Endocrinology — MCQs

A 52-year-old woman presents with a 1-year history of upper truncal obesity and moderate depression. Physical examination shows hirsutism and moon facies. A CT scan of the thorax displays a hilar mass. A transbronchial lung biopsy discloses small cell carcinoma. Electron microscopy of this patient's lung tumor will most likely reveal which of the following cytologic features?

Q979Easy

Triple A syndrome includes all of the following except?

Q980Medium

Insulin resistance is seen in all of the following conditions EXCEPT:

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 971: All are true about central hypothyroidism except?

A. Craniopharyngioma
B. Treatment is guided by TSH levels in plasma (Correct Answer)
C. TSH level is not a good marker for diagnosis
D. Before starting treatment, check for adrenal insufficiency

Explanation: **Explanation:** Central hypothyroidism (secondary/tertiary) occurs due to pathology in the pituitary gland or hypothalamus, leading to insufficient TSH production or activity [3]. **1. Why Option B is the Correct Answer (The False Statement):** In central hypothyroidism, the TSH level is unreliable because the pituitary is the source of the pathology. TSH may be low, inappropriately "normal," or even slightly elevated (due to biologically inactive TSH) [2]. Therefore, **treatment is guided by Free T4 (FT4) levels**, aiming for the upper half of the reference range [2]. Using TSH to monitor therapy would lead to under-treatment. **2. Analysis of Other Options:** * **Option A (Craniopharyngioma):** This is the most common tumor causing central hypothyroidism in children and young adults by compressing the hypothalamus or pituitary stalk. * **Option C (TSH not a good marker for diagnosis):** Correct. Diagnosis relies on finding a **low Free T4** in the presence of a TSH that is not appropriately elevated (low or normal). * **Option D (Check for adrenal insufficiency):** Crucial clinical step. Central hypothyroidism often coexists with ACTH deficiency. Starting Levothyroxine before Glucocorticoids can precipitate an **acute adrenal crisis** by increasing the metabolic clearance of the little cortisol remaining [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Rule of Thumb:** In Primary Hypothyroidism, follow TSH. In Central Hypothyroidism, follow Free T4 [2]. * **The "Pituitary-Adrenal" Rule:** Always rule out or treat adrenal insufficiency *before* thyroid replacement in any patient with suspected pituitary disease [2]. * **Common Causes:** Pituitary adenomas (most common in adults), Sheehan syndrome, trauma, and surgery/radiation [1].

Question 972: What is the composition of Lugol's iodine?

A. 10% KI with 5% Iodine (Correct Answer)
B. 5% KI and 15% Iodine
C. 5% Iodine with 20% KI
D. 10% Iodine and 20% KI

Explanation: **Explanation:** **Lugol’s Iodine** (Strong Iodine Solution) is a classic preparation used in clinical endocrinology. Its standard composition is **5% elemental Iodine (I₂)** and **10% Potassium Iodide (KI)** in distilled water. The rationale behind this specific combination is chemical solubility: elemental iodine is poorly soluble in water. The addition of Potassium Iodide (KI) facilitates the formation of triiodide ions ($I_3^-$), which are highly water-soluble, allowing for a stable, concentrated medicinal solution [1]. **Analysis of Options:** * **Option A (Correct):** Matches the standard USP/IP formulation of 5% Iodine and 10% KI. * **Options B, C, and D:** These represent incorrect ratios. While various "dilute" iodine solutions exist, they do not constitute the official "Lugol’s" formula used in medical practice. **Clinical Pearls for NEET-PG:** 1. **Pre-operative Preparation:** Lugol’s iodine is primarily used 7–10 days before a thyroidectomy in Graves' disease [2]. It decreases the vascularity and size of the thyroid gland, making surgery technically easier and safer. 2. **Wolff-Chaikoff Effect:** This is the physiological mechanism where high levels of circulating iodide acutely inhibit the organification of iodine, thereby suppressing the synthesis of T3 and T4. 3. **Thyroid Storm:** It is used as an adjunctive treatment to rapidly block thyroid hormone release. 4. **Contraindication:** It should never be given *before* starting anti-thyroid drugs (like Carbimazole) in a thyroid storm, as the iodine could be used as substrate for more hormone synthesis (Jod-Basedow phenomenon). Always give it at least 1 hour after anti-thyroid medication.

