Endocrine Pharmacology Practice Questions

Q: Which of the following is NOT a side effect of insulin?

Albuminuria. **Explanation:** **Albuminuria** is the correct answer because it is not a side effect of insulin; rather, it is a clinical marker of **Diabetic Nephropathy** (a complication of the disease itself). Insulin therapy is actually used to achieve glycemic control, which helps prevent or slow the progression of albuminuria. **Analysis of Options:** * **A. Edema:** Insulin causes renal sodium reabsorption in the distal tubules. In some patients, initiating insulin therapy leads to "Insulin Edema" due to salt and water retention. * **C. Hypoglycemia:** This is the **most common** and most serious side effect of insulin therapy, occurring due to an overdose, delayed meals, or excessive physical activity. * **D. Lipodystrophy:** This occurs at the site of injection. It can manifest as **Lipoatrophy** (immune-mediated loss of fat, rarer with human insulin) or **Lipohypertrophy** (fat accumulation due to the anabolic effects of insulin, often caused by failing to rotate injection sites). **High-Yield NEET-PG Pearls:** 1. **Weight Gain:** Insulin is an anabolic hormone; weight gain is a very common side effect. 2. **Hypokalemia:** Insulin shifts potassium into cells by activating the Na+/K+ ATPase pump. This is why it is used in the emergency management of hyperkalemia. 3. **Somogyi Effect:** Post-hypoglycemic hyperglycemia caused by a counter-regulatory hormonal surge (epinephrine, glucagon) in response to late-night hypoglycemia. 4. **Injection Sites:** Absorption is fastest in the abdomen, followed by the arms, thighs, and buttocks.

Q: Which of the following is NOT a testosterone inhibitor?

Sildenafil. ### Explanation The correct answer is **D. Sildenafil**. **Mechanism of Action (The "Why"):** Sildenafil is a **Phosphodiesterase-5 (PDE-5) inhibitor**. It works by preventing the degradation of cyclic Guanosine Monophosphate (cGMP) in the corpus cavernosum, leading to smooth muscle relaxation and increased blood flow. It is used to treat erectile dysfunction and pulmonary arterial hypertension. It does **not** interfere with the synthesis, metabolism, or receptor binding of testosterone. **Analysis of Incorrect Options:** * **A. Spironolactone:** A potassium-sparing diuretic that also acts as a weak **androgen receptor antagonist** and inhibits steroidogenesis. It is often used clinically to treat hirsutism in women due to these anti-androgenic effects. * **B. Flutamide:** A potent, non-steroidal **pure androgen receptor antagonist**. It competes with testosterone and dihydrotestosterone (DHT) for binding sites. It is primarily used in the management of prostate cancer. * **C. Finasteride:** A **5-alpha-reductase inhibitor**. It prevents the conversion of testosterone into its more potent metabolite, Dihydrotestosterone (DHT). It is used for Benign Prostatic Hyperplasia (BPH) and male pattern baldness. **High-Yield Clinical Pearls for NEET-PG:** * **Anti-androgen Classifications:** * *Receptor Antagonists:* Flutamide, Bicalutamide, Spironolactone, Cyproterone. * *5-α Reductase Inhibitors:* Finasteride (Type II), Dutasteride (Type I & II). * *GnRH Analogues (Continuous):* Leuprolide, Goserelin (initially cause a "flare," then suppress testosterone). * **Side Effect Note:** Spironolactone can cause **gynecomastia** in men due to its anti-androgenic activity. * **Sildenafil Contraindication:** Never co-administer with **nitrates**, as it can cause life-threatening hypotension.

Q: Which of the following is not a GnRH agonist?

Ganirelix. ### Explanation The correct answer is **Ganirelix**. **1. Understanding the Mechanism:** GnRH (Gonadotropin-Releasing Hormone) modulators are divided into two distinct classes based on their interaction with the GnRH receptor: * **GnRH Agonists:** These drugs initially cause a "flare" (surge in LH/FSH) followed by down-regulation and desensitization of receptors, leading to medical castration. * **GnRH Antagonists:** These drugs provide **immediate** suppression of gonadotropins by competitively blocking the GnRH receptor without any initial flare. **Ganirelix** (along with Cetrorelix and Degarelix) belongs to this class. **2. Analysis of Options:** * **Leuprolide (Option A):** A potent synthetic GnRH agonist used commonly in prostate cancer and endometriosis. * **Nafarelin (Option B):** A GnRH agonist typically administered as a nasal spray for central precocious puberty and endometriosis. * **Buserelin (Option D):** Another GnRH agonist used in the management of hormone-dependent tumors and IVF protocols. **3. NEET-PG High-Yield Pearls:** * **The "Relix" Rule:** Drugs ending in **"-relix"** (Ganirelix, Cetrorelix, Degarelix, Abarelix) are **Antagonists**. * **The "Relin" Rule:** Most drugs ending in **"-relin"** (Goserelin, Nafarelin, Buserelin, Triptorelin) are **Agonists** (Exception: Leuprolide). * **Clinical Use:** GnRH antagonists (Ganirelix) are preferred in IVF protocols to prevent premature LH surges because they act instantly and do not require the 7–10 day desensitization period needed by agonists. * **Side Effects:** Both classes cause symptoms of hypogonadism (hot flashes, decreased bone density). However, only agonists carry the risk of "tumor flare" in prostate cancer.

