Endocrine Pharmacology — MCQs

Endocrine Pharmacology Indian Medical PG Practice Questions and MCQs

Question 511: Which of the following is NOT an adverse effect of estrogens?

A. Suppression of libido
B. Fusion of epiphyses
C. Hot flushes (Correct Answer)
D. Gynecomastia in males

Explanation: **Explanation:** The correct answer is **C. Hot flushes**. Estrogens are primarily used to **treat** vasomotor symptoms like hot flushes, not cause them. Hot flushes are a hallmark of estrogen deficiency (e.g., menopause) or the use of anti-estrogens (e.g., Tamoxifen, Clomiphene). Estrogens stabilize the thermoregulatory center in the hypothalamus; therefore, their administration relieves these symptoms. **Analysis of Incorrect Options:** * **A. Suppression of libido:** In males, exogenous estrogen inhibits the secretion of Gonadotropin-Releasing Hormone (GnRH) and Luteinizing Hormone (LH) via negative feedback. This leads to decreased endogenous testosterone production, resulting in decreased libido and erectile dysfunction. * **B. Fusion of epiphyses:** Estrogens play a critical role in bone maturation. High levels of estrogen (either endogenous during puberty or exogenous) promote the closure of epiphyseal plates in long bones, which halts linear growth. * **D. Gynecomastia in males:** Estrogens stimulate the proliferation of glandular breast tissue. In males, an increased estrogen-to-androgen ratio (due to exogenous intake or liver cirrhosis) leads to the development of breast tissue. **High-Yield Clinical Pearls for NEET-PG:** * **Vascular Risk:** Estrogens increase the risk of **Thromboembolism** (DVT/PE) by increasing the synthesis of clotting factors (II, VII, IX, X) and decreasing Antithrombin III. * **Carcinogenicity:** Unopposed estrogen therapy increases the risk of **Endometrial Carcinoma**; hence, Progestins are added in women with an intact uterus. * **Gallstones:** Estrogens increase cholesterol secretion in bile, leading to an increased risk of **cholelithiasis**. * **Migraine:** Estrogens can trigger or worsen migraine headaches due to vascular changes.

Question 512: Treatment of diabetes insipidus includes all of the following EXCEPT:

A. Metformin (Correct Answer)
B. Chlorpropamide
C. Desmopressin
D. Carbamazepine

Explanation: Diabetes Insipidus (DI) is characterized by a deficiency of Antidiuretic Hormone (ADH) or a resistance to its action, leading to polyuria and polydipsia [3]. **1. Why Metformin is the Correct Answer:** **Metformin** is a biguanide used primarily in the management of Type 2 Diabetes Mellitus. Its mechanism involves decreasing hepatic gluconeogenesis and improving insulin sensitivity. It has **no effect on ADH secretion or action** and does not possess any antidiuretic properties. Therefore, it plays no role in the treatment of DI. **2. Analysis of Incorrect Options:** * **Desmopressin (dDAVP):** This is a synthetic V2-selective analogue of ADH and is the **drug of choice** for Central DI [1, 2, 3]. It acts directly on the collecting ducts to increase water reabsorption [2]. * **Chlorpropamide:** A first-generation sulfonylurea that enhances the action of ADH on the renal tubules and may also stimulate ADH release from the posterior pituitary [1]. It is used as an adjuvant in partial central DI [1]. * **Carbamazepine:** Primarily an anticonvulsant, it is known to stimulate the release of ADH and is sometimes used in the management of partial central DI. **Clinical Pearls for NEET-PG:** * **Drug of Choice for Central DI:** Desmopressin (administered intranasally, orally, or parenterally) [1]. * **Drug of Choice for Nephrogenic DI:** Thiazide diuretics (e.g., Hydrochlorothiazide). They paradoxically reduce urine volume by inducing mild hypovolemia, which increases proximal tubule salt and water reabsorption. * **Lithium-induced Nephrogenic DI:** The specific treatment is **Amiloride**, which blocks the ENaC channels through which lithium enters the collecting duct cells. * **Chlorpropamide Side Effect:** It can cause a disulfiram-like reaction with alcohol and is a common cause of SIADH (hyponatremia) in the elderly.

