Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 231: Dilutional hyponatremia is seen in:

A. Addison's disease (Correct Answer)
B. Diabetes insipidus
C. Diuretic therapy
D. None of the above

Explanation: **Explanation** In **Addison’s disease** (Primary Adrenocortical Insufficiency), dilutional hyponatremia occurs through two primary mechanisms: 1. **Mineralocorticoid Deficiency:** A lack of aldosterone leads to renal sodium wasting and volume depletion [4]. This hypovolemia triggers the non-osmotic release of **Antidiuretic Hormone (ADH)** [3]. 2. **Glucocorticoid Deficiency:** Cortisol normally exerts a negative feedback on ADH. In its absence, ADH levels rise significantly. The resulting excess ADH causes free water retention in the renal collecting ducts via AQP-2 channel insertion [1]. This water retention, combined with the underlying sodium loss, results in **dilutional hyponatremia** [2]. **Analysis of Incorrect Options:** * **B. Diabetes Insipidus:** This condition is characterized by a deficiency of ADH (Central) or resistance to it (Nephrogenic). It leads to excessive water loss (polyuria), resulting in **hypernatremia**, not hyponatremia. * **C. Diuretic Therapy:** While diuretics (especially Thiazides) commonly cause hyponatremia, it is primarily classified as **depletional hyponatremia** due to the direct loss of sodium in the urine, rather than pure water dilution [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Electrolyte Triad in Addison’s:** Hyponatremia, Hyperkalemia, and Metabolic Acidosis (due to lack of aldosterone). * **Cortisol vs. ADH:** Cortisol is a physiological inhibitor of ADH. Therefore, any cause of hypocortisolism (including secondary adrenal insufficiency) can lead to SIADH-like dilutional hyponatremia. * **Diagnosis:** The gold standard is the ACTH stimulation test (Cosyntropin test) [4].

Question 232: In Diabetes Mellitus type II, insulin resistance develops due to which of the following mechanisms?

A. End organ target receptor insensitivity (Correct Answer)
B. Diabetic ketoacidosis
C. Hyperosmolar non-ketotic state
D. Genetic predisposition

Explanation: **Explanation:** **Mechanism of the Correct Answer (A):** Type 2 Diabetes Mellitus (T2DM) is characterized by a dual defect: **insulin resistance** and progressive **beta-cell dysfunction** [3]. Insulin resistance refers to the decreased biological response of peripheral tissues (primarily skeletal muscle, liver, and adipose tissue) to circulating insulin. This "end-organ target receptor insensitivity" occurs due to defects in the insulin signaling pathway, most commonly involving post-receptor signaling abnormalities (e.g., impaired tyrosine kinase activity or phosphorylation of Insulin Receptor Substrates) [2]. Consequently, higher levels of insulin are required to maintain glucose homeostasis [1]. **Analysis of Incorrect Options:** * **B & C (DKA and HHS):** These are **acute metabolic complications** of diabetes, not the underlying cause of insulin resistance. DKA is more common in Type 1 DM (absolute insulin deficiency), while HHS is a hallmark of Type 2 DM (relative insulin deficiency). * **D (Genetic Predisposition):** While T2DM has a stronger genetic component than Type 1 DM, genetics is a **risk factor** or a "predisposing cause," not the physiological mechanism of resistance itself. The question asks for the specific mechanism by which resistance develops. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard for measuring insulin resistance:** Hyperinsulinemic-euglycemic clamp (rarely used clinically). * **First sign of T2DM:** Post-prandial hyperglycemia. * **Key Mediator:** Free Fatty Acids (FFAs) play a crucial role in inducing insulin resistance via the "Randle Cycle" and lipotoxicity [3]. * **Clinical Marker:** Acanthosis Nigricans is a classic cutaneous marker of underlying insulin resistance.

Question 233: A diabetic patient in the waiting room develops giddiness, sweating, and confusion. What is the most likely condition?

