Endocrine Pharmacology Practice Questions

Q: If a patient with hyperglycemia is given IV insulin, which of the following can occur?

Hypokalemia. The correct answer is **Hypokalemia (Option A)**. **Mechanism:** Insulin plays a critical role in electrolyte balance by stimulating the **Na⁺/K⁺-ATPase pump** located on the membranes of skeletal muscle and liver cells. When IV insulin is administered, it increases the activity of this pump, leading to an influx of potassium ions from the extracellular fluid (ECF) into the intracellular fluid (ICF) [2]. This shift results in a rapid decrease in serum potassium levels, potentially causing hypokalemia [3]. This effect occurs independently of insulin’s glucose-lowering action. **Analysis of Incorrect Options:** * **B. Hyperkalemia:** This is the opposite of the physiological effect of insulin. However, hyperkalemia is often seen in untreated Diabetic Ketoacidosis (DKA) due to insulin deficiency and acidosis [4]; insulin therapy is used specifically to *reverse* this. * **C & D. Hyponatremia/Hypernatremia:** While insulin affects the Na⁺/K⁺ pump, its primary and most immediate clinical impact is on potassium. Changes in sodium levels in hyperglycemic states are usually secondary to osmotic shifts (dilutional hyponatremia) rather than a direct effect of insulin administration [4]. **NEET-PG High-Yield Pearls:** * **Clinical Application:** Because insulin shifts potassium intracellularly, a combination of **IV Insulin and Dextrose** is a standard emergency treatment for **Hyperkalemia** [3]. * **DKA Management:** In patients with Diabetic Ketoacidosis, serum potassium may appear normal or high, but total body potassium is depleted. Starting insulin can cause a precipitous drop in K⁺; therefore, potassium supplementation is often required even if initial levels are within the normal range [1]. * **Other drugs causing K⁺ shift:** Beta-2 agonists (e.g., Salbutamol) also stimulate the Na⁺/K⁺-ATPase pump and can cause hypokalemia.

Q: What is the mechanism of action of oral hypoglycemic agents?

Enhance glucose uptake by skeletal muscle. **Explanation:** The primary goal of oral hypoglycemic agents (OHAs) is to reduce blood glucose levels in patients with Type 2 Diabetes Mellitus. **Why Option B is Correct:** Several classes of OHAs work by increasing the utilization of glucose in peripheral tissues. Specifically, **Biguanides (Metformin)** and **Thiazolidinediones (Pioglitazone)** act as insulin sensitizers. Metformin activates AMP-activated protein kinase (AMPK), which promotes the translocation of **GLUT-4 transporters** to the cell membranes of skeletal muscle. This directly **enhances glucose uptake** and utilization, thereby lowering plasma glucose levels. **Why the Other Options are Incorrect:** * **Option A:** Inhibiting glucose uptake would lead to hyperglycemia, worsening the diabetic state. * **Option C & D:** Glycogenolysis (breakdown of glycogen to glucose) and Gluconeogenesis (synthesis of glucose from non-carbohydrate sources) are processes that increase blood sugar. OHAs like Metformin actually **inhibit** these hepatic processes to prevent fasting hyperglycemia. **NEET-PG High-Yield Pearls:** * **Metformin** is the first-line drug for T2DM; it does not cause hypoglycemia (euglycemic) or weight gain. * **SGLT-2 Inhibitors (Dapagliflozin):** Act on the proximal tubule to cause glucosuria. * **Sulfonylureas (Glimepiride):** Act by closing ATP-sensitive K+ channels in pancreatic beta cells, leading to insulin secretion. * **DPP-4 Inhibitors (Sitagliptin):** Prevent the breakdown of GLP-1, enhancing glucose-dependent insulin secretion.

Q: Which of the following statements about diazoxide is false?

