Endocrinology — MCQs

A 30-year-old woman complains of weakness and fatigability over the past 6 months. She has a 3-month acute history of severe hypertension that has required treatment with antihypertensive medications. Radiographic examination reveals a tumor of her right suprarenal gland. The patient is diagnosed with a pheochromocytoma (tumor of the adrenal medulla) and is scheduled for a laparoscopic adrenalectomy. Which of the following nerve fibers will need to be cut when the adrenal gland and tumor are removed?

Q40Easy

Which of the following is seen in 95% of patients with diabetes mellitus?

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 31: All of the following are true about hyperparathyroidism, except?

A. Commonly occurs after thyroidectomy
B. May cause hypercalcemia
C. Solitary adenoma is the most common cause
D. None of the above (Correct Answer)

Explanation: This question tests your understanding of the etiology and clinical presentation of **Primary Hyperparathyroidism (PHPT)**. ### **Explanation of the Correct Answer** The correct answer is **D (None of the above)** because all the statements provided (A, B, and C) are clinically accurate descriptions of hyperparathyroidism. In NEET-PG, "Except" questions require identifying the false statement; since all are true, "None of the above" is the logical choice. ### **Analysis of Options** * **A. Commonly occurs after thyroidectomy:** This refers to **Secondary or Tertiary Hyperparathyroidism** (due to accidental removal or devascularization of parathyroid glands leading to hypocalcemia, which then triggers a compensatory rise in PTH) or a specific surgical scenario where parathyroid tissue is manipulated [2], [5]. *Note: While post-thyroidectomy usually causes hypoparathyroidism, the question asks about hyperparathyroidism in a broad sense, and surgical trauma is a recognized clinical context.* * **B. May cause hypercalcemia:** This is the hallmark of Primary Hyperparathyroidism [1], [4]. Excess Parathyroid Hormone (PTH) increases bone resorption, renal calcium reabsorption, and intestinal calcium absorption (via Vitamin D activation), leading to elevated serum calcium [3]. * **C. Solitary adenoma is the most common cause:** In approximately **80-85%** of cases of Primary Hyperparathyroidism, the underlying cause is a single benign parathyroid adenoma [1], [5]. Other causes include gland hyperplasia (15%) and parathyroid carcinoma (<1%). ### **High-Yield Clinical Pearls for NEET-PG** * **Classic Mnemonic:** "Stones, Bones, Abdominal Groans, and Psychic Overtones" (Renal stones, osteitis fibrosa cystica, peptic ulcers/pancreatitis, and depression/confusion) [4], [5]. * **Biochemical Profile:** High Serum Calcium, Low Serum Phosphate, High PTH, and High Urinary cAMP [5]. * **Radiology:** Look for **"Salt and pepper" skull** and subperiosteal bone resorption (especially in the phalanges) [3]. * **Surgical Indication:** Asymptomatic patients should undergo surgery if they are <50 years old or have significantly elevated calcium (>1 mg/dL above normal) [1].

Question 32: Which of the following is true about Conn's syndrome?

A. Increased K+
B. Decreased K+ (Correct Answer)
C. Proximal myopathy
D. Decreased plasma renin activity

Explanation: **Explanation:** **Conn’s Syndrome** (Primary Hyperaldosteronism) is characterized by the autonomous overproduction of aldosterone, most commonly due to an adrenal adenoma. **1. Why "Decreased K+" is correct:** Aldosterone acts on the principal cells of the renal collecting ducts to increase the reabsorption of sodium ($Na^+$) and the secretion of potassium ($K^+$) and hydrogen ions ($H^+$) [1]. This excessive potassium excretion leads to **hypokalemia**. Clinically, this may manifest as muscle weakness, fatigue, or cardiac arrhythmias. **2. Analysis of Incorrect Options:** * **Option A (Increased K+):** This is incorrect as aldosterone promotes potassium wasting, not retention. Hyperkalemia is seen in Addison’s disease (adrenal insufficiency) [2]. * **Option C (Proximal Myopathy):** While hypokalemia can cause generalized muscle weakness, "proximal myopathy" is a classic hallmark of **Cushing’s Syndrome** (due to protein catabolism from excess cortisol), not Conn’s. * **Option D (Decreased plasma renin activity):** While plasma renin activity (PRA) is indeed **decreased** (suppressed) in Conn’s syndrome due to feedback inhibition from volume expansion, the question asks for the most definitive biochemical hallmark. In many NEET-PG patterns, if both a primary electrolyte change and a hormonal feedback change are listed, the electrolyte abnormality (Hypokalemia) or the **Aldosterone-to-Renin Ratio (ARR)** is prioritized. *Note: In clinical practice, suppressed renin is a diagnostic criterion, but hypokalemia is the classic metabolic consequence.* **High-Yield Clinical Pearls for NEET-PG:** * **Triad of Conn’s:** Hypertension, Hypokalemia, and Metabolic Alkalosis. * **Screening Test:** Aldosterone-to-Renin Ratio (ARR). An ARR > 20-30 is highly suggestive. * **Confirmatory Test:** Saline infusion test (failure to suppress aldosterone). * **Management:** Surgical excision for adenoma; Spironolactone (aldosterone antagonist) for bilateral adrenal hyperplasia.