A. Hypertension
B. Diabetic ketoacidosis
C. Hypoglycemia (Correct Answer)
D. Non-ketotic hyperosmolar syndrome

Explanation: **Explanation:** The clinical presentation of **giddiness, sweating, and confusion** in a diabetic patient is a classic triad of **Hypoglycemia**. This occurs when blood glucose levels fall below 70 mg/dL [1]. The symptoms are divided into two categories: 1. **Autonomic (Neurogenic):** Sweating, palpitations, tremors, and anxiety (due to catecholamine release) [3]. 2. **Neuroglycopenic:** Confusion, giddiness, behavioral changes, and seizures (due to glucose deprivation in the brain) [4]. **Why other options are incorrect:** * **Diabetic Ketoacidosis (DKA):** Typically presents with hyperglycemia, dehydration, Kussmaul breathing (deep, rapid respirations), and an acetone (fruity) breath odor [2]. It develops over hours to days, not suddenly in a waiting room. * **Non-ketotic Hyperosmolar Syndrome (HHS):** Characterized by extreme hyperglycemia (>600 mg/dL) and profound dehydration, usually in Type 2 diabetics [1]. It lacks the acute autonomic symptoms like sweating. * **Hypertension:** While it can cause headaches or dizziness, it does not typically cause acute confusion and profuse sweating unless in a hypertensive emergency, which is less common than hypoglycemia in a treated diabetic. **High-Yield NEET-PG Pearls:** * **Whipple’s Triad:** 1. Symptoms of hypoglycemia, 2. Low plasma glucose, 3. Relief of symptoms after glucose administration. * **Beta-blockers** can mask hypoglycemic symptoms (except sweating), making it dangerous for diabetic patients. * **Management:** If conscious, give 15g of rapid-acting carbohydrates (Rule of 15). If unconscious, IV 25% or 50% Dextrose is the treatment of choice.

Question 234: Diabetic ketoacidosis (DKA) mimics acute pancreatitis in all the following findings except?

A. Elevated amylase
B. Elevated lipase (Correct Answer)
C. Abdominal pain
D. Hyperglycemia

Explanation: Diabetic Ketoacidosis (DKA) and Acute Pancreatitis (AP) frequently present with overlapping clinical and biochemical features, making the differentiation challenging. However, **Serum Lipase** is the key biochemical marker that distinguishes the two. **1. Why "Elevated Lipase" is the correct answer:** In DKA, **Serum Amylase** is frequently elevated (up to 80% of cases) due to non-pancreatic sources like the salivary glands or decreased renal clearance. Conversely, **Serum Lipase** is much more specific to the pancreas. While minor elevations of lipase can occur in DKA, a significant rise (usually >3 times the upper limit of normal) is highly specific for Acute Pancreatitis. Therefore, DKA mimics the amylase elevation but typically does **not** mimic the significant lipase elevation seen in pancreatitis. **2. Why other options are incorrect:** * **Elevated Amylase:** As noted, this is a common finding in DKA (non-specific elevation), thus DKA "mimics" pancreatitis in this regard. * **Abdominal Pain:** Severe abdominal pain and guarding are classic symptoms of DKA (likely due to delayed gastric emptying and metabolic acidosis), mimicking an "acute abdomen" or pancreatitis [1]. * **Hyperglycemia:** While hyperglycemia is the hallmark of DKA, it is also frequently seen in Acute Pancreatitis due to stress-induced glucagon release and transient islet cell dysfunction [2]. **Clinical Pearls for NEET-PG:** * **The "Rule of 3":** In a patient with DKA, only suspect co-existing Acute Pancreatitis if the **Lipase is >3x normal** or if abdominal pain persists after the metabolic acidosis is corrected. * **CT Scan:** The gold standard for diagnosing pancreatitis when biochemical markers are ambiguous in DKA. * **Hypertriglyceridemia:** Severe DKA can cause massive elevation of triglycerides, which itself is a known trigger for Acute Pancreatitis.

Question 235: All of the following are features of hyperthyroidism except?

