Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 761: Which one of the following clinical features is NOT typically seen in pheochromocytoma?

A. Hypertension
B. Episodic palpitations
C. Weight loss
D. Diarrhea (Correct Answer)

Explanation: **Explanation** Pheochromocytoma is a catecholamine-secreting tumor arising from the chromaffin cells of the adrenal medulla. The clinical presentation is primarily driven by the excessive release of epinephrine and norepinephrine, which stimulate the sympathetic nervous system. **Why "Diarrhea" is the correct answer:** Catecholamines stimulate **alpha-adrenergic receptors** in the gastrointestinal tract, which leads to **decreased intestinal motility** and contraction of sphincters. Consequently, patients with pheochromocytoma typically experience **constipation**, not diarrhea. If a patient presents with a neuroendocrine tumor and diarrhea, clinicians should instead suspect Medullary Thyroid Carcinoma (secreting calcitonin) or Carcinoid Syndrome (secreting serotonin) [1]. **Why the other options are incorrect:** * **Hypertension (A):** The most common clinical sign. It can be sustained or paroxysmal due to alpha-1 mediated vasoconstriction. * **Episodic Palpitations (B):** Part of the classic triad (Headache, Sweating, Palpitations). It is caused by the beta-1 adrenergic effect on the heart, increasing heart rate and contractility. * **Weight Loss (C):** Catecholamines are catabolic; they increase the basal metabolic rate and promote glycogenolysis and lipolysis, leading to weight loss despite a normal appetite. **High-Yield Clinical Pearls for NEET-PG:** * **The Rule of 10s:** 10% are bilateral, 10% are extra-adrenal (Paragangliomas), 10% are malignant, and 10% occur in children. * **Diagnosis:** Best initial screening test is **24-hour urinary fractionated metanephrines** or plasma free metanephrines. * **Management:** Always give **Alpha-blockers first** (e.g., Phenoxybenzamine) for 10–14 days before Beta-blockers to avoid a hypertensive crisis (unopposed alpha-stimulation). * **Associations:** MEN 2A and 2B, von Hippel-Ludlau (VHL) syndrome, and NF-1.

Question 762: What is the most common cause of hypothyroidism in adults?

A. Trauma
B. Radioactive iodine ingestion
C. Primary hypothyroidism (Correct Answer)
D. Parathyroid surgery

Explanation: Hypothyroidism is a common endocrine disorder characterized by a deficiency of thyroid hormones. The correct answer is **Primary Hypothyroidism**, which refers to a failure of the thyroid gland itself to produce sufficient hormones [1]. **1. Why Primary Hypothyroidism is correct:** Primary hypothyroidism accounts for over 95% of all clinical cases. In iodine-sufficient regions (like most urban populations), the most common specific cause of primary hypothyroidism is **Hashimoto’s Thyroiditis** (an autoimmune destruction of the gland) [1]. Globally, however, **iodine deficiency** remains the most common cause of primary hypothyroidism. **2. Why other options are incorrect:** * **Trauma (A):** Direct physical trauma to the neck rarely results in permanent hypothyroidism as the gland is well-protected and has a high compensatory capacity. * **Radioactive Iodine Ingestion (B):** While I-131 therapy (used for Graves' disease or thyroid cancer) causes "iatrogenic" primary hypothyroidism, it is a specific medical intervention and not the most common cause in the general adult population. * **Parathyroid Surgery (D):** Hypothyroidism is a risk during a total thyroidectomy, but isolated parathyroid surgery typically spares the thyroid gland. The most common complication of parathyroid surgery is hypocalcemia, not hypothyroidism. **Clinical Pearls for NEET-PG:** * **Most common cause worldwide:** Iodine deficiency. * **Most common cause in iodine-replete areas:** Hashimoto’s Thyroiditis (associated with anti-TPO and anti-TG antibodies) [1]. * **Screening:** Serum **TSH** is the most sensitive initial test for primary hypothyroidism (TSH will be elevated) [1]. * **Secondary Hypothyroidism:** Refers to pituitary failure (low TSH, low T4), which is much rarer than primary causes [1].