Question 513: What is a known effect of steroids?

A. Increase TSH
B. Increased FSH
C. Prevent de-iodination (Correct Answer)
D. All of the above

Explanation: **Explanation:** **1. Why "Prevent de-iodination" is correct:** Glucocorticoids (steroids) inhibit the enzyme **5'-deiodinase**, which is responsible for the peripheral conversion of the pro-hormone **T4 (Thyroxine)** into its metabolically active form, **T3 (Triiodothyronine)**. By blocking this conversion, steroids effectively lower the circulating levels of active T3. This property is clinically exploited in the management of **Thyroid Storm**, where high doses of steroids (like Dexamethasone or Hydrocortisone) are used to rapidly reduce metabolic activity. **2. Why other options are incorrect:** * **A. Increase TSH:** Steroids actually **suppress** the secretion of Thyroid Stimulating Hormone (TSH) from the anterior pituitary. Chronic steroid use can lead to a state of secondary hypothyroidism or blunted TSH response. * **B. Increased FSH:** Steroids generally exert a negative feedback effect on the hypothalamic-pituitary-gonadal (HPG) axis. High levels of glucocorticoids inhibit the release of GnRH, which leads to a **decrease** in FSH and LH levels, often causing menstrual irregularities or decreased libido. **3. High-Yield Clinical Pearls for NEET-PG:** * **Drugs inhibiting peripheral T4 to T3 conversion:** Remember the mnemonic **"PTU"** (Propylthiouracil, Propranolol, Steroids/Prednisolone, and Amiodarone). * **Steroids in Thyroid Storm:** They serve a dual purpose—inhibiting T4 to T3 conversion and treating potential relative adrenal insufficiency associated with severe thyrotoxicosis. * **Metabolic Effects:** Steroids cause hyperglycemia (gluconeogenesis), proteolysis (muscle wasting), and lipolysis (redistribution of fat).

Question 514: Exenatide is prescribed for which disease?

A. Osteoporosis
B. Diabetes (Correct Answer)
C. Hyperthyroidism
D. Infertility

Explanation: **Exenatide** is a synthetic analog of **Glucagon-Like Peptide-1 (GLP-1)**, which is an incretin hormone. It is primarily used in the management of **Type 2 Diabetes Mellitus**. ### Why Diabetes is Correct: Exenatide acts as a **GLP-1 Receptor Agonist**. It lowers blood glucose through several mechanisms: * **Glucose-dependent insulin secretion:** It stimulates the pancreas to release insulin only when blood sugar levels are high, reducing the risk of hypoglycemia. * **Glucagon suppression:** It inhibits post-prandial glucagon secretion. * **Gastric emptying:** It slows down the rate at which the stomach empties, leading to a slower absorption of glucose. * **Satiety:** It acts on the hypothalamus to increase satiety, often leading to significant **weight loss**. ### Why Other Options are Incorrect: * **A. Osteoporosis:** Treatment typically involves Bisphosphonates, Teriparatide (PTH analog), or Denosumab. Exenatide has no role in bone mineral density management. * **C. Hyperthyroidism:** Managed with antithyroid drugs like Carbimazole, Methimazole, or Propylthiouracil. Notably, GLP-1 agonists are contraindicated in patients with a history of Medullary Thyroid Carcinoma. * **D. Infertility:** Treated with ovulation inductors like Clomiphene citrate or Letrozole. While weight loss from Exenatide might indirectly help PCOS patients, it is not a primary treatment for infertility. ### High-Yield NEET-PG Pearls: * **Source:** Originally derived from the saliva of the **Gila monster** (*Heloderma suspectum*). * **Administration:** Given **subcutaneously**. Liraglutide is another common drug in this class; Semaglutide is available in both oral and injectable forms. * **Major Side Effect:** Gastrointestinal upset (nausea/vomiting) is most common. A rare but serious complication is **Acute Pancreatitis**. * **Benefit:** It is "cardioprotective" and preferred in diabetics with established atherosclerotic cardiovascular disease (ASCVD).