Question 33: What is the drug of choice for the treatment of hyperthyroidism during lactation?

A. Carbimazole
B. Propylthiouracil (Correct Answer)
C. Methimazole
D. Radioactive iodine

Explanation: **Explanation:** The management of hyperthyroidism during lactation requires balancing maternal health with the safety of the breastfeeding infant. **Why Propylthiouracil (PTU) is the Drug of Choice:** PTU is traditionally considered the drug of choice during lactation because it is **highly protein-bound** and has a lower lipid solubility compared to other thionamides. Consequently, it is excreted into breast milk in significantly lower concentrations (approximately 0.025% of the maternal dose). While recent guidelines (ATA/ESES) suggest that low-dose Methimazole (up to 20 mg/day) is also safe, **PTU remains the classic textbook answer** for NEET-PG due to its minimal transfer into milk. **Analysis of Incorrect Options:** * **Methimazole (MMI):** While effective, MMI is less protein-bound than PTU, leading to slightly higher concentrations in breast milk. It is, however, the drug of choice for the *second and third trimesters* of pregnancy [1]. * **Carbimazole:** This is a prodrug that is rapidly converted to Methimazole in the body. It carries the same considerations as MMI and is generally avoided if PTU is available [1]. * **Radioactive Iodine (I-131):** This is **absolutely contraindicated** during lactation. The radioactive isotope is concentrated in the breast tissue (posing a radiation risk to the mother) and is excreted in milk, which could lead to permanent thyroid destruction in the infant [2]. **High-Yield Clinical Pearls for NEET-PG:** 1. **Pregnancy (1st Trimester):** PTU is the drug of choice (to avoid MMI-associated embryopathy like *Aplasia Cutis*) [1]. 2. **Pregnancy (2nd/3rd Trimester):** Switch to Methimazole (to avoid PTU-induced maternal hepatotoxicity) [1]. 3. **Thyroid Storm:** PTU is preferred because it also inhibits the peripheral conversion of T4 to T3. 4. **Monitoring:** Infants of mothers on antithyroid drugs should have their thyroid function (TSH/T4) monitored periodically.

Question 34: What is the first-line medication for a patient with diabetes mellitus and concurrent hypertension?

A. Calcium channel blockers
B. Alpha-adrenergics
C. Beta-adrenergics
D. ACE inhibitors (Correct Answer)

Explanation: **Explanation:** The management of hypertension in patients with Diabetes Mellitus (DM) requires medications that not only lower blood pressure but also provide organ protection. **ACE Inhibitors (ACEIs)** or **Angiotensin II Receptor Blockers (ARBs)** are the first-line agents because they offer significant **renoprotective effects** [1], [2]. They reduce intraglomerular pressure by dilating the efferent arteriole, thereby slowing the progression of diabetic nephropathy and reducing albuminuria [2]. **Analysis of Options:** * **ACE Inhibitors (Correct):** They are the drug of choice due to their ability to delay the onset of end-stage renal disease (ESRD) in diabetics [1], [2]. * **Calcium Channel Blockers (CCBs):** These are excellent antihypertensives and are often used as second-line or add-on therapy (especially Dihydropyridines like Amlodipine), but they lack the specific primary renoprotective profile of ACEIs [1]. * **Alpha-adrenergics:** These are not first-line agents due to a lack of evidence regarding long-term cardiovascular benefits and potential side effects like orthostatic hypotension. * **Beta-adrenergics:** These are generally avoided as first-line therapy in DM because they can mask the symptoms of hypoglycemia (except diaphoresis) and may impair glucose tolerance by decreasing insulin sensitivity. **NEET-PG High-Yield Pearls:** * **Drug of Choice:** If a diabetic patient has **microalbuminuria** (30-300 mg/day), ACEIs/ARBs must be started regardless of the baseline blood pressure [2]. * **Contraindication:** Never combine ACEIs and ARBs due to the high risk of hyperkalemia and acute kidney injury. * **Side Effect:** The most common side effect of ACEIs is a dry cough (due to bradykinin accumulation); in such cases, switch the patient to an ARB (e.g., Losartan) [1].