A. Rise in BMR
B. Delayed deep tendon reflexes (Correct Answer)
C. Weight loss
D. Moist skin

Explanation: Hyperthyroidism is characterized by a hypermetabolic state due to an excess of circulating thyroid hormones ($T_3$ and $T_4$). These hormones increase the activity of the $Na^+/K^+$ ATPase pump and enhance sympathetic nervous system sensitivity. **1. Why "Delayed deep tendon reflexes" is the correct answer:** Delayed relaxation of deep tendon reflexes (specifically the Achilles reflex), also known as **Woltman’s sign**, is a classic hallmark of **hypothyroidism**, not hyperthyroidism. In hyperthyroidism, the reflexes are typically **brisk or hyperreflexic** due to increased neuromuscular excitability. **2. Analysis of incorrect options:** * **Rise in BMR:** Thyroid hormones directly increase the Basal Metabolic Rate (BMR) by increasing oxygen consumption in most tissues [1]. * **Weight loss:** Despite an increased appetite (polyphagia), the significant rise in BMR leads to a negative energy balance and subsequent weight loss [1]. * **Moist skin:** Increased metabolism generates excess heat (heat intolerance) [1]. To dissipate this heat, cutaneous vasodilation and activation of sweat glands occur, leading to skin that is characteristically warm and moist [3, 4]. **Clinical Pearls for NEET-PG:** * **Apathetic Hyperthyroidism:** Seen in the elderly; presents with depression and lethargy rather than typical hyperactivity. * **Pretibial Myxedema:** A specific dermopathy associated with Graves' disease (not seen in other causes of hyperthyroidism) [3]. * **Thyroid Storm:** A life-threatening exacerbation of hyperthyroidism characterized by fever, tachycardia, and altered mental status. * **Reflexes:** Remember, **Brisk = Hyper**thyroidism; **Hung (Delayed) = Hypo**thyroidism.

Question 236: For which of the following dyslipidemias is hyperchylomicronemia the most characteristic finding?

A. Palmar plane xanthomas
B. Triglycerides > 1000 mg/dL (Correct Answer)
C. Subcutaneous extensor tendon xanthomas
D. Low serum cholesterol

Explanation: **Explanation:** Hyperchylomicronemia (Fredrickson Type I or V hyperlipoproteinemia) is characterized by a massive accumulation of chylomicrons in the plasma, usually due to a deficiency in **lipoprotein lipase (LPL)** or its cofactor **Apo C-II** [1]. **1. Why Option B is Correct:** Chylomicrons are the primary carriers of dietary (exogenous) triglycerides [2]. Because chylomicrons are approximately 90% triglycerides by weight, their massive accumulation leads to extreme hypertriglyceridemia, typically exceeding **1000 mg/dL**. At these levels, the plasma takes on a "milky" appearance, and patients are at a high risk for **acute pancreatitis**. **2. Why the Other Options are Incorrect:** * **Option A (Palmar plane xanthomas):** These are pathognomonic for **Type III Hyperlipoproteinemia** (Dysbetalipoproteinemia), caused by a defect in Apo E, leading to the accumulation of IDL and chylomicron remnants [1]. * **Option C (Subcutaneous extensor tendon xanthomas):** These are classic findings in **Familial Hypercholesterolemia (Type IIa)**, where LDL levels are severely elevated [1]. * **Option D (Low serum cholesterol):** In hyperchylomicronemia, total cholesterol is usually **elevated** (though not as severely as triglycerides) because chylomicrons contain a small percentage of cholesterol. **Clinical Pearls for NEET-PG:** * **Refrigeration Test:** In Type I hyperlipidemia, leaving the serum overnight at 4°C results in a **creamy layer on top** with a clear infranatant. * **Clinical Triad:** Eruptive xanthomas, hepatosplenomegaly, and Lipemia Retinalis. * **Management:** The primary treatment is a **very low-fat diet** (<15% of total calories); conventional fibrates are often less effective in Type I compared to other hypertriglyceridemias.

Question 237: A 55-year-old obese woman presents with frequent vaginal yeast infections in the past 2 months, recent weight loss despite a large appetite, and nocturia. She has a history of hypertension treated with ramipril. What is the most likely diagnosis?