Question 515: An elderly male patient has benign prostatic hyperplasia. Which of the following medications can be used to suppress prostatic growth?

A. Spironolactone
B. Ketoconazole
C. Finasteride (Correct Answer)
D. Flutamide

Explanation: The correct answer is **Finasteride**. **1. Why Finasteride is correct:** Benign Prostatic Hyperplasia (BPH) is driven by **Dihydrotestosterone (DHT)**, a potent androgen synthesized from testosterone by the enzyme **5α-reductase** [1]. Finasteride is a competitive inhibitor of 5α-reductase (specifically Type II). By blocking the conversion of testosterone to DHT, it reduces the size of the prostate gland over time (usually 6–12 months), improves urinary flow, and reduces the need for surgery. **2. Why the other options are incorrect:** * **Spironolactone:** A potassium-sparing diuretic that also acts as an aldosterone and androgen receptor antagonist [1]. While it has anti-androgenic side effects (like gynecomastia), it is not a standard treatment for suppressing prostatic growth in BPH. * **Ketoconazole:** An antifungal that inhibits steroid synthesis (CYP450 enzymes) [1]. While it can lower testosterone levels, its high toxicity and side-effect profile make it unsuitable for BPH management. * **Flutamide:** A pure non-steroidal androgen receptor antagonist. It is primarily used in the treatment of **prostate cancer**, not BPH, as it does not effectively shrink the prostate in benign conditions and carries a risk of hepatotoxicity. **3. NEET-PG High-Yield Pearls:** * **Finasteride vs. Dutasteride:** Finasteride inhibits Type II 5α-reductase; Dutasteride inhibits both Type I and II. * **Clinical Use:** Finasteride is also used for **Male Pattern Baldness** (Androgenetic Alopecia). * **Side Effects:** Decreased libido and erectile dysfunction. * **PSA Levels:** 5α-reductase inhibitors can decrease PSA levels by approximately 50%; this must be accounted for when screening for prostate cancer. * **Immediate Relief:** For rapid symptomatic relief of BPH, **α1-blockers** (e.g., Tamsulosin) [2, 3] are preferred as they relax prostatic smooth muscle without affecting gland size.

Question 516: Which of the following is a GLP-1 analogue used in the management of diabetes mellitus?

A. Exenatide (Correct Answer)
B. Pramalintide
C. Sitagliptin
D. Canagliflozin

Explanation: **Explanation:** **Correct Option: A. Exenatide** Exenatide is a **GLP-1 (Glucagon-Like Peptide-1) receptor agonist**, also known as an **Incretin Mimetic**. GLP-1 is an incretin hormone secreted by the L-cells of the intestine in response to food. It lowers blood glucose by stimulating glucose-dependent insulin secretion, inhibiting glucagon release, and slowing gastric emptying. Exenatide is a synthetic version of exendin-4 (found in Gila monster saliva) and is resistant to degradation by the enzyme DPP-4. **Incorrect Options:** * **B. Pramlintide:** This is a synthetic **Amylin analogue**. It is used as an adjunct to insulin in both Type 1 and Type 2 DM to suppress glucagon and slow gastric emptying. * **C. Sitagliptin:** This is a **DPP-4 inhibitor** (Gliptin). It works by preventing the breakdown of endogenous GLP-1, thereby increasing its half-life. It is an oral drug, unlike GLP-1 analogues which are typically injectable. * **D. Canagliflozin:** This is an **SGLT-2 inhibitor** (Gliflozin). It acts on the proximal convoluted tubule of the kidney to inhibit glucose reabsorption, leading to glucosuria. **High-Yield Clinical Pearls for NEET-PG:** * **Weight Loss:** GLP-1 analogues (e.g., Liraglutide, Semaglutide) are highly effective for weight loss due to increased satiety. * **Cardiovascular Benefit:** Liraglutide and Semaglutide have proven benefits in reducing major adverse cardiovascular events (MACE). * **Side Effects:** The most common side effects are GI-related (nausea/vomiting). A rare but serious association is **Acute Pancreatitis**. * **Contraindication:** They are contraindicated in patients with a personal or family history of Medullary Thyroid Carcinoma (MTC) or MEN 2 syndrome.

