Endocrine Pharmacology — MCQs

Endocrine Pharmacology Indian Medical PG Practice Questions and MCQs

Question 191: Beta blockers are used in hyperthyroidism:

A. As short-term symptomatic therapy until the effect of carbimazole develops (Correct Answer)
B. As long-term therapy after subtotal thyroidectomy
C. In patients not responding to carbimazole
D. To potentiate the effect of radioactive iodine

Explanation: ### Explanation **1. Why Option A is Correct:** Hyperthyroidism causes a hypermetabolic state characterized by increased expression and sensitivity of **beta-adrenergic receptors**. This leads to symptoms like palpitations, tachycardia, tremors, and anxiety. Antithyroid drugs (ATDs) like **Carbimazole** have a slow onset of action, often taking **3–6 weeks** to achieve a euthyroid state because they inhibit the synthesis of new hormones but do not affect pre-existing stored hormones. Beta-blockers (specifically **Propranolol**) provide rapid symptomatic relief by blocking adrenergic overactivity. They act as a "bridge therapy" until the ATDs take full effect. **2. Why Other Options are Incorrect:** * **Option B:** After a subtotal thyroidectomy, the source of excess hormone is removed. Long-term beta-blocker therapy is unnecessary unless the patient develops permanent cardiac complications or remains thyrotoxic. * **Option C:** If a patient does not respond to Carbimazole, the definitive treatment is usually radioactive iodine (RAI) or surgery, not just beta-blockers, which do not treat the underlying thyroid hormone excess. * **Option D:** Beta-blockers do not potentiate Radioactive Iodine (RAI). In fact, they are used to control symptoms *during* the period after RAI administration, as RAI can take weeks to months to destroy thyroid tissue and may initially cause a transient release of stored hormones. **3. High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** **Propranolol** is the preferred beta-blocker because it uniquely inhibits the **peripheral conversion of T4 to T3** (at high doses). * **Thyroid Storm:** Beta-blockers are a cornerstone in managing thyroid storm to prevent high-output heart failure. * **Contraindication:** In hyperthyroid patients with **asthma**, use cardioselective beta-blockers like **Atenolol or Metoprolol** instead of Propranolol. * **Pre-operative use:** Beta-blockers are used for 7–10 days before thyroid surgery to make the patient "clinically euthyroid" and prevent intraoperative thyroid storm.

Question 192: A patient with hypothyroidism is prescribed thyroxine. Which of the following is the most reliable guide for adjustment of the thyroxine dose?

A. Pulse rate
B. Body weight
C. Serum thyroxine level
D. Serum TSH level (Correct Answer)

Explanation: **Explanation:** In the management of primary hypothyroidism, the **Serum TSH level** is the most sensitive and reliable indicator for dose titration of Levothyroxine (T4). **Why Serum TSH is the Gold Standard:** The pituitary-thyroid axis operates on a negative feedback loop. Small changes in free thyroxine (T4) levels result in logarithmic changes in TSH. Therefore, TSH reflects the adequacy of thyroid hormone replacement at the cellular level. The goal of therapy is to normalize TSH (typically between 0.5 to 2.5 mIU/L). **Analysis of Incorrect Options:** * **A. Pulse rate:** While tachycardia can indicate over-replacement (thyrotoxicosis), it is non-specific and can be influenced by anxiety, medications (beta-blockers), or cardiac disease. * **B. Body weight:** Weight loss is a clinical sign of improvement, but it is too subjective and slow to serve as a precise guide for pharmacological titration. * **C. Serum thyroxine level:** Measuring T4 is less reliable because exogenous T4 levels can fluctuate based on the timing of the last dose. Furthermore, TSH is a more sensitive marker for detecting subclinical over- or under-replacement. **High-Yield Clinical Pearls for NEET-PG:** * **Steady State:** After starting or changing a dose, TSH should be measured only after **6–8 weeks**, as this is the time required to reach a new steady state. * **Exception:** In **Secondary (Central) Hypothyroidism** (pituitary/hypothalamic disease), TSH is unreliable. In these cases, **Free T4** is used to monitor therapy. * **Pregnancy:** T4 requirements typically **increase** by 30-50% during pregnancy; TSH should be monitored closely. * **Administration:** Levothyroxine should be taken on an empty stomach (30-60 mins before breakfast) to ensure optimal absorption.