A. Diabetes mellitus (Correct Answer)
B. Diabetes insipidus
C. Vaginitis and cystitis
D. Myxedema

Explanation: **Explanation:** The clinical presentation is classic for **Type 2 Diabetes Mellitus (T2DM)**. The patient exhibits the hallmark "3 Ps": polyphagia (large appetite), polyuria (nocturia), and weight loss [1]. In T2DM, insulin resistance or deficiency leads to hyperglycemia; once blood glucose exceeds the renal threshold (~180 mg/dL), glucose is excreted in the urine (glycosuria), causing osmotic diuresis and nocturia [1], [4]. The weight loss despite polyphagia occurs because the body cannot utilize glucose for energy and begins breaking down fat and muscle [1], [4]. Furthermore, hyperglycemia creates an environment conducive to fungal overgrowth, explaining the recurrent **vaginal candidiasis** [3]. **Analysis of Incorrect Options:** * **B. Diabetes Insipidus:** While it causes polyuria and nocturia, it is due to ADH deficiency or resistance. It does not present with weight loss, polyphagia, or yeast infections. * **C. Vaginitis and Cystitis:** These are localized infections. While they explain the yeast infections and urinary frequency, they do not account for systemic symptoms like weight loss and polyphagia. * **D. Myxedema (Hypothyroidism):** This typically presents with weight gain, constipation, and cold intolerance, which contradicts this patient’s weight loss and increased appetite. **NEET-PG High-Yield Pearls:** * **Screening:** The ADA recommends screening all adults with BMI ≥25 kg/m² who have additional risk factors (e.g., hypertension). * **Diagnostic Criteria:** Fasting Plasma Glucose ≥126 mg/dL, 2-hour OGTT ≥200 mg/dL, or HbA1c ≥6.5% [2]. * **Clinical Clue:** Recurrent vulvovaginal candidiasis is often the first clinical sign of undiagnosed T2DM in women [3].

Question 238: Primary hyperparathyroidism is suggested by all of the following, except:

A. Increased serum calcium
B. Low urinary calcium (Correct Answer)
C. Increased PTH
D. Increased C-AMP

Explanation: In **Primary Hyperparathyroidism (PHPT)**, the fundamental pathology is the autonomous overproduction of Parathyroid Hormone (PTH), usually due to a solitary adenoma [2]. ### Why "Low urinary calcium" is the correct answer: In PHPT, the hallmark is **Hypercalciuria** (increased urinary calcium), not low urinary calcium. While PTH increases calcium reabsorption in the distal renal tubules [1], the massive increase in filtered calcium load (due to high serum levels) eventually overwhelms this reabsorptive capacity. This leads to a net increase in urinary calcium excretion. *Note:* Low urinary calcium (<100 mg/24h) is actually a diagnostic feature of **Familial Hypocalciuric Hypercalcemia (FHH)**, which is the primary differential diagnosis for PHPT [1][3]. ### Explanation of other options: * **A. Increased serum calcium:** PTH stimulates osteoclastic bone resorption and increases renal calcium reabsorption, leading to hypercalcemia [1][2]. * **C. Increased PTH:** PHPT is characterized by inappropriately high or "normal" PTH levels in the presence of high calcium [1][3]. * **D. Increased C-AMP:** PTH acts via G-protein coupled receptors [1]. When PTH binds to its receptor in the kidney, it activates adenylate cyclase, increasing **urinary cyclic AMP (UcAMP)**. This is a classic biochemical marker of PTH activity. ### NEET-PG High-Yield Pearls: * **Most common cause:** Solitary Adenoma (85%). * **Classic Triad:** "Stones (renal calculi), Bones (osteitis fibrosa cystica), and Groans (abdominal pain/constipation)" [3][4]. * **Biochemical Profile:** ↑ Serum Ca²⁺, ↓ Serum Phosphate, ↑ PTH, ↑ Alkaline Phosphatase, and ↑ Urinary cAMP. * **Differential:** To distinguish PHPT from FHH, use the **Calcium/Creatinine Clearance Ratio**. A ratio <0.01 suggests FHH; >0.02 suggests PHPT.

Question 239: All of the following are symptoms of VIPomas except?