Question 517: Which of the following is a long-acting insulin?

A. Lispro
B. Aspart
C. Glulisine
D. Detemir (Correct Answer)

Explanation: ### Explanation **Correct Option: D (Detemir)** Insulin Detemir is a **long-acting (basal) insulin analog**. Its prolonged duration of action (up to 24 hours) is achieved through a unique chemical modification: the addition of a **myristic acid (C14 fatty acid chain)** to the lysine at position B29. This modification allows the insulin molecule to bind to **albumin** in both the subcutaneous tissue and the bloodstream. The slow dissociation from albumin results in a stable, peakless plasma concentration, making it ideal for providing basal insulin coverage. **Incorrect Options:** * **A, B, and C (Lispro, Aspart, Glulisine):** These are **ultra-short-acting (rapid-acting) insulin analogs**. They are designed to dissociate rapidly into monomers after subcutaneous injection, leading to a quick onset (5–15 minutes) and short duration (3–5 hours). They are used specifically for **prandial (mealtime)** glucose control. **High-Yield NEET-PG Pearls:** 1. **Long-acting Analogs:** Include **Glargine** (precipitates at physiological pH), **Detemir** (albumin binding), and **Degludec** (forms multi-hexamers; longest half-life >40 hours). 2. **Peakless Profile:** Unlike NPH (intermediate-acting), long-acting analogs are "peakless," which significantly reduces the risk of **nocturnal hypoglycemia**. 3. **Weight Neutrality:** Detemir is often associated with less weight gain compared to other insulin formulations. 4. **Afrezza:** A rapid-acting **inhaled** insulin; contraindicated in smokers and COPD/Asthma patients. 5. **IV Use:** Only **Regular (soluble) Insulin** is typically used intravenously for managing Diabetic Ketoacidosis (DKA).

Question 518: Which of the following medications used in diabetes management is administered once weekly?

A. Alogliptin
B. Empagliflozin
C. Albiglutide (Correct Answer)
D. Glimepiride

Explanation: **Explanation:** The correct answer is **Albiglutide**. **1. Why Albiglutide is correct:** Albiglutide is a **GLP-1 Receptor Agonist (Incretin mimetic)**. It is a fusion protein consisting of two copies of human GLP-1 linked to human albumin. This structural modification significantly extends its half-life (approximately 5 days), allowing for **once-weekly subcutaneous administration**. Other GLP-1 agonists with once-weekly dosing include **Dulaglutide** and **Semaglutide** (injectable form). **2. Why the other options are incorrect:** * **Alogliptin:** This is a **DPP-4 inhibitor**. All currently available DPP-4 inhibitors (Alogliptin, Sitagliptin, Vildagliptin, Linagliptin) are administered **once or twice daily** orally. * **Empagliflozin:** This is an **SGLT-2 inhibitor**. It is administered **once daily** orally. It is notable for its cardiovascular benefits and osmotic diuretic effect. * **Glimepiride:** This is a **second-generation Sulfonylurea**. It is administered **once daily** orally due to its long duration of action (up to 24 hours). **3. High-Yield Clinical Pearls for NEET-PG:** * **GLP-1 Agonists (The "-tides"):** Associated with weight loss and a low risk of hypoglycemia. A major side effect to remember is **acute pancreatitis**. They are contraindicated in patients with a history of Medullary Thyroid Carcinoma (MTC) or MEN 2. * **Dosing Frequency:** * *Daily:* Liraglutide, Lixisenatide. * *Weekly:* Albiglutide, Dulaglutide, Semaglutide, Exenatide (Extended Release). * **Oral Semaglutide:** It is the first and only oral GLP-1 agonist, but it must be taken **daily**, unlike the weekly injectable form.