It can cause severe hypoglycemia.. **Explanation:** **Diazoxide** is a non-diuretic thiazide derivative that acts as a **potassium channel opener**. 1. **Why Option B is the correct answer (False statement):** Diazoxide does not cause hypoglycemia; rather, it causes **hyperglycemia**. By opening ATP-sensitive $K^+$ channels in the pancreatic beta cells, it hyperpolarizes the cell membrane. This prevents the influx of calcium and inhibits the release of insulin. Therefore, it is used to *treat* hypoglycemia, not cause it. 2. **Analysis of other options:** * **Option A (True):** Its primary mechanism of action is the prolonged opening of ATP-dependent $K^+$ channels, which stabilizes the resting membrane potential and prevents depolarization. * **Option C (True):** Because it inhibits insulin secretion, it is a first-line medical management for patients with **insulinoma** (insulin-secreting tumors) or leucine-sensitive hypoglycemia. * **Option D (True):** Diazoxide also opens $K^+$ channels in vascular smooth muscle, leading to vasodilation. While rarely used today due to newer agents, it was historically used as an intravenous bolus for **hypertensive emergencies**. **NEET-PG High-Yield Pearls:** * **Side Effects:** The most characteristic side effect of chronic diazoxide use is **hypertrichosis** (excessive hair growth), similar to Minoxidil. It can also cause salt and water retention. * **Contrast with Sulfonylureas:** While Sulfonylureas *close* $K_{ATP}$ channels to stimulate insulin, Diazoxide *opens* them to inhibit insulin. * **Clinical Use:** Primarily used for persistent hyperinsulinemic hypoglycemia of infancy (PHHI) and inoperable insulinomas.

Q: Which of the following drugs is a Selective Estrogen Receptor Modulator (SERM) useful for the treatment of osteoporosis?

Raloxifene. **Explanation:** **1. Why Raloxifene is Correct:** Raloxifene is a **Selective Estrogen Receptor Modulator (SERM)**. Its clinical utility stems from its unique tissue-specific action: it acts as an **estrogen agonist in the bone**, where it inhibits osteoclast activity and increases bone mineral density, making it effective for preventing and treating postmenopausal osteoporosis. Crucially, it acts as an **estrogen antagonist in the breast and uterus**, thereby reducing the risk of breast cancer and avoiding the risk of endometrial hyperplasia associated with traditional Hormone Replacement Therapy (HRT). **2. Analysis of Incorrect Options:** * **B. Bisphosphonates (e.g., Alendronate):** While these are the first-line drugs for osteoporosis, they are not SERMs. They work by inhibiting the enzyme farnesyl pyrophosphate synthase in osteoclasts, leading to osteoclast apoptosis. * **C. Strontium (Strontium Ranelate):** This is a divalent cation that has a dual action (increasing bone formation and decreasing resorption), but it is not a SERM. * **D. Estradiol:** This is a natural estrogen. While it prevents bone loss, it is not "selective." It stimulates estrogen receptors in the breast and endometrium, increasing the risk of cancer, and is therefore not classified as a SERM. **3. NEET-PG High-Yield Pearls:** * **Raloxifene vs. Tamoxifen:** Tamoxifen is a SERM used for breast cancer; unlike Raloxifene, Tamoxifen is an agonist in the uterus (increasing risk of endometrial cancer). **Raloxifene is an antagonist in the uterus.** * **Adverse Effect:** The most significant side effect of Raloxifene is an increased risk of **Venous Thromboembolism (VTE)** and hot flashes. * **Bazedoxifene:** Another SERM used in combination with conjugated estrogens for osteoporosis and vasomotor symptoms.

Q: What is the drug of choice for the management of hypertension in a patient with pheochromocytoma?

