Endocrine Pharmacology — MCQs

Endocrine Pharmacology Indian Medical PG Practice Questions and MCQs

Question 561: Shohl's solution is:

A. Sodium citrate (Correct Answer)
B. Potassium binding resin
C. Lugol iodine
D. Radio-iodine

Explanation: **Explanation:** **Shohl’s solution** is a mixture of **sodium citrate and citric acid**. It acts as a systemic alkalizing agent. When ingested, citrate is metabolized in the liver to bicarbonate, which helps neutralize excess acid in the blood and urine [2]. * **Why Option A is correct:** Shohl’s solution is primarily used in patients with **Renal Tubular Acidosis (RTA)** and to prevent the formation of calcium and uric acid kidney stones [1]. By increasing urinary pH and citrate levels, it inhibits the crystallization of stone-forming salts. * **Why Option B is incorrect:** Potassium-binding resins (e.g., Sodium Polystyrene Sulfonate or Kayexalate) are used to treat hyperkalemia by exchanging sodium for potassium in the gut. * **Why Option C is incorrect:** Lugol’s iodine is a solution of elemental iodine and potassium iodide. It is used preoperatively in hyperthyroidism (Graves' disease) to decrease the vascularity and size of the thyroid gland (Wolff-Chaikoff effect). * **Why Option D is incorrect:** Radio-iodine ($I^{131}$) is a radioactive isotope used for the definitive treatment of hyperthyroidism and thyroid carcinoma by emitting beta particles that destroy thyroid tissue. **High-Yield Clinical Pearls for NEET-PG:** * **Bicitra** is another name for Shohl’s solution. * **Polycitra** is a similar preparation containing both sodium and potassium citrate. * **Contraindication:** Shohl’s solution should be used with caution in patients on sodium-restricted diets (e.g., Heart Failure, Hypertension) due to its high sodium content. * **Drug Interaction:** Avoid co-administration with aluminum-containing antacids, as citrate significantly increases aluminum absorption, potentially leading to toxicity.

Question 562: Which of the following drugs is most likely to cause hypoglycemia when used as a monotherapy in the treatment of type 2 diabetes?

A. Acarbose
B. Glipizide (Correct Answer)
C. Metformin
D. Rosiglitazone

Explanation: **Explanation:** The correct answer is **Glipizide (Option B)**. **1. Why Glipizide is correct:** Glipizide is a **second-generation Sulfonylurea**. Its mechanism of action involves binding to the Sulfonylurea Receptor-1 (SUR1) on the pancreatic beta-cell membrane, which closes ATP-sensitive potassium channels. This leads to cell depolarization, calcium influx, and the **active secretion of insulin** regardless of blood glucose levels. Because it forces insulin release even when glucose is low, it carries a high risk of hypoglycemia, especially if a meal is missed. **2. Why the other options are incorrect:** * **Acarbose (Alpha-glucosidase inhibitor):** It works locally in the gut to delay carbohydrate absorption. It does not stimulate insulin secretion; therefore, it does not cause hypoglycemia as monotherapy. * **Metformin (Biguanide):** It is an "euglycemic" agent. It primarily decreases hepatic glucose production and improves insulin sensitivity. It does not increase insulin secretion, making the risk of hypoglycemia negligible. * **Rosiglitazone (Thiazolidinedione):** It acts as a PPAR-gamma agonist to increase peripheral insulin sensitivity. Like metformin, it does not stimulate the pancreas to release more insulin and thus does not cause hypoglycemia on its own. **3. NEET-PG High-Yield Pearls:** * **Insulin Secretagogues:** Sulfonylureas and Meglitinides (e.g., Repaglinide) are the primary classes that cause hypoglycemia because they are glucose-independent secretagogues. * **Weight Gain:** Sulfonylureas and TZDs typically cause weight gain, whereas Metformin is weight-neutral/weight-reducing. * **Drug of Choice:** Metformin remains the first-line drug for Type 2 Diabetes due to its safety profile and lack of hypoglycemic risk. * **Management:** If a patient on Acarbose develops hypoglycemia (due to concurrent use of other drugs), they must be treated with **pure glucose (dextrose)**, not sucrose (cane sugar), because Acarbose blocks the breakdown of disaccharides.