Question 193: Which of the following is NOT an effect of bromocriptine?

A. Dopamine agonist
B. Increases prolactin release (Correct Answer)
C. Decreases prolactin release
D. All of the above

Explanation: **Bromocriptine** is a semi-synthetic ergot alkaloid that acts as a potent **Dopamine (D2) receptor agonist** [3]. In the neuroendocrine system, dopamine acts as the primary **Prolactin Inhibiting Hormone (PIH)**.1. **Why Option B is correct:** Bromocriptine mimics the action of dopamine in the anterior pituitary. By stimulating D2 receptors on lactotroph cells, it **inhibits** the synthesis and secretion of prolactin [2]. Therefore, saying it "increases prolactin release" is factually incorrect, making it the right choice for this "NOT" type question.2. **Why Option A is incorrect:** Bromocriptine is a direct-acting dopamine agonist [3]. This is its primary mechanism of action, used to treat conditions like Parkinson’s disease [1, 3] and hyperprolactinemia [2].3. **Why Option C is incorrect:** Decreasing prolactin release is the hallmark therapeutic effect of bromocriptine [2]. It is the drug of choice for prolactinomas and galactorrhea [2].**High-Yield Clinical Pearls for NEET-PG:** * **Clinical Uses:** Prolactinoma (shrinks tumor size) [2], Acromegaly (paradoxically decreases GH in these patients) [1], Parkinson’s disease [1, 3], and Type 2 Diabetes Mellitus (Quick-release formulation).* **Side Effects:** Nausea and vomiting (most common due to CTZ stimulation), postural hypotension, and digital vasospasm.* **Comparison:** **Cabergoline** is now preferred over Bromocriptine because it is more potent, has a longer half-life (dosed twice weekly), and has fewer gastrointestinal side effects [1].* **Contraindication:** It should be avoided in patients with a history of psychotic illness as it may exacerbate symptoms.

Question 194: Lactic acidosis is a known complication associated with which of the following medications?

A. Metformin
B. Phenformin (Correct Answer)
C. Repaglinide
D. Rosiglitazone

Explanation: **Explanation:** The correct answer is **Phenformin**. **1. Why Phenformin is the correct answer:** Phenformin and Metformin both belong to the **Biguanide** class of oral hypoglycemics. Biguanides inhibit mitochondrial respiration (Complex I), which increases anaerobic glycolysis and leads to the overproduction of lactic acid. While both drugs carry this risk, **Phenformin** has a significantly higher affinity for mitochondrial membranes and interferes more aggressively with lactate oxidation. Due to a high incidence of fatal lactic acidosis, Phenformin was withdrawn from the market in most countries in the 1970s. **2. Analysis of Incorrect Options:** * **Metformin (Option A):** While Metformin is also a biguanide, its risk of lactic acidosis is extremely low (approx. 3 cases per 100,000 patient-years) when used in patients with normal renal function. It is the first-line drug for Type 2 Diabetes. * **Repaglinide (Option C):** This is a Meglitinide analog (insulin secretagogue). Its primary side effect is hypoglycemia and weight gain, not lactic acidosis. * **Rosiglitazone (Option D):** This is a Thiazolidinedione (PPAR-γ agonist). Its major side effects include fluid retention, peripheral edema, weight gain, and potential risk of congestive heart failure. **3. NEET-PG High-Yield Pearls:** * **Mechanism of Biguanides:** Activation of AMP-activated protein kinase (AMPK), leading to decreased hepatic gluconeogenesis and increased peripheral glucose uptake. * **Metformin Contraindication:** It is contraindicated when the eGFR is <30 mL/min/1.73 m² due to the increased risk of accumulation and subsequent lactic acidosis. * **Clinical Presentation:** Lactic acidosis presents with a high anion gap, decreased blood pH, and elevated serum lactate levels. * **Drug of Choice:** Metformin remains the drug of choice for obese Type 2 DM patients as it is weight-neutral/weight-reducing.