A. Watery Diarrhea
B. Hypokalemia
C. Flushing
D. Thromboembolism (Correct Answer)

Explanation: **Explanation:** VIPoma (Vasoactive Intestinal Peptide-secreting tumor), also known as **Verner-Morrison syndrome** or **WDHA syndrome**, is a rare neuroendocrine tumor usually located in the pancreas. [1] **1. Why Thromboembolism is the Correct Answer:** Thromboembolism is **not** a characteristic feature of VIPomas. While thromboembolic events (like Trousseau’s sign) are classically associated with pancreatic adenocarcinoma (non-endocrine), they are not part of the clinical triad of VIPoma. VIPomas primarily affect fluid and electrolyte balance due to the systemic effects of Vasoactive Intestinal Peptide. **2. Analysis of Incorrect Options:** * **Watery Diarrhea:** This is the hallmark symptom. VIP causes massive intestinal secretion of water and electrolytes, leading to "pancreatic cholera" (painless, tea-colored, secretory diarrhea exceeding 700–1000 mL/day). * **Hypokalemia:** The profuse diarrhea leads to significant fecal loss of potassium, resulting in muscle weakness and cardiac arrhythmias. * **Flushing:** VIP has potent vasodilatory properties. Approximately 20% of patients experience episodic cutaneous flushing, similar to carcinoid syndrome. [1] **3. Clinical Pearls for NEET-PG:** * **WDHA Syndrome mnemonic:** **W**atery **D**iarrhea, **H**ypokalemia, **A**chlorhydria (VIP inhibits gastric acid secretion). * **Diagnosis:** Elevated fasting plasma VIP levels (>200 pg/mL). * **Localization:** Most are found in the **tail of the pancreas**. In children, they are often associated with neuroblastomas or ganglioneuromas. * **Treatment:** Initial stabilization requires aggressive fluid resuscitation and **Octreotide** (somatostatin analog) to control diarrhea before surgical resection.

Question 240: Which of the following is the LEAST likely symptom of hyperthyroidism in a 77-year-old man?

A. Atrial fibrillation
B. Confusion
C. Tremor (Correct Answer)
D. Weakness

Explanation: This question tests your knowledge of **Apathetic Hyperthyroidism**, a distinct clinical presentation of thyrotoxicosis seen in the elderly. ### **Explanation** In younger patients, hyperthyroidism typically presents with hyperadrenergic symptoms like tachycardia, anxiety, and **tremors**. However, in the elderly (typically >70 years), these classic "hyperkinetic" features are often absent [1]. This phenomenon is known as **Apathetic Hyperthyroidism**. **Tremor (Option C)** is the least likely symptom because elderly patients often lack the typical sympathetic overactivity seen in younger individuals. Instead of being "hyper," they appear "apathetic" or depressed. ### **Analysis of Other Options** * **Atrial Fibrillation (Option A):** This is the most common cardiovascular manifestation of hyperthyroidism in the elderly [1]. New-onset AFib in an older patient should always prompt a TSH check [2]. * **Confusion (Option B):** Cognitive impairment, lethargy, or "pseudodementia" are hallmark features of apathetic hyperthyroidism, contrasting with the irritability seen in younger patients [1]. * **Weakness (Option D):** Proximal muscle weakness (thyroid myopathy) and significant weight loss are very common in this age group, often leading to a misdiagnosis of occult malignancy [1]. ### **NEET-PG High-Yield Pearls** * **Apathetic Hyperthyroidism:** Characterized by "the triad of the elderly"—**Depression/Apathy, Weight loss, and Atrial Fibrillation.** * **Cardiac focus:** While younger patients get sinus tachycardia, elderly patients are more prone to **Atrial Fibrillation** and **Heart Failure** due to decreased cardiac reserve [1]. * **Diagnosis:** TSH remains the best screening tool. Even if clinical signs are subtle (no goiter, no exophthalmos), a suppressed TSH is diagnostic [2]. * **Clinical Pearl:** In an elderly patient presenting with unexplained weight loss and new-onset AFib, always rule out hyperthyroidism before assuming it is malignancy or primary heart disease [2].

Practice by Chapter

Diabetes Mellitus

Practice Questions

Thyroid Disorders

Practice Questions

Adrenal Gland Disorders

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Pituitary Disorders

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Calcium and Bone Metabolism

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Reproductive Endocrinology

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Lipid Disorders

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Endocrine Hypertension

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Multiple Endocrine Neoplasia

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Obesity and Metabolic Syndrome

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Neuroendocrine Tumors

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Endocrine Emergencies

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