Question 973: All of the following are features of MEN IIa, except?

A. Pituitary tumor (Correct Answer)
B. Pheochromocytoma
C. Medullary carcinoma thyroid
D. Parathyroid hyperplasia

Explanation: **Explanation:** The **Multiple Endocrine Neoplasia (MEN)** syndromes are autosomal dominant conditions caused by germline mutations. This question tests the ability to differentiate between MEN I and MEN IIa. **1. Why Pituitary Tumor is the Correct Answer:** Pituitary tumors are a hallmark of **MEN I (Wermer’s Syndrome)**, not MEN IIa. MEN I is characterized by the "3 Ps": **P**ituitary adenomas, **P**arathyroid hyperplasia, and **P**ancreatic islet cell tumors. Therefore, its presence in a list describing MEN IIa makes it the "except" option. **2. Analysis of Incorrect Options (Features of MEN IIa):** MEN IIa (Sipple Syndrome) is caused by a mutation in the **RET proto-oncogene** and typically presents with: * **Medullary Carcinoma Thyroid (MTC):** Occurs in nearly 100% of cases; often the first manifestation. * **Pheochromocytoma:** Occurs in approximately 50% of patients; often bilateral. * **Parathyroid Hyperplasia:** Seen in about 20-30% of cases, leading to hypercalcemia. **Clinical Pearls for NEET-PG:** * **MEN IIa vs. IIb:** Both feature MTC and Pheochromocytoma. However, MEN IIa includes Parathyroid hyperplasia, while **MEN IIb** features Mucosal neuromas, Marfanoid habitus, and Intestinal ganglioneuromatosis (but *no* parathyroid involvement). * **Screening:** For MEN II syndromes, screening for the **RET mutation** is the gold standard. Prophylactic thyroidectomy is often indicated in mutation carriers. * **Rule of Thumb:** If you see "Pituitary" or "Pancreas," think MEN I. If you see "Medullary Thyroid CA," think MEN II.

Question 974: Which of the following is NOT a feature of Addison's disease?

A. Asthenia
B. Hyperpigmentation
C. Hypertension (Correct Answer)
D. Abdominal pain

Explanation: **Explanation:** Addison’s disease (Primary Adrenocortical Insufficiency) is characterized by the destruction of the adrenal cortex, leading to a deficiency of both **cortisol** and **aldosterone** [1]. **Why Hypertension is the correct answer:** In Addison’s disease, the lack of aldosterone leads to renal wasting of sodium and water, resulting in hypovolemia [4]. Consequently, patients typically present with **hypotension** (specifically postural hypotension), not hypertension. Hypertension would instead be suggestive of mineralocorticoid excess, such as in Cushing’s syndrome or Conn’s syndrome. **Analysis of Incorrect Options:** * **Asthenia (A):** This is the most common presenting symptom. The lack of cortisol leads to profound weakness, fatigue, and malaise [2]. * **Hyperpigmentation (B):** This is a hallmark of *primary* adrenal insufficiency [2]. Low cortisol triggers a compensatory increase in ACTH. Since ACTH and Melanocyte-Stimulating Hormone (MSH) share a common precursor (POMC), excess ACTH stimulates melanocytes, causing darkening of the skin and mucous membranes. * **Abdominal pain (D):** Gastrointestinal symptoms, including nausea, vomiting, and vague abdominal pain, are frequent [2]. In an acute "Addisonian Crisis," this pain can be severe enough to mimic an acute abdomen. **NEET-PG High-Yield Pearls:** * **Electrolyte Triad:** Hyponatremia, Hyperkalemia, and Metabolic Acidosis. * **Diagnosis:** The best initial screening test is the **ACTH Stimulation Test** (Cosyntropin test) [2]. * **Most Common Cause:** Worldwide, Tuberculosis; in developed nations, Autoimmune Adrenalitis [1][3]. * **Key Distinguisher:** Secondary adrenal insufficiency (pituitary cause) does **not** feature hyperpigmentation or significant hyperkalemia (as aldosterone is regulated by the RAAS, not ACTH).

Question 975: What is the most common manifestation of osteoporosis?