Phenoxybenzamine. Pheochromocytoma is a catecholamine-secreting tumor (epinephrine and norepinephrine) that causes severe hypertension via excessive stimulation of alpha-1 receptors [2]. **Phenoxybenzamine** is the drug of choice for preoperative management because it is an **irreversible, non-competitive, non-selective alpha-blocker** [1, 2]. Its irreversible nature ensures that even if there is a massive surge of catecholamines (e.g., during surgical manipulation of the tumor), the receptors remain blocked, preventing a hypertensive crisis [1, 2]. It is typically started 10–14 days before surgery to allow for blood pressure control and expansion of the contracted intravascular volume [1, 3]. **2. Why the Other Options are Incorrect:** * **Phentolamine:** While it is a non-selective alpha-blocker, it is **reversible and competitive**. * **Labetalol:** Although it has both alpha and beta-blocking properties, the **beta-to-alpha blockade ratio is high (approx. 3:1)**. Using it as monotherapy can lead to "unopposed alpha stimulation," causing a paradoxical rise in blood pressure [1]. * **Esmolol:** This is a short-acting beta-1 selective blocker. Beta-blockers should **never** be used alone in pheochromocytoma; they must only be introduced *after* adequate alpha-blockade is established to prevent hypertensive crisis [1]. **3. NEET-PG Clinical Pearls:** * **The Golden Rule:** Always "Alpha before Beta." Start alpha-blockers first, then add beta-blockers (usually 2-3 days later) to manage tachycardia [1]. * **Rule of 10s:** Pheochromocytoma is 10% bilateral, 10% malignant, 10% pediatric, 10% extra-adrenal (Paraganglioma), and 10% familial. * **Metyrosine:** An adjuvant drug that inhibits *Tyrosine Hydroxylase* (the rate-limiting enzyme in catecholamine synthesis), used in inoperable or malignant cases.

Question 1

If a patient with hyperglycemia is given IV insulin, which of the following can occur?

Accepted Answer

Hypokalemia

Answer

Hyperkalemia

Answer

Hyponatremia

Answer

Hypernatremia

Question 2

A 47-year-old male presented with signs and symptoms of acromegaly. Radiologic studies showed the presence of a large pituitary tumor. Surgical treatment of the tumor was only partially effective in controlling the disease. At this point, which of the following drugs is most likely to be used as pharmacological therapy?

Accepted Answer

Octreotide

Answer

Desmopressin

Answer

Leuprolide

Answer

Somatropin

Question 3

What is the mechanism of action of oral hypoglycemic agents?

Accepted Answer

Enhance glucose uptake by skeletal muscle

Answer

Inhibit glucose uptake by skeletal muscle

Answer

Stimulate glycogenolysis

Answer

Stimulate gluconeogenesis

Question 4

Which of the following statements about diazoxide is false?

Accepted Answer

It can cause severe hypoglycemia.

Answer

It acts by causing prolonged opening of ATP-dependent potassium channels in beta cells.

Answer

It can be used to treat patients with insulinoma.

Answer

It is used as an antihypertensive agent.

Question 5

A pregnant female with thyrotoxicosis is planned for surgery. Before surgery can be done, her gland should be reduced in size and vascularity by administering which of the following?

Accepted Answer

Propylthiouracil

Answer

Iodide ion

Answer

Propranolol

Answer

Radioactive iodine

Question 6

Which of the following drugs is a Selective Estrogen Receptor Modulator (SERM) useful for the treatment of osteoporosis?

Accepted Answer

Raloxifene

Answer

Bisphosphonate

Answer

Strontium

Answer

Estradiol

Question 7

A patient with Addison's disease presented with adrenal crisis. What is the drug of choice?

Accepted Answer

Hydrocortisone

Answer

Betamethasone

Answer

Dexamethasone

Answer

Prednisolone

Question 8

What is the drug of choice for the management of hypertension in a patient with pheochromocytoma?

Accepted Answer

Phenoxybenzamine

Answer

Phentolamine

Answer

Labetalol

Answer

Esmolol

Question 9

Which of the following has more anti-thyroid action?

Accepted Answer

I131

Answer

Sodium iodide

Answer

Carbimazole

Answer

Neomercazole

Question 10

What is the corticosteroid of choice in acute adrenal insufficiency?

Accepted Answer

Hydrocortisone

Answer

Fludrocortisone

Answer

Dexamethasone

Answer

Prednisolone

Endocrine Pharmacology — MCQs

Endocrine Pharmacology — MCQs

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