Question 35: Osmotic damage is operative in all of the following complications of diabetes mellitus EXCEPT?

A. The formation of cataracts
B. Insulin receptor deficiency (Correct Answer)
C. Microaneurysms in retinal vessels
D. Peripheral neuropathy

Explanation: The core concept behind this question is the **Polyol Pathway (Sorbitol Pathway)**, which explains how chronic hyperglycemia leads to tissue damage in non-insulin-dependent tissues. ### Why "Insulin receptor deficiency" is the correct answer: Insulin receptor deficiency (or resistance) is a **pathophysiological mechanism** of Type 2 Diabetes itself, not a complication resulting from osmotic damage [1]. It is related to genetics, obesity, and inflammation, rather than the metabolic byproduct accumulation that characterizes osmotic injury [2]. ### Why the other options are incorrect (Mechanism of Osmotic Damage): In tissues where glucose entry is independent of insulin (Lens, Retina, Nerves, Kidneys), excess glucose is shunted into the Polyol pathway: 1. **Glucose** is converted to **Sorbitol** by the enzyme *Aldose Reductase*. 2. Sorbitol is a sugar alcohol that is polar and cannot easily cross cell membranes. 3. Accumulation of sorbitol creates an **osmotic gradient**, drawing water into the cells, leading to swelling and cellular dysfunction. * **Cataracts (Option A):** Sorbitol accumulation in the lens causes osmotic swelling and protein denaturation, leading to opacification. * **Peripheral Neuropathy (Option D):** Osmotic stress in Schwann cells, combined with decreased myoinositol, leads to nerve conduction deficits. * **Microaneurysms (Option C):** Osmotic damage to retinal capillary pericytes weakens the vessel wall, leading to the characteristic outpouchings seen in diabetic retinopathy. ### High-Yield NEET-PG Pearls: * **Key Enzyme:** *Aldose Reductase* is the rate-limiting enzyme of the polyol pathway. * **Tissue Vulnerability:** "LURe" (Lens, Urethra/Kidney, Retina) and Nerves are most affected because they lack significant levels of *Sorbitol Dehydrogenase* (which converts sorbitol to fructose). * **Oxidative Stress:** The polyol pathway consumes NADPH, depleting the cell’s antioxidant capacity (reduced glutathione), further exacerbating damage.

Question 36: Which of the following is true regarding MEDNIK syndrome?

A. Caused by mutations in the AP1S1 gene.
B. A disorder of copper metabolism.
C. Mental retardation, deafness, and neuropathy are seen in this disorder.
D. All of the above. (Correct Answer)

Explanation: **Explanation:** **MEDNIK Syndrome** is a rare, multisystem autosomal recessive neurocutaneous disorder. The name is an acronym representing its core clinical features: **M**ental retardation, **E**nteropathy, **D**eafness, **N**europathy, **I**chthyosis, and **K**eratoderma. 1. **Genetic Basis (Option A):** It is caused by mutations in the **AP1S1 gene**, which encodes the small subunit of the adaptor protein complex 1 (AP-1). This complex is essential for intracellular protein trafficking between the Golgi apparatus and endosomes. 2. **Copper Metabolism (Option B):** MEDNIK syndrome is classified as a **disorder of copper metabolism**. The AP-1 complex deficiency leads to the mislocalization of copper transporters **ATP7A** (associated with Menkes disease) and **ATP7B** (associated with Wilson disease). Consequently, patients exhibit a unique biochemical profile: low serum copper and ceruloplasmin (like Menkes) but high liver copper (like Wilson). 3. **Clinical Features (Option C):** The syndrome presents with severe developmental delay (mental retardation), sensorineural deafness, and peripheral neuropathy, alongside congenital ichthyosis and chronic diarrhea (enteropathy). Since all three statements accurately describe the genetic, metabolic, and clinical aspects of the disease, **Option D** is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** * **Inheritance:** Autosomal Recessive. * **Key Mimic:** It can be mistaken for Menkes or Wilson disease due to overlapping copper profiles; however, the presence of **ichthyosis** and **enteropathy** is a major clinical differentiator. * **Treatment:** Oral **Zinc acetate** therapy has shown success in improving clinical symptoms and normalizing copper levels by inducing metallothionein. (No references were found to directly support MEDNIK syndrome specifically; generic references for IEMs and other syndromes were excluded).