A. Compression fracture of the spine (Correct Answer)
B. Asymptomatic, detected incidentally by low serum calcium
C. Bowing of legs
D. Loss of weight

Explanation: **Explanation:** Osteoporosis is a "silent disease" characterized by reduced bone mass and micro-architectural deterioration, leading to increased bone fragility [1]. **Why Option A is Correct:** The most common clinical manifestation of osteoporosis is a **vertebral compression fracture** [2]. These fractures often occur with minimal trauma or even during routine activities like bending or lifting. While many are asymptomatic and discovered on routine imaging, they frequently present as acute back pain, loss of height, or progressive kyphosis (Dowager’s hump). The mid-to-lower thoracic and upper lumbar spine are the most common sites [2]. **Why Other Options are Incorrect:** * **Option B:** Osteoporosis is typically **asymptomatic** until a fracture occurs. However, serum calcium, phosphate, and alkaline phosphatase levels are characteristically **normal** in primary osteoporosis. Low serum calcium suggests other metabolic bone diseases like Osteomalacia [3]. * **Option C:** Bowing of legs is a classic feature of **Rickets** (in children) or **Osteomalacia/Paget’s disease** (in adults), where the bone matrix is soft or poorly mineralized, unlike osteoporosis where the matrix is normal but decreased in quantity [3]. * **Option D:** Loss of weight is not a feature of osteoporosis. However, **loss of height** is a significant clinical sign due to vertebral collapse. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard Diagnosis:** Dual-energy X-ray absorptiometry (DEXA) scan. Osteoporosis is defined as a **T-score ≤ -2.5**. * **Most Common Site of Fracture:** Vertebrae (Compression fracture) [2]. * **Most Common Site of Fracture requiring Hospitalization:** Hip (Femur neck) [2]. * **First-line Treatment:** Bisphosphonates (e.g., Alendronate). * **Screening:** Recommended for all women ≥65 years and men ≥70 years.

Question 976: All are clinical features of pheochromocytoma, except?

A. Increased hematocrit
B. Orthostatic hypotension
C. Low cortisol level (Correct Answer)
D. Impaired glucose tolerance

Explanation: **Explanation:** Pheochromocytoma is a catecholamine-secreting tumor of the adrenal medulla [1]. The clinical features are primarily driven by the excessive release of epinephrine and norepinephrine [2]. **Why "Low cortisol level" is the correct answer:** Pheochromocytoma does not cause low cortisol levels. In fact, chronic stress from catecholamine excess can sometimes lead to **elevated** cortisol levels due to ACTH stimulation. Furthermore, some pheochromocytomas can ectopically secrete ACTH, leading to Cushing’s syndrome. Therefore, low cortisol is not a feature of this condition. **Analysis of incorrect options:** * **Increased hematocrit:** Catecholamines cause a contraction of the plasma volume (due to vasoconstriction). This leads to **relative polycythemia** (spurious erythrocytosis), resulting in an elevated hematocrit. * **Orthostatic hypotension:** Despite being a hypertensive state, patients often experience orthostatic hypotension. This occurs due to a combination of **low plasma volume** and impaired sympathetic reflex mechanisms (downregulation of alpha-receptors) caused by chronic catecholamine exposure. * **Impaired glucose tolerance:** Catecholamines inhibit insulin secretion (via alpha-2 receptors) and stimulate glycogenolysis and gluconeogenesis [2]. This leads to **hyperglycemia** and glucose intolerance in about 50% of patients. **High-Yield Clinical Pearls for NEET-PG:** * **The Rule of 10s:** 10% bilateral, 10% malignant, 10% pediatric, 10% extra-adrenal (Paraganglioma). * **Classic Triad:** Episodic headache, sweating (diaphoresis), and palpitations. * **Diagnosis:** Best initial screening test is **24-hour urinary fractionated metanephrines** or plasma free metanephrines. * **Management:** Always give **Alpha-blockers first** (e.g., Phenoxybenzamine) before Beta-blockers to avoid a hypertensive crisis from unopposed alpha-stimulation.

Question 977: Which lipid abnormality is most commonly associated with diabetes mellitus?