Question 519: Which of the following is used to treat Laron's dwarfism?

A. Sermorelin
B. Tesamorelin
C. Mecasermin (Correct Answer)
D. Ganirelix

Explanation: <h3>Explanation</h3>Correct Answer: C. MecaserminMechanism and Rationale:Laron’s dwarfism (Growth Hormone Insensitivity Syndrome) is a rare genetic disorder caused by a mutation in the Growth Hormone (GH) receptor. In these patients, GH levels are normal or high, but the liver cannot produce Insulin-like Growth Factor-1 (IGF-1) in response to GH. Since the defect is at the receptor level, administering exogenous GH is ineffective. Mecasermin, a recombinant human IGF-1 (rhIGF-1), bypasses the defective GH receptor and directly stimulates systemic growth, making it the treatment of choice [1].Analysis of Incorrect Options:<ul><li>A. Sermorelin: A synthetic GHRH analogue used to stimulate the pituitary to release GH. It is ineffective in Laron's dwarfism because the pathology lies downstream of the pituitary.</li><li>B. Tesamorelin: A GHRH analogue specifically used to reduce excess abdominal fat in HIV-infected patients with lipodystrophy.</li><li>C. Ganirelix: A GnRH antagonist used primarily in controlled ovarian hyperstimulation to prevent premature LH surges. It has no role in growth disorders.</li></ul>High-Yield Clinical Pearls for NEET-PG:<ul><li>Diagnosis of Laron's: Characterized by short stature, prominent forehead, depressed nasal bridge, high serum GH, and very low serum IGF-1.</li><li>Mecasermin Side Effect: The most common adverse effect is hypoglycemia (due to IGF-1's insulin-like effects). Patients are advised to consume a snack shortly before or after injection [1].</li><li>Somatropin vs. Mecasermin: Use Somatropin (rhGH) for GH deficiency; use Mecasermin for GH resistance (Laron's).</li></ul>

Question 520: Which of the following is NOT used in the management of thyroid storm?

A. Radioactive iodine (Correct Answer)
B. Glucocorticoids
C. Potassium iodide
D. Propylthiouracil

Explanation: **Explanation:** **Thyroid storm** is a life-threatening medical emergency characterized by extreme hypermetabolism. The management goal is to rapidly inhibit thyroid hormone synthesis, release, and peripheral conversion, while stabilizing systemic symptoms. **Why Radioactive Iodine (RAI) is NOT used:** Radioactive iodine (I-131) is contraindicated in the acute management of thyroid storm. Its mechanism involves the destruction of thyroid parenchyma via beta-radiation, which takes **weeks to months** to achieve an euthyroid state. Crucially, RAI can initially cause a transient release of stored thyroid hormones due to radiation-induced thyroiditis, which would **exacerbate** a thyroid storm and potentially lead to cardiovascular collapse. **Why the other options are used:** * **Propylthiouracil (PTU):** The preferred antithyroid drug in storm because it inhibits both the synthesis of hormones (via TPO inhibition) and the **peripheral conversion of T4 to T3**. * **Potassium Iodide (Lugol’s iodine/SSKI):** Administered to inhibit the *release* of stored hormones (the **Wolff-Chaikoff effect**). *Note: It must be given at least 1 hour after PTU to prevent the iodine from being used as a substrate for new hormone synthesis (Jod-Basedow effect).* * **Glucocorticoids (e.g., Dexamethasone):** These are used to inhibit the peripheral conversion of T4 to T3 and to treat potential relative adrenal insufficiency associated with severe thyrotoxicosis. **High-Yield Clinical Pearls for NEET-PG:** 1. **Beta-blockers:** Propranolol is the drug of choice to control sympathetic overactivity and further inhibit T4 to T3 conversion. 2. **Sequence of Treatment:** 1. Beta-blocker → 2. PTU → 3. Iodine (1 hour later) → 4. Steroids. 3. **Bile acid sequestrants (Cholestyramine):** Can be used as an adjunct to decrease the enterohepatic circulation of thyroid hormones.

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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