Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 231: A 32-year-old woman presents with amenorrhea, galactorrhea, and visual field defects, all of several months duration. Magnetic resonance imaging reveals a hypophyseal mass impinging on the optic chiasm. What is the most likely diagnosis?

A. Prolactinoma (Correct Answer)
B. Somatotropic adenoma
C. Corticotropic adenoma
D. Craniopharyngioma

Explanation: **Explanation:** The clinical triad of **amenorrhea, galactorrhea, and visual field defects** in a young woman is the classic presentation of a **Prolactinoma**, the most common secretory tubulointerstitial tumor of the pituitary gland [1]. 1. **Why Prolactinoma is correct:** High levels of prolactin (hyperprolactinemia) inhibit the pulsatile release of GnRH, leading to decreased LH/FSH, which causes **amenorrhea** [2]. Prolactin also directly stimulates milk production (**galactorrhea**). As the tumor grows (macroadenoma, >10mm), it compresses the **optic chiasm** located superior to the sella turcica, resulting in **bitemporal hemianopia** [1], [4]. 2. **Why other options are incorrect:** * **Somatotropic adenoma:** Secretes Growth Hormone (GH), leading to acromegaly (enlarged hands/feet, coarse facial features). While it can cause mass effects, it does not typically cause galactorrhea unless it is a mixed-secretory tumor [3]. * **Corticotropic adenoma:** Secretes ACTH, leading to Cushing’s disease (moon face, truncal obesity, striae). These are usually microadenomas and rarely cause visual field defects [4]. * **Craniopharyngioma:** A suprasellar tumor derived from Rathke’s pouch remnants. While it causes visual defects (often pressure from above) and pituitary dysfunction, it is more common in children and does not typically present with the specific endocrine signature of primary galactorrhea. **High-Yield Clinical Pearls for NEET-PG:** * **First-line treatment:** Unlike other pituitary tumors, the primary treatment for Prolactinoma is **Medical** (Dopamine agonists like **Cabergoline** or Bromocriptine), not surgery [1]. * **Hook Effect:** In extremely high prolactin levels, lab assays may show falsely low results; serial dilution is required for diagnosis. * **Visual Defect:** The classic defect is **Bitemporal Hemianopia** (loss of peripheral vision in both eyes) [4].

Question 232: 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 233: 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 234: 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 235: 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 236: 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 237: 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 238: 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 239: 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 240: 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.

Practice by Chapter

Diabetes Mellitus

Practice Questions

Thyroid Disorders

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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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