Question 763: A 40-year-old woman with hypertension presents with excessive thirst, excessive urination, constipation, and a depressed mood. Her medications include hydrochlorothiazide. Laboratory studies show a serum calcium level of 11.0 mg/dL. Which of the following underlying disorders is most likely?

A. Medullary carcinoma of the thyroid
B. Multiple myeloma
C. Parathyroid adenoma (Correct Answer)
D. Porphyria

Explanation: **Explanation:** The patient presents with the classic "stones, bones, abdominal groans, and psychic overtones" of **hypercalcemia** (thirst, polyuria, constipation, and depressed mood). In an outpatient setting, the most common cause of asymptomatic or mildly symptomatic hypercalcemia is **Primary Hyperparathyroidism (PHPT)**, usually caused by a solitary **parathyroid adenoma** (85% of cases) [1]. 1. **Why Parathyroid Adenoma is correct:** PHPT leads to autonomous secretion of Parathyroid Hormone (PTH), which increases bone resorption and renal calcium reabsorption [2]. While hydrochlorothiazide can cause mild hypercalcemia, it often unmasks underlying PHPT [1]. The combination of chronic symptoms and a calcium level of 11.0 mg/dL strongly points toward an adenoma [3]. 2. **Why other options are incorrect:** * **Medullary carcinoma of the thyroid:** This secretes **calcitonin**, which typically lowers serum calcium levels [1]. It is associated with MEN 2A/2B, but the cancer itself does not cause hypercalcemia. * **Multiple myeloma:** While it causes hypercalcemia via osteoclast activation, it usually presents with "CRAB" features: Calcium elevation, Renal failure, Anemia, and Bone (lytic) lesions [1]. It is less likely in a 40-year-old with a mild, chronic presentation [3]. * **Porphyria:** Acute intermittent porphyria presents with abdominal pain and neuropsychiatric symptoms, but it is **not** associated with hypercalcemia. **NEET-PG High-Yield Pearls:** * **Most common cause of hypercalcemia:** Outpatient = PHPT; Inpatient = Malignancy [1]. * **EKG finding in hypercalcemia:** Shortened QT interval. * **Thiazide Diuretics:** These decrease urinary calcium excretion ("Thiazides throw sodium but save calcium"), which can unmask PHPT [1]. * **Diagnosis of PHPT:** Elevated Serum Calcium + Elevated/Inappropriately Normal PTH [1][3].

Question 764: What is the most common sign or symptom of pheochromocytoma?

A. Hypertension (Correct Answer)
B. Headache
C. Sweating
D. Palpitation

Explanation: **Explanation:** **Pheochromocytoma** is a catecholamine-secreting tumor arising from the chromaffin cells of the adrenal medulla. Understanding its presentation is crucial for NEET-PG, as it is often referred to as the "10% tumor." **Why Hypertension is the Correct Answer:** **Hypertension** is the **most common clinical sign**, occurring in approximately 90% of patients [1]. It results from the excessive secretion of norepinephrine and epinephrine, which cause potent vasoconstriction and increased cardiac output. The hypertension can be **sustained** (more common) or **paroxysmal** (classic "spells"). While the "classic triad" (Headache, Sweating, Palpitations) is highly specific when all three are present, hypertension remains the most frequent finding overall. **Analysis of Incorrect Options:** * **B, C, and D (Headache, Sweating, Palpitation):** These constitute the **Classic Triad**. While they are the most common *symptoms* during a paroxysmal attack, they occur less frequently than hypertension. Among the triad, **Headache** is the most common symptom (approx. 80%), followed by generalized sweating (65%) and palpitations (60%). **High-Yield Clinical Pearls for NEET-PG:** * **Rule of 10s:** 10% are bilateral, 10% are extra-adrenal (Paragangliomas), 10% are malignant, and 10% are familial. * **Best Screening Test:** Plasma free metanephrines (High sensitivity