Question 563: Which of the following drugs promotes the release of endogenous insulin?

A. Acarbose
B. Glipizide (Correct Answer)
C. Metformin
D. Pioglitazone

Explanation: ### Explanation The correct answer is **Glipizide (Option B)**. #### 1. Mechanism of the Correct Answer Glipizide belongs to the **Second-generation Sulfonylureas**. These drugs are classified as **insulin secretagogues** because they directly stimulate the release of endogenous insulin from the pancreatic beta cells. * **Mechanism:** They bind to the Sulfonylurea Receptor-1 (SUR1) subunit of the **ATP-sensitive $K^+$ channels** on the beta-cell membrane. This leads to channel closure, membrane depolarization, and an influx of calcium through voltage-gated channels, which triggers the exocytosis of insulin granules. #### 2. Analysis of Incorrect Options * **Acarbose:** An **$\alpha$-glucosidase inhibitor**. It acts locally in the intestine to delay the digestion and absorption of carbohydrates, thereby reducing postprandial glucose peaks. It does not affect insulin secretion. * **Metformin:** A **Biguanide**. Its primary action is to decrease hepatic gluconeogenesis and increase peripheral insulin sensitivity via AMPK activation. It is considered "euglycemic" because it does not stimulate insulin release and thus rarely causes hypoglycemia. * **Pioglitazone:** A **Thiazolidinedione (TZD)**. It acts as an agonist at the **PPAR-$\gamma$** receptor, primarily increasing insulin sensitivity in adipose tissue, muscle, and liver. Like metformin, it does not promote insulin release. #### 3. NEET-PG High-Yield Pearls * **Secretagogues:** Only Sulfonylureas and Meglitinides (e.g., Repaglinide) directly promote insulin release. * **Side Effects:** Because they increase insulin levels regardless of blood glucose concentration, Sulfonylureas are frequently associated with **hypoglycemia** and **weight gain**. * **Excretion:** Glipizide is primarily metabolized by the liver, making it safer than Glyburide in patients with mild renal impairment. * **Prerequisite:** These drugs require functional beta cells to work; therefore, they are ineffective in Type 1 Diabetes Mellitus.

Question 564: Which of the following is FALSE regarding the management of thyroid crisis?

A. Propranolol is the first-line therapy.
B. Carbimazole may also be used. (Correct Answer)
C. SSKI blocks the release of thyroid hormone.
D. Corticosteroids decrease the peripheral conversion of T4 to T3.

Explanation: **Explanation:** Thyroid crisis (Thyroid Storm) is a life-threatening medical emergency requiring rapid suppression of thyroid hormone synthesis, release, and peripheral action. **Why Option B is the correct (False) statement:** In the management of thyroid storm, **Propylthiouracil (PTU)** is the preferred thioamide over Carbimazole or Methimazole. This is because PTU has a dual mechanism: it inhibits thyroid peroxidase (blocking synthesis) and, crucially, **inhibits the peripheral conversion of T4 to T3** via inhibition of 5’-deiodinase. Carbimazole only blocks synthesis and lacks this peripheral effect, making it less ideal in an acute crisis. **Analysis of other options:** * **Option A (Propranolol):** It is considered first-line to control life-threatening sympathetic overactivity (tachycardia, tremors). At high doses, it also inhibits the peripheral conversion of T4 to T3. * **Option C (SSKI/Lugol’s Iodine):** Saturated Solution of Potassium Iodide (SSKI) is used to block the **release** of preformed thyroid hormones (Wolff-Chaikoff effect). *Note: It must be given at least 1 hour after the first dose of PTU to prevent the iodine from being used as substrate for new hormone synthesis.* * **Option D (Corticosteroids):** Glucocorticoids (e.g., Dexamethasone or Hydrocortisone) are used because they decrease the peripheral conversion of T4 to T3 and protect against relative adrenal insufficiency associated with thyroid storm. **NEET-PG High-Yield Pearls:** * **Order of Treatment:** 1. Beta-blockers → 2. PTU → 3. Iodine (SSKI) → 4. Corticosteroids. * **Drug of choice in Pregnancy (1st Trimester):** PTU (due to Methimazole embryopathy). * **Drug of choice in Pregnancy (2nd/3rd Trimester):** Methimazole (due to PTU-induced hepatotoxicity). * **Bile acid sequestrants (Cholestyramine):** Can be used as an adjunct to reduce the enterohepatic circulation of thyroid hormones.