Q: Which drug, when taken by a patient, necessitates careful monitoring for hypoglycemia?

Chlorpropamide. **Explanation:** **Chlorpropamide** is a first-generation **Sulfonylurea** used in the management of Type 2 Diabetes Mellitus. Its primary mechanism of action involves stimulating insulin release from pancreatic beta cells by closing ATP-sensitive potassium channels. **Why Chlorpropamide causes hypoglycemia:** Among all sulfonylureas, Chlorpropamide has an exceptionally **long half-life (approx. 36 hours)** and is excreted unchanged by the kidneys. This prolonged duration of action significantly increases the risk of severe, prolonged hypoglycemia, especially in elderly patients or those with renal impairment. Therefore, patients on this drug require vigilant monitoring. **Analysis of Incorrect Options:** * **Furosemide (Loop Diuretic):** This drug is more likely to cause **hyperglycemia** (by inhibiting insulin release and causing hypokalemia) and electrolyte imbalances (hypokalemia, hyponatremia). * **Corticosteroids:** These are classic "diabetogenic" drugs. They promote gluconeogenesis and decrease peripheral glucose uptake, leading to **hyperglycemia** (Steroid-induced diabetes). * **Theophylline:** A methylxanthine used in asthma; in toxic doses, it typically causes **hyperglycemia** due to increased catecholamine release. **NEET-PG High-Yield Pearls:** 1. **Disulfiram-like reaction:** Chlorpropamide is notorious for causing flushing when taken with alcohol. 2. **SIADH:** Chlorpropamide can induce the Syndrome of Inappropriate Antidiuretic Hormone secretion, leading to dilutional hyponatremia. 3. **Drug of Choice for Hypoglycemia:** For sulfonylurea-induced hypoglycemia refractory to glucose, **Octreotide** (a somatostatin analogue) is used to suppress further insulin release.

Q: What is Pegvisomant used to treat?

Acromegaly. **Pegvisomant** is a genetically modified analogue of human growth hormone (GH) that acts as a highly selective **Growth Hormone Receptor Antagonist**. 1. **Why Acromegaly is correct:** Acromegaly is caused by excessive secretion of GH, usually due to a pituitary adenoma, leading to elevated Insulin-like Growth Factor-1 (IGF-1) levels [1]. Pegvisomant binds to the GH receptor but prevents the functional dimerization required for signal transduction. By blocking the peripheral action of GH, it effectively lowers serum IGF-1 levels, making it a potent treatment for patients who are resistant to or intolerant of somatostatin analogues (like Octreotide). 2. **Why the other options are incorrect:** * **Dwarfism:** This is caused by GH deficiency. Treatment requires **Somatropin** (recombinant GH) or **Mecasermin** (recombinant IGF-1), not an antagonist. * **Cretinism:** This refers to congenital hypothyroidism. It is treated with **Levothyroxine**. * **Protein Energy Malnutrition (PEM):** While GH levels may be high in PEM due to resistance, Pegvisomant has no therapeutic role here; management focuses on nutritional rehabilitation. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** It is a GH receptor antagonist (blocks the JAK2-STAT5 pathway). * **Monitoring:** Unlike Somatostatin analogues, Pegvisomant **does not shrink the pituitary tumor**. Therefore, serial MRI scans of the pituitary are mandatory. * **Side Effects:** Potential for liver enzyme elevation (monitor LFTs) and lipohypertrophy at the injection site. * **Biochemical Goal:** The primary goal of therapy is the normalization of **serum IGF-1 levels**, not GH levels (GH levels may actually rise during treatment due to loss of negative feedback).

Q: Which drug(s) can cause SIADH?