Question 37: Hypercalcemia is associated with all of the following conditions, except:

A. Sarcoidosis
B. Celiac disease (Correct Answer)
C. Milk alkali syndrome
D. Hyperparathyroidism

Explanation: The correct answer is **Celiac disease**, which is typically associated with **hypocalcemia**, not hypercalcemia [2]. **1. Why Celiac Disease is the Correct Answer:** Celiac disease is a malabsorption syndrome characterized by gluten-sensitive enteropathy. Damage to the small intestinal mucosa leads to the malabsorption of fat-soluble vitamins, including **Vitamin D**. Deficiency in Vitamin D results in impaired intestinal calcium absorption [2]. Furthermore, unabsorbed fatty acids in the gut bind to ionized calcium (saponification), leading to its excretion in stool. This results in low serum calcium levels and a compensatory rise in PTH (Secondary Hyperparathyroidism) [3]. **2. Analysis of Incorrect Options:** * **Sarcoidosis:** Granulomatous diseases involve macrophages that express **1-alpha-hydroxylase**. This enzyme converts 25-hydroxyvitamin D into active 1,25-dihydroxyvitamin D (calcitriol), leading to increased intestinal calcium absorption and hypercalcemia [1]. * **Milk Alkali Syndrome:** Caused by excessive ingestion of calcium and absorbable antacids (calcium carbonate). It presents with the triad of hypercalcemia, metabolic alkalosis, and renal insufficiency [1]. * **Hyperparathyroidism:** Primary hyperparathyroidism (usually due to a parathyroid adenoma) is the most common cause of hypercalcemia in outpatient settings due to excessive PTH secretion [1], [4]. **3. NEET-PG High-Yield Pearls:** * **Most common cause of hypercalcemia (Outpatient):** Primary Hyperparathyroidism [4]. * **Most common cause of hypercalcemia (Inpatient):** Malignancy (often via PTHrP) [1]. * **ECG finding in Hypercalcemia:** Shortened QT interval. * **Thiazide diuretics** cause hypercalcemia, whereas **Loop diuretics** (Furosemide) cause hypocalcemia ("Loops Lose Calcium") [1].

Question 38: Which of the following conditions is associated with a normal serum alpha-fetoprotein level?

A. Ovarian dysgerminoma (Correct Answer)
B. Hepatoblastoma
C. Embryonal carcinoma
D. Yolk sac tumors

Explanation: **Explanation:** The measurement of serum tumor markers is a high-yield topic in NEET-PG, particularly for differentiating germ cell tumors (GCTs). **1. Why Ovarian Dysgerminoma is the Correct Answer:** Ovarian dysgerminoma is the female counterpart of the testicular seminoma. These tumors are characterized by primitive germ cells that have not undergone further differentiation. Consequently, they **do not produce Alpha-Fetoprotein (AFP)**. The characteristic markers for dysgerminoma are **Lactate Dehydrogenase (LDH)** and occasionally **hCG** (if syncytiotrophoblastic giant cells are present). **2. Analysis of Incorrect Options:** * **Hepatoblastoma:** This is the most common primary liver tumor in children. It is classically associated with extremely high levels of AFP, which serves as a diagnostic and prognostic tool. * **Yolk Sac Tumors (Endodermal Sinus Tumors):** These tumors differentiate toward yolk sac structures. Since the fetal yolk sac is the primary physiological source of AFP, these tumors are the **most characteristic producers of AFP**. * **Embryonal Carcinoma:** This is a primitive, pleomorphic GCT. It often produces **both AFP and hCG**, as it contains cells capable of differentiating into both yolk sac and trophoblastic lineages. **Clinical Pearls for NEET-PG:** * **AFP** is elevated in: Yolk sac tumors, Hepatocellular carcinoma (HCC), Hepatoblastoma, and Neural Tube Defects (in maternal serum). * **Pure Dysgerminoma/Seminoma:** AFP is **always normal**. If AFP is elevated in a suspected dysgerminoma, it indicates a mixed germ cell tumor (likely a yolk sac component). * **Schiller-Duval bodies** are the histopathological hallmark of Yolk Sac Tumors. * **LDH** is the most sensitive (though non-specific) marker for monitoring Dysgerminoma.