A. High-density lipoprotein (HDL)
B. Triglycerides (Correct Answer)
C. Triglycerides
D. Cholesterol

Explanation: **Explanation:** The characteristic pattern of dyslipidemia in Diabetes Mellitus (often termed **Diabetic Dyslipidemia**) is primarily driven by insulin resistance. In the state of insulin deficiency or resistance, there is increased lipolysis in adipose tissue, leading to an influx of free fatty acids into the liver [1]. This stimulates the overproduction of **Very Low-Density Lipoprotein (VLDL)**, which is rich in **Triglycerides** [3]. Consequently, hypertriglyceridemia is the most common and hallmark lipid abnormality in diabetic patients. **Analysis of Options:** * **Triglycerides (Correct):** Elevated levels occur due to increased hepatic VLDL synthesis and decreased clearance by lipoprotein lipase (LPL), which is insulin-dependent [3]. * **High-density lipoprotein (HDL):** While low HDL is a classic feature of diabetic dyslipidemia, it is a secondary consequence. High triglycerides lead to an exchange where HDL loses protein and gains triglycerides, making it smaller and more easily cleared by the kidneys [2]. Thus, HDL is typically *low*, not high. * **Cholesterol:** Total cholesterol or LDL-C levels may not be significantly higher in diabetics compared to non-diabetics. However, the *quality* of LDL changes; it becomes "Small Dense LDL" (Pattern B), which is highly atherogenic [2]. **NEET-PG High-Yield Pearls:** * **The Lipid Triad of Diabetes:** 1. Hypertriglyceridemia, 2. Low HDL, 3. Small dense LDL particles [2]. * **Target:** In diabetic patients, the primary target of therapy remains **LDL-C** (to reduce CV risk), but the most common baseline abnormality is **Triglycerides**. * **Drug of Choice:** Statins are the first-line treatment for diabetic dyslipidemia to reduce cardiovascular events, regardless of the baseline lipid profile.

Question 978: A 52-year-old woman presents with a 1-year history of upper truncal obesity and moderate depression. Physical examination shows hirsutism and moon facies. A CT scan of the thorax displays a hilar mass. A transbronchial lung biopsy discloses small cell carcinoma. Electron microscopy of this patient's lung tumor will most likely reveal which of the following cytologic features?

A. Councilman bodies
B. Hyperplasia of endoplasmic reticulum
C. Mitochondrial calcification
D. Neuroendocrine granules (Correct Answer)

Explanation: ### Explanation **Clinical Correlation:** The patient presents with classic features of **Cushing Syndrome** (truncal obesity, moon facies, hirsutism, and depression) secondary to **Ectopic ACTH secretion**. The presence of a hilar mass diagnosed as **Small Cell Lung Carcinoma (SCLC)** confirms the source. SCLC is a neuroendocrine tumor known for paraneoplastic syndromes, most commonly SIADH and ectopic ACTH production [1]. **Why the Correct Answer is Right:** Small cell lung carcinoma is derived from **Kulchitsky cells** (enterochromaffin cells), which are part of the APUD (Amine Precursor Uptake and Decarboxylation) system. Under electron microscopy, these neuroendocrine cells characteristically contain **membrane-bound, electron-dense neurosecretory granules**. These granules store the hormones (like ACTH) that lead to the patient's clinical presentation. **Analysis of Incorrect Options:** * **A. Councilman bodies:** These are eosinophilic, apoptotic hepatocytes typically seen in viral hepatitis (especially Yellow Fever). * **B. Hyperplasia of endoplasmic reticulum:** While the Smooth ER is involved in steroid synthesis (seen in the adrenal cortex), it is not a diagnostic feature of the lung tumor itself. * **C. Mitochondrial calcification:** This is a sign of irreversible cell injury/necrosis, not a specific feature of neuroendocrine tumors. **NEET-PG High-Yield Pearls:** * **SCLC Markers:** Positive for Chromogranin A, Synaptophysin, and CD56. * **Paraneoplastic Syndromes of SCLC:** SIADH (most common), Ectopic ACTH (Cushing’s), and Lambert-Eaton Myasthenic Syndrome [2]. * **Azzopardi Effect:** A characteristic histological finding in SCLC where DNA from necrotic tumor cells encrusts vessel walls. * **Treatment:** SCLC is usually disseminated at the time of diagnosis; therefore, chemotherapy is the mainstay of treatment rather than surgery.

Question 979: Triple A syndrome includes all of the following except?

