days). * **Primary effect:** Beta rays (destruction); Gamma rays (used for imaging). * **Most common side effect:** Delayed hypothyroidism (requires lifelong Levothyroxine). * **Pre-treatment:** In elderly patients or those with cardiac issues, render them euthyroid with ATDs *before* RAI to prevent a Thyroid Storm caused by the release of stored hormones. * **Contraindication:** Severe Graves' ophthalmopathy (RAI can worsen the condition).

Question 230: Which of the following drugs can be given safely in pregnancy?

A. Propylthiouracil (Correct Answer)
B. Methotrexate
C. Warfarin
D. Tetracycline

Explanation: **Explanation:** The management of hyperthyroidism in pregnancy requires careful selection of antithyroid drugs (ATDs). **Propylthiouracil (PTU)** is the preferred drug during the **first trimester** of pregnancy. **Why PTU is the correct answer:** PTU is highly protein-bound and less lipid-soluble compared to Methimazole. Consequently, it crosses the placenta less readily. More importantly, Methimazole is associated with specific teratogenic effects known as "Methimazole Embryopathy" (including *Aplasia Cutis* and *Choanal Atresia*). Therefore, PTU is used in the first trimester to minimize fetal risk, although a switch to Methimazole is often recommended in the second and third trimesters to avoid PTU-induced maternal hepatotoxicity. **Why other options are incorrect:** * **Methotrexate:** A potent folic acid antagonist and a known teratogen. It causes "Fetal Methotrexate Syndrome," characterized by skeletal deformities, craniofacial defects, and CNS anomalies. * **Warfarin:** Crosses the placenta and causes "Fetal Warfarin Syndrome" (Conradi-Hünermann syndrome), presenting with nasal hypoplasia and stippled epiphyses. Heparin (LMWH) is the preferred anticoagulant in pregnancy. * **Tetracycline:** These drugs chelate calcium and deposit in developing bones and teeth, leading to permanent tooth discoloration (yellow-brown) and enamel hypoplasia. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of choice for Hyperthyroidism in 1st Trimester:** PTU. * **Drug of choice for Hyperthyroidism in 2nd/3rd Trimester:** Methimazole. * **Thyroid Storm:** PTU is preferred because it also inhibits the peripheral conversion of T4 to T3. * **Teratogen Mnemonic:** Remember **"W-A-R"** (Warfarin, Alcohol, Retinoids) as major categories to avoid.

Practice by Chapter

Hypothalamic and Pituitary Hormones

Practice Questions

Thyroid Drugs and Antithyroid Agents

Practice Questions

Insulin and Oral Hypoglycemic Agents

Practice Questions

Adrenocorticosteroids

Practice Questions

Sex Hormones: Estrogens and Progestins

Practice Questions

Androgens and Anabolic Steroids

Practice Questions

Hormonal Contraceptives

Practice Questions

Drugs Affecting Calcium Metabolism

Practice Questions

Drugs for Osteoporosis

Practice Questions

Pharmacological Management of Obesity

Practice Questions

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