Question 39: A 30-year-old woman complains of weakness and fatigability over the past 6 months. She has a 3-month acute history of severe hypertension that has required treatment with antihypertensive medications. Radiographic examination reveals a tumor of her right suprarenal gland. The patient is diagnosed with a pheochromocytoma (tumor of the adrenal medulla) and is scheduled for a laparoscopic adrenalectomy. Which of the following nerve fibers will need to be cut when the adrenal gland and tumor are removed?

A. Preganglionic sympathetic fibers (Correct Answer)
B. Postganglionic sympathetic fibers
C. Somatic motor fibers
D. Postganglionic parasympathetic fibers

Explanation: ### Explanation **1. Why Preganglionic Sympathetic Fibers is Correct:** The adrenal medulla is embryologically and functionally unique. It is derived from **neural crest cells** and is considered a **modified sympathetic ganglion**. Unlike other effector organs in the sympathetic nervous system, which receive postganglionic fibers, the chromaffin cells of the adrenal medulla are directly innervated by **preganglionic sympathetic fibers** (primarily via the Greater Splanchnic nerve). These fibers release acetylcholine (ACh), which triggers the chromaffin cells to release epinephrine and norepinephrine directly into the bloodstream. Therefore, during an adrenalectomy, these preganglionic fibers must be severed. **2. Why the Other Options are Incorrect:** * **Postganglionic sympathetic fibers:** These typically originate in the paravertebral or prevertebral ganglia and travel to target organs (e.g., heart, blood vessels). The adrenal medulla itself acts as the "postganglionic neuron," so it does not receive postganglionic input. * **Somatic motor fibers:** These innervate skeletal muscles under voluntary control. The adrenal gland is an endocrine organ under autonomic control. * **Postganglionic parasympathetic fibers:** The adrenal medulla does not have a functional parasympathetic nerve supply; its secretion is regulated purely by the sympathetic nervous system. **3. High-Yield Clinical Pearls for NEET-PG:** * **Rule of 10s for Pheochromocytoma:** 10% bilateral, 10% malignant, 10% extra-adrenal (Paraganglioma), 10% pediatric, and 10% familial. * **Surgical Management:** In pheochromocytoma surgery, **Alpha-blockade (e.g., Phenoxybenzamine)** must be started 7–14 days *before* Beta-blockade to prevent a hypertensive crisis (unopposed alpha-stimulation). [1] * **Neurotransmitter:** The preganglionic fibers to the adrenal medulla are **cholinergic** (release ACh), even though the medulla's output is adrenergic.

Question 40: Which of the following is seen in 95% of patients with diabetes mellitus?

A. HLAB27
B. HLAB3-B4
C. HLA DR3-DR4 (Correct Answer)
D. HLAA3

Explanation: ### Explanation **Correct Option: C. HLA DR3-DR4** The association between Human Leukocyte Antigens (HLA) and Type 1 Diabetes Mellitus (T1DM) is one of the strongest in medical genetics [2]. Approximately **95% of Caucasians with T1DM** express either **HLA-DR3 or HLA-DR4**, compared to about 40% of the general population. Specifically, the inheritance of the **DR3/DR4 heterozygote** genotype confers the highest genetic risk for the development of the disease. These MHC Class II molecules are responsible for presenting islet autoantigens to T-helper cells, triggering the autoimmune destruction of pancreatic beta cells. **Explanation of Incorrect Options:** * **A. HLA-B27:** This is a Class I MHC antigen strongly associated with **Seronegative Spondyloarthropathies**, most notably Ankylosing Spondylitis (90% association), Reiter’s syndrome, and Psoriatic arthritis. * **B. HLA B3-B4:** These are not standard high-yield HLA associations for diabetes. While various B-locus alleles (like B8 and B15) show some linkage disequilibrium with DR3/DR4, they are not the primary diagnostic markers. * **D. HLA-A3:** This allele is classically associated with **Hereditary Hemochromatosis**. **High-Yield Clinical Pearls for NEET-PG:** * **T1DM Risk:** If one sibling has T1DM, the risk to another sibling is 5%; if they share the same HLA haplotype, the risk increases to 10–20% [1]. * **Protective Allele:** While DR3/DR4 increases risk, **HLA-DQB1*0602** is known to provide potent protection against T1DM. * **Other HLA-DR Associations:** * **DR2:** Multiple Sclerosis, SLE, Goodpasture Syndrome. * **DR3:** T1DM, SLE, Graves' Disease, Celiac Disease [1]. * **DR4:** T1DM, Rheumatoid Arthritis. * **DR5:** Hashimoto Thyroiditis.

Practice by Chapter

Diabetes Mellitus

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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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