All of the above. The Syndrome of Inappropriate Antidiuretic Hormone (SIADH) is characterized by the excessive release of ADH (Vasopressin), leading to water retention, dilutional hyponatremia, and concentrated urine [1]. Several drugs can induce this condition by either stimulating the release of ADH from the posterior pituitary or by sensitizing the renal tubules to its effects. **Breakdown of Options:** * **Chlorpropamide (Option A):** This first-generation sulfonylurea is a classic cause of SIADH [1]. It acts by increasing the sensitivity of the V2 receptors in the renal collecting ducts to endogenous ADH and also stimulates ADH release [1]. * **Oxytocin (Option B):** Oxytocin is structurally very similar to ADH (differing by only two amino acids) [2]. When administered in high doses (e.g., for labor induction or postpartum hemorrhage), it exerts a "cross-reactivity" effect on V2 receptors, leading to potent antidiuretic activity and potential water intoxication [2]. * **Cyclophosphamide (Option C):** This alkylating cytotoxic agent can cause SIADH, particularly when administered intravenously. It is often given with aggressive hydration to prevent hemorrhagic cystitis; if SIADH occurs simultaneously, it significantly increases the risk of severe hyponatremia. **Clinical Pearls for NEET-PG:** * **Other High-Yield Drugs causing SIADH:** SSRIs (e.g., Fluoxetine), Carbamazepine [1], Vincristine, and Haloperidol. * **Treatment of Choice:** Fluid restriction is the first-line management [1]. For pharmacological intervention, **Vaptans** (Tolvaptan, Conivaptan) are used as ADH receptor antagonists [1]. * **Demeclocycline:** An older tetracycline used to treat chronic SIADH because it induces a state of nephrogenic diabetes insipidus [1].

Q: What is the drug of choice for thyroid storm?

Propylthiouracil. **Explanation:** **Propylthiouracil (PTU)** is the drug of choice for thyroid storm because of its unique dual mechanism of action. Unlike other antithyroid drugs, PTU not only inhibits the enzyme **thyroid peroxidase** (preventing the synthesis of new thyroid hormones) but also **inhibits the peripheral conversion of T4 to the more potent T3** by blocking the 5’-deiodinase enzyme. In a life-threatening thyroid storm, rapidly reducing the peripheral levels of active T3 is crucial for clinical stabilization. **Why other options are incorrect:** * **Thiocyanates and Perchlorates (Options A & B):** These are ionic inhibitors that block the iodide trap. They are rarely used clinically due to toxicity (e.g., aplastic anemia with perchlorates) and are significantly less effective than thionamides in acute crises. * **Radioactive Iodine (Option D):** RAI is strictly contraindicated in thyroid storm. It causes radiation thyroiditis, which initially leads to the release of stored thyroid hormones into the blood, potentially worsening the storm. It is used for permanent ablation only after the patient is rendered euthyroid. **Clinical Pearls for NEET-PG:** * **Management Sequence:** The standard protocol for thyroid storm is: **PTU** (to stop synthesis/conversion) → **Iodides/Lugol’s Iodine** (to inhibit hormone release via the Wolff-Chaikoff effect, given 1 hour *after* PTU) → **Propranolol** (to control sympathetic overactivity) → **Hydrocortisone** (to prevent adrenal insufficiency and further inhibit T4 to T3 conversion). * **Pregnancy:** PTU is the drug of choice in the **1st trimester** (less teratogenic), while Methimazole is preferred in the 2nd and 3rd trimesters (lower risk of hepatotoxicity).

Question 1

Which of the following is an indication for the use of corticosteroids?

Accepted Answer

Loffler's syndrome

Answer

Psychosis

Answer

Herpes simplex

Answer

Subacute thyroiditis

Question 2

The unique property of Selective Estrogen Receptor Modulators (SERMs) is that they:

Accepted Answer

Act as an agonist in some tissues and an antagonist in other tissues

Answer

Have both estrogenic and progestational agonistic activity

Answer

Inhibit the aromatase enzyme that is required for estrogen synthesis

Answer

Produce an estrogenic effect without binding to estrogen receptors

Question 3

Which of the following is NOT a side effect of insulin?

Accepted Answer

Albuminuria

Answer

Edema

Answer

Hypoglycemia

Answer

Lipodystrophy

Question 4

Which of the following is NOT a testosterone inhibitor?

Accepted Answer

Sildenafil

Answer

Spironolactone

Answer

Flutamide

Answer

Finasteride

Question 5

Which of the following is not a GnRH agonist?

Accepted Answer

Ganirelix

Answer

Leuprolide

Answer

Nafarelin

Answer

Buserelin

Question 6

Which drug, when taken by a patient, necessitates careful monitoring for hypoglycemia?

Accepted Answer

Chlorpropamide

Answer

Furosemide

Answer

Corticosteroids

Answer

Theophylline

Question 7

What is Pegvisomant used to treat?

Accepted Answer

Acromegaly

Answer

Dwarfism

Answer

Cretinism

Answer

Protein energy malnutrition

Question 8

Which drug(s) can cause SIADH?

Accepted Answer

All of the above

Answer

Chlorpropamide

Answer

Oxytocin

Answer

Cyclophosphamide

Question 9

Which Dipeptidyl Peptidase-4 (DPP4) inhibitor requires dose reduction in both liver and kidney failure?

Accepted Answer

Vildagliptin

Answer

Linagliptin

Answer

Sitagliptin

Answer

Saxagliptin

Question 10

What is the drug of choice for thyroid storm?

Accepted Answer

Propylthiouracil

Answer

Thiocayanates

Answer

Perchlorates

Answer

Radioactive iodine

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

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