Question 195: In post-menopausal women receiving estrogen replacement therapy, adding a progestin for 10-12 days each month is recommended primarily because the progestin:

A. Blocks the increased risk of myocardial infarction associated with estrogen therapy.
B. Blocks the increased risk of endometrial carcinoma associated with estrogen therapy. (Correct Answer)
C. Reverses vulval atrophy occurring in post-menopausal women.
D. Enhances the metabolic benefits of estrogen treatment.

Explanation: ### Explanation **1. Why Option B is Correct:** Estrogen, when administered alone (unopposed estrogen therapy), stimulates the proliferation of the endometrial lining. In post-menopausal women, this chronic stimulation leads to **endometrial hyperplasia**, which is a significant precursor to **endometrial carcinoma**. Progestins are added to the regimen for 10–12 days per cycle to counteract this effect. Progestins induce a "secretory" change in the endometrium and promote regular shedding of the lining, thereby neutralizing the mitogenic effect of estrogen and significantly reducing the risk of malignancy. **2. Why Other Options are Incorrect:** * **Option A:** Estrogen therapy is generally not used for primary prevention of MI. In fact, some studies (like the WHI) suggest that combined hormone therapy might slightly *increase* the risk of cardiovascular events in certain age groups. Progestins do not mitigate this risk; some may even negatively impact the lipid profile. * **Option C:** Both estrogen and progestin can help with urogenital symptoms, but **estrogen** is the primary hormone responsible for reversing vulvovaginal atrophy. Progestin is not required for this specific benefit. * **Option D:** Progestins often attenuate some of the metabolic benefits of estrogen (e.g., they may slightly decrease HDL or affect glucose tolerance), rather than enhancing them. **3. NEET-PG High-Yield Pearls:** * **Rule of Thumb:** If a woman has an **intact uterus**, she must receive combined therapy (Estrogen + Progestin). If she has had a **hysterectomy**, estrogen can be given alone (unopposed). * **SERMs:** Raloxifene is an alternative for post-menopausal osteoporosis as it acts as an estrogen antagonist in the uterus, thus carrying no risk of endometrial cancer. * **Side Effects:** The addition of progestin is associated with an increased risk of **breast cancer** compared to estrogen alone, which is a common "trap" in exams.

Question 196: Which of the following drugs can cause galactorrhea?

A. Bromocriptine
B. Pantoprazole
C. Metoclopramide (Correct Answer)
D. Omeprazole

Explanation: **Explanation:** The correct answer is **Metoclopramide**. **Mechanism of Action:** Prolactin secretion from the anterior pituitary is under tonic inhibition by **Dopamine** (acting on D2 receptors). Any drug that acts as a **Dopamine (D2) antagonist** removes this inhibitory effect, leading to increased prolactin levels (**Hyperprolactinemia**). Metoclopramide is a potent central and peripheral D2 receptor antagonist used as a prokinetic and antiemetic. The resulting hyperprolactinemia stimulates breast tissue, leading to **galactorrhea** (inappropriate milk secretion), gynecomastia, and menstrual irregularities. **Analysis of Options:** * **Bromocriptine (Option A):** This is a **Dopamine agonist**. It mimics dopamine's inhibitory effect on the pituitary and is actually used to *treat* hyperprolactinemia and galactorrhea. * **Pantoprazole & Omeprazole (Options B & D):** These are Proton Pump Inhibitors (PPIs). While they can cause minor GI side effects, they do not interfere with the dopaminergic pathway or prolactin secretion. **NEET-PG High-Yield Pearls:** * **Other drugs causing galactorrhea:** Antipsychotics (Haloperidol, Risperidone), Methyldopa (depletes dopamine), Reserpine, and Tricyclic Antidepressants. * **Domperidone:** Unlike Metoclopramide, it does not cross the blood-brain barrier easily, but it can still affect the pituitary (which lies outside the BBB), also potentially causing galactorrhea. * **Clinical Tip:** If a patient presents with galactorrhea and infertility, always check their medication history for prokinetics or antipsychotics before ordering advanced imaging.

Question 197: Which corticosteroid has no glucocorticoid activity?

A. Aldosterone
B. Fludrocortisone
C. DOCA (Correct Answer)
D. Cortisol

Explanation: **Explanation:** The classification of corticosteroids is based on their relative potency for **Glucocorticoid (GC)** activity (metabolic/anti-inflammatory) versus **Mineralocorticoid (MC)** activity (electrolyte/water balance). **Why DOCA is the correct answer:** **Desoxycorticosterone Acetate (DOCA)** is a precursor in the biosynthetic pathway of aldosterone. It is a **pure mineralocorticoid**. It acts exclusively on the mineralocorticoid receptors in the distal tubule to promote sodium reabsorption and potassium excretion. Crucially, it lacks the 11-OH and 17-OH groups necessary to bind to glucocorticoid receptors, resulting in **zero glucocorticoid activity**. **Analysis of Incorrect Options:** * **Aldosterone:** While it is the primary endogenous mineralocorticoid, it possesses a very negligible (trace) amount of glucocorticoid activity, though clinically insignificant. In the context of "no activity," DOCA is the more precise pharmacological answer. * **Fludrocortisone:** This is a potent synthetic steroid used for replacement therapy in Addison’s disease. It has very high MC potency but also retains **significant GC activity** (approx. 10-15 times that of cortisol). * **Cortisol (Hydrocortisone):** This is the primary endogenous glucocorticoid. It possesses a 1:1 ratio of GC to MC activity. **NEET-PG High-Yield Pearls:** * **DOCA** is used experimentally to induce hypertension in animal models. * **Dexamethasone/Betamethasone** have the highest GC potency with **zero MC activity** (the opposite of DOCA). * **Spironolactone** is the competitive antagonist for both Aldosterone and DOCA. * **Triamcinolone** is a selective GC with practically no MC activity, often used for local injections.

Question 198: What is the primary treatment for hyperphosphatemia?

A. Calcitonin
B. Sevelamer (Correct Answer)
C. Magnesium hydroxide
D. Diuretics

Explanation: Self-study of hyperphosphatemia management focuses on clinical interventions. **Explanation:** **1. Why Sevelamer is Correct:** Sevelamer is a **non-absorbable phosphate binder** used primarily in patients with Chronic Kidney Disease (CKD) on dialysis [1, 5]. It works by binding to dietary phosphate within the gastrointestinal tract, preventing its absorption and promoting excretion in the feces. Unlike older binders (like Calcium carbonate), Sevelamer is **calcium-free**, which is a significant advantage as it reduces the risk of iatrogenic hypercalcemia and subsequent metastatic vascular calcification [2]. **2. Why Other Options are Incorrect:** * **A. Calcitonin:** This hormone inhibits bone resorption and increases renal calcium excretion. It is used for hypercalcemia and Paget’s disease, not as a primary treatment for hyperphosphatemia. * **C. Magnesium hydroxide:** While magnesium can bind phosphate, it is not a primary treatment. Its use is limited by the risk of magnesium toxicity (hypermagnesemia) and its potent laxative effect. * **D. Diuretics:** While some diuretics (like Acetazolamide) can increase phosphate excretion, they are ineffective in CKD patients with failing kidneys—the population most commonly requiring treatment for hyperphosphatemia. **3. High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Sevelamer is a cross-linked polymer that acts like an ion-exchange resin. * **Pleiotropic Effects:** Beyond lowering phosphate, Sevelamer also lowers LDL cholesterol and uric acid levels. * **Other Binders:** **Lanthanum carbonate** is another non-calcium binder. **Aluminum hydroxide** is the most potent binder but is avoided long-term due to aluminum toxicity (encephalopathy and osteomalacia) [2]. * **First-line:** In CKD, the first step is dietary restriction, followed by phosphate binders taken **with meals** to maximize binding of dietary phosphorus [1].

Question 199: Which of the following is NOT a preferred site for insulin administration?

A. Buttocks
B. Thigh
C. Around the umbilicus (Correct Answer)
D. Upper arm

Explanation: ### **Explanation** The correct answer is **C. Around the umbilicus.** While the abdomen is the most preferred site for insulin administration due to its consistent and rapid absorption, the **immediate peri-umbilical area (a 2-inch or 5-cm radius around the navel)** must be avoided. This is because the umbilical area contains dense vascularity and tough cicatricial (scar) tissue, which can lead to erratic absorption and increased pain. #### **Analysis of Options:** * **Abdomen (excluding the umbilicus):** This is the site of choice for bolus/prandial insulin because it offers the fastest and most predictable absorption rate. * **Upper Arm (Option D):** The posterior aspect of the upper arm is a common site. It has a moderate absorption rate, slower than the abdomen but faster than the thighs. * **Thigh (Option B):** The anterior and lateral aspects are used. Absorption here is slower, making it suitable for basal (long-acting) insulin to prevent nocturnal hypoglycemia. * **Buttocks (Option A):** The upper outer quadrant is used. It has the slowest absorption rate among the four sites. #### **High-Yield Clinical Pearls for NEET-PG:** 1. **Absorption Speed:** Abdomen > Arm > Thigh > Buttocks. 2. **Lipohypertrophy:** Repeated injections at the exact same spot can cause fatty lumps (lipohypertrophy), which significantly delay insulin absorption. Patients must **rotate injection sites** within the same anatomical region. 3. **Exercise Effect:** Injecting into a limb that is about to be exercised (e.g., thigh before running) increases local blood flow, leading to rapid absorption and a high risk of **sudden hypoglycemia**. 4. **Depth:** Insulin should be injected into the **subcutaneous fat**. Intramuscular injection leads to faster, unpredictable action and increased pain.

Question 200: Which of the following drugs is NOT used in the treatment of obesity?

A. Orlistat
B. Sibutramine
C. Rimonabant
D. Prednisone (Correct Answer)

Explanation: ### Explanation The correct answer is **D. Prednisone**. **1. Why Prednisone is the correct answer:** Prednisone is a systemic corticosteroid used for its potent anti-inflammatory and immunosuppressive properties. Unlike the other options, it is **not** used to treat obesity; in fact, **weight gain** and central obesity (Cushingoid features) are classic side effects of chronic glucocorticoid therapy [3]. Prednisone promotes adipogenesis and increases appetite, making it contraindicated for weight loss [2]. **2. Analysis of incorrect options:** * **A. Orlistat:** A potent, reversible **gastric and pancreatic lipase inhibitor**. It prevents the hydrolysis of dietary fats (triglycerides) into absorbable free fatty acids, leading to decreased caloric absorption. It is FDA-approved for long-term obesity management. * **B. Sibutramine:** A **serotonin-norepinephrine reuptake inhibitor (SNRI)** that acts centrally to increase satiety [1]. Note: It has been withdrawn in many countries (including India and the USA) due to increased risks of cardiovascular events (MI and stroke), but it remains a classic textbook example of an anti-obesity drug. * **C. Rimonabant:** A selective **Cannabinoid-1 (CB1) receptor antagonist** [2]. It was designed to reduce appetite and cravings. However, it was withdrawn globally due to severe psychiatric side effects, including depression and suicidal ideation [2]. **3. High-Yield Clinical Pearls for NEET-PG:** * **Liraglutide & Semaglutide:** GLP-1 receptor agonists are currently the "gold standard" and high-yield for recent exams. * **Lorcaserin:** A 5-HT2C receptor agonist (withdrawn recently due to cancer risk). * **Phentermine/Topiramate:** A popular combination therapy for weight loss. * **Steatorrhea:** The most common side effect of Orlistat (due to fat malabsorption); managed by a low-fat diet and fat-soluble vitamin supplementation.

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

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free