A. Alacrima
B. Addison disease
C. Achlorhydria (Correct Answer)
D. Achalasia

Explanation: **Explanation:** **Triple A Syndrome**, also known as **Allgrove Syndrome**, is a rare autosomal recessive disorder caused by mutations in the **AAAS gene** on chromosome 12q13, which encodes the protein **ALADIN**. **Why Achlorhydria is the correct answer:** Achlorhydria (absence of hydrochloric acid in gastric secretions) is **not** a component of Triple A syndrome. While the syndrome involves the gastrointestinal system via esophageal motility issues, it does not typically affect gastric acid production. **Analysis of the "Triple A" components (Incorrect Options):** 1. **Alacrima (Option A):** Usually the earliest clinical sign. It refers to the absence or deficiency of tear production, often noticed in early infancy. 2. **Achalasia (Option B):** Specifically, achalasia cardia. This involves failure of the lower esophageal sphincter to relax, leading to progressive dysphagia. 3. **Addison Disease (Option C):** Represents primary adrenal insufficiency due to ACTH resistance. Patients typically present with glucocorticoid deficiency (hypoglycemia, weight loss) but often have preserved mineralocorticoid function. **High-Yield Clinical Pearls for NEET-PG:** * **The "4th A":** Triple A syndrome is frequently associated with a fourth "A"—**Autonomic dysfunction** (and other neurological features like peripheral neuropathy or cognitive impairment). * **Inheritance:** Autosomal Recessive. * **Diagnosis:** Schirmer’s test is used to confirm Alacrima; Esophageal manometry/Barium swallow confirms Achalasia. * **Management:** Artificial tears for alacrima, surgical intervention (Heller’s cardiomyotomy) for achalasia, and glucocorticoid replacement for adrenal insufficiency.

Question 980: Insulin resistance is seen in all of the following conditions EXCEPT:

A. Werner's syndrome
B. Addison's disease (Correct Answer)
C. Ataxia telangiectasia
D. Lipodystrophy

Explanation: **Explanation** The core concept behind this question is the relationship between counter-regulatory hormones and insulin sensitivity. **Why Addison’s Disease is the Correct Answer:** Addison’s disease (Primary Adrenal Insufficiency) is characterized by a **deficiency of cortisol** [3]. Cortisol is a potent counter-regulatory hormone that promotes gluconeogenesis and antagonizes the actions of insulin [2]. In its absence, patients experience **increased insulin sensitivity** and are prone to fasting hypoglycemia. Therefore, it is a state of insulin sensitivity, not resistance. **Why the other options are incorrect:** * **Werner’s Syndrome:** This is a progeroid (premature aging) syndrome. It is classically associated with severe insulin resistance and type 2 diabetes mellitus due to metabolic dysfunction associated with DNA repair defects. * **Ataxia Telangiectasia:** This multisystem autosomal recessive disorder involves a defect in the ATM gene. Patients frequently develop significant insulin resistance and progressive glucose intolerance. * **Lipodystrophy:** Whether congenital (e.g., Berardinelli-Seip) or acquired, the lack of functional adipose tissue leads to ectopic fat deposition in the liver and muscles. This triggers severe, often refractory, insulin resistance and acanthosis nigricans [1]. **NEET-PG High-Yield Pearls:** * **Insulin Resistance Syndromes:** Often present with **Acanthosis Nigricans** (hyperpigmented, velvety plaques in intertriginous areas). * **Other conditions with Insulin Resistance:** Polycystic Ovary Syndrome (PCOS), Cushing’s Syndrome, Acromegaly, and Pheochromocytoma. * **Addison’s Disease Triad:** Hyperpigmentation (due to high ACTH/MSH), Hypotension, and Hyponatremia/Hyperkalemia. * **Rule of Thumb:** Excess counter-regulatory hormones (Cortisol, GH, Glucagon, Adrenaline) cause resistance [2]; their deficiency causes sensitivity.

Practice by Chapter

Diabetes Mellitus

Practice Questions

Thyroid Disorders

Practice Questions

Adrenal Gland Disorders

Practice Questions

Pituitary Disorders

Practice Questions

Calcium and Bone Metabolism

Practice Questions

Reproductive Endocrinology

Practice Questions

Lipid Disorders

Practice Questions

Endocrine Hypertension

Practice Questions

Multiple Endocrine Neoplasia

Practice Questions

Obesity and Metabolic Syndrome

Practice Questions

Neuroendocrine Tumors

Practice Questions

Endocrine Emergencies

Practice Questions

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