Question 565: In thyrotoxicosis, which of the following is not controlled by beta-blockers?

A. Anxiety
B. Tremors
C. Tachycardia
D. Oxygen consumption (Correct Answer)

Explanation: **Explanation:** In thyrotoxicosis, the clinical manifestations are driven by two distinct mechanisms: **increased sympathetic activity** (due to the upregulation of beta-adrenergic receptors) and an **increased basal metabolic rate (BMR)** (due to the direct action of thyroid hormones on mitochondria and Na+/K+ ATPase). **1. Why Oxygen Consumption is the Correct Answer:** Beta-blockers (like Propranolol) work by antagonizing the beta-adrenergic receptors. While they effectively mitigate the symptoms of sympathetic overactivity, they have **no effect on the metabolic rate** or the increased oxygen consumption induced directly by T3 and T4. The hypermetabolic state and increased heat production in thyrotoxicosis are independent of the sympathetic nervous system; therefore, beta-blockers cannot control the elevated BMR or oxygen demand. **2. Analysis of Incorrect Options:** * **Anxiety & Tremors (Options A & B):** These are neurological manifestations of increased beta-adrenergic sensitivity. Beta-blockers cross the blood-brain barrier (especially Propranolol) and block peripheral receptors to effectively reduce these symptoms. * **Tachycardia (Option C):** This is a classic sign of sympathetic overstimulation of the heart. Beta-blockers are the treatment of choice for rapid symptomatic relief of palpitations and tachycardia in hyperthyroid patients. **Clinical Pearls for NEET-PG:** * **Propranolol** is the preferred beta-blocker because it also inhibits the peripheral conversion of **T4 to T3** (at high doses). * Beta-blockers are used as "bridge therapy" while waiting for antithyroid drugs (like Methimazole) to take effect or during a **Thyroid Storm**. * **Contraindication:** Avoid beta-blockers in thyrotoxic patients with co-existing **Asthma** (use cardioselective Esmolol or Atenolol instead).

Question 566: Which ergot alkaloid is commonly used to prevent postpartum hemorrhage?

A. Methylergometrine (Correct Answer)
B. Ergotamine
C. Dihydroergotamine
D. Dihydroergotoxine

Explanation: Methylergometrine is the ergot alkaloid of choice for preventing and treating postpartum hemorrhage (PPH) [1]. Its primary mechanism involves acting as a partial agonist at α-adrenergic and 5-HT₂ receptors in the myometrium [1]. Unlike other ergots, it induces powerful, rhythmic, and sustained uterine contractions (tetanic effect), which compress the uterine blood vessels at the placental site, effectively achieving hemostasis [1]. It is preferred over ergometrine due to its higher potency and lower incidence of side effects [1].Analysis of Incorrect Options: Ergotamine: Primarily used in the acute treatment of migraine headaches [1, 2]. It is a potent vasoconstrictor but has less selective action on the uterus compared to methylergometrine [1]. Dihydroergotamine (DHE): A hydrogenated derivative of ergotamine used for migraines [2]. It is a more potent α-blocker and causes less peripheral vasoconstriction and nausea than ergotamine [2], but it lacks significant oxytocic activity [1]. Dihydroergotoxine (Codergocrine): A mixture of hydrogenated ergot alkaloids used historically for dementia and peripheral vascular diseases. It acts as a vasodilator rather than a uterine stimulant.High-Yield Clinical Pearls for NEET-PG: Route: Usually administered IM (0.2 mg). IV administration is avoided as it can cause sudden, severe hypertension. Contraindication: Absolutely contraindicated in patients with Pregnancy-induced Hypertension (PIH), Preeclampsia, and Peripheral Vascular Disease. Active Management of Third Stage of Labor (AMTSL): While Oxytocin is the first-line drug for AMTSL, Methylergometrine is a crucial second-line agent. Storage: It is light-sensitive and must be stored in dark-colored ampoules.

Question 567: Which among the following is also called "peakless" insulin analog?

A. Insulin lispro
B. Insulin glargine (Correct Answer)
C. Insulin aspart
D. Lente Insulin

Explanation: **Explanation:** **Insulin glargine** is classified as a long-acting basal insulin analog. It is referred to as **"peakless"** because of its unique pharmacokinetic profile. Upon subcutaneous injection, the acidic solution (pH 4.0) neutralizes to physiological pH, causing the insulin to microprecipitate into stable hexamers. These hexamers are released slowly and consistently into the bloodstream, providing a steady, flat concentration for up to 24 hours. This lack of a distinct peak mimics physiological basal insulin secretion and significantly reduces the risk of nocturnal hypoglycemia. **Analysis of Incorrect Options:** * **Insulin lispro & Insulin aspart (Options A & C):** These are **ultra-short-acting** insulin analogs. They are designed to have a very rapid onset and a sharp, high peak (usually within 1 hour) to control postprandial (after-meal) glucose spikes. * **Lente Insulin (Option D):** This is an **intermediate-acting** insulin (a mixture of ultralente and semilente). Unlike glargine, it has a definite peak of action (usually 6–12 hours) and a shorter duration of action (approx. 18–24 hours). **High-Yield NEET-PG Pearls:** * **Other Peakless Analogs:** Insulin **detemir** and **degludec** are also considered peakless, with degludec having the longest half-life (>40 hours). * **Modification:** Glargine is created by replacing asparagine with glycine at position A21 and adding two arginine residues to the C-terminus of the B-chain. * **Clinical Note:** Because of its acidic pH, Insulin glargine **cannot be mixed** in the same syringe with other insulins, as this would alter its absorption profile.

Question 568: Exenatide is a drug proposed for the treatment of which condition?

A. Osteoporosis
B. Diabetes mellitus (Correct Answer)
C. Hyperparathyroidism
D. Anovulatory infertility

Explanation: **Explanation:** **Exenatide** is a synthetic analogue of **Glucagon-like peptide-1 (GLP-1)**, an incretin hormone. It is primarily used in the management of **Type 2 Diabetes Mellitus**. **Why the correct answer is right:** Exenatide acts as a **GLP-1 Receptor Agonist**. It lowers blood glucose through a glucose-dependent mechanism: it stimulates insulin secretion from pancreatic beta cells and suppresses glucagon secretion from alpha cells. Additionally, it slows gastric emptying and promotes satiety, which often leads to significant weight loss—a major clinical advantage in diabetic patients. **Why the incorrect options are wrong:** * **A. Osteoporosis:** Drugs used here include Bisphosphonates, Teriparatide (PTH analogue), or Denosumab. Exenatide has no established role in bone density management. * **C. Hyperparathyroidism:** This is managed with Cinacalcet (calcimimetic) or surgery. Exenatide does not influence parathyroid hormone levels. * **D. Anovulatory infertility:** This is typically treated with Clomiphene citrate, Letrozole, or Gonadotropins to induce ovulation. **High-Yield Clinical Pearls for NEET-PG:** * **Source:** Exenatide was originally isolated from the saliva of the **Gila monster** (*Heloderma suspectum*). * **Route:** Administered via **subcutaneous injection**. * **Key Side Effects:** Nausea is the most common; however, the most serious association to remember for exams is the risk of **Acute Pancreatitis**. * **Contraindication:** It is contraindicated in patients with a personal or family history of **Medullary Thyroid Carcinoma** or MEN 2 syndrome (due to C-cell tumor risk seen in animal studies).

Question 569: Contrast enhanced 2D echocardiography is contraindicated in which of the following conditions?

A. Bronchial asthma (Correct Answer)
B. Diabetes mellitus
C. Twins
D. Hypertension

Explanation: **Explanation:** The correct answer is **Bronchial asthma**. Contrast-enhanced 2D echocardiography typically utilizes microbubble contrast agents (e.g., sulfur hexafluoride or perflutren). These agents are known to trigger hypersensitivity reactions in susceptible individuals. In patients with **Bronchial Asthma**, the administration of these contrast agents can precipitate severe bronchospasm or anaphylactoid reactions. Furthermore, since these microbubbles are cleared via the lungs, patients with underlying reactive airway disease or severe pulmonary hypertension are at a higher risk of respiratory compromise. **Analysis of Incorrect Options:** * **Diabetes mellitus:** There is no direct contraindication for microbubble contrast in diabetics. While iodinated contrast (used in CT) requires caution due to nephropathy, ultrasound contrast is not nephrotoxic. * **Twins (Pregnancy):** While caution is generally advised during pregnancy, it is not an absolute contraindication compared to the acute risk of bronchospasm in asthma. * **Hypertension:** Controlled hypertension is not a contraindication. However, unstable hemodynamics or recent myocardial infarction may require careful monitoring during the procedure. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Ultrasound contrast agents consist of gas-filled microspheres that increase the backscatter of ultrasound waves, improving the endocardial border definition. * **Contraindications:** Absolute contraindications include known hypersensitivity to the agent and **Right-to-Left shunts** (as bubbles can enter systemic circulation and cause embolic phenomena). * **Safety Profile:** Unlike CT contrast, echo contrast is **not nephrotoxic** and does not contain iodine, making it safe for patients with renal failure.

Question 570: All of the following glucocorticoids lack mineralocorticoid activity, except?

A. Beclomethasone
B. Triamcinolone
C. Prednisolone (Correct Answer)
D. Dexamethasone

Explanation: **Explanation:** The core concept tested here is the **Mineralocorticoid (MC) vs. Glucocorticoid (GC) potency ratio** of various synthetic steroids. While natural cortisol has equal MC and GC activity, synthetic modifications are designed to enhance anti-inflammatory effects while minimizing salt and water retention. **1. Why Prednisolone is the Correct Answer:** Prednisolone is a short-to-intermediate-acting glucocorticoid. Unlike highly selective synthetic steroids, it retains a **significant degree of mineralocorticoid activity** (MC potency of 0.8 compared to its GC potency of 4). Therefore, it can cause sodium retention and potassium loss, making it the only option among the four that does not "lack" MC activity. **2. Why the Other Options are Incorrect:** * **Triamcinolone:** This is an intermediate-acting steroid specifically modified to have **zero mineralocorticoid activity**. It is often used when salt retention must be strictly avoided. * **Dexamethasone:** A long-acting, highly potent glucocorticoid. It has a GC potency of 25–30 but **negligible (zero) mineralocorticoid activity**. * **Beclomethasone:** This is a topically active fluorinated corticosteroid (often used in inhalers). Due to its chemical structure and high topical-to-systemic potency ratio, it lacks significant systemic mineralocorticoid effects. **High-Yield Clinical Pearls for NEET-PG:** * **Highest MC Activity:** Fludrocortisone (used in Addison’s disease). * **Zero MC Activity:** Dexamethasone, Betamethasone, and Triamcinolone. * **Potency Ratio:** Dexamethasone is roughly 5-7 times more potent than Prednisolone in terms of anti-inflammatory (GC) effect. * **Drug of Choice in Pregnancy:** Prednisolone (it is inactivated by placental 11β-HSD2, protecting the fetus), whereas Dexamethasone crosses the placenta (used for fetal lung maturity).

Practice by Chapter

Hypothalamic and Pituitary Hormones

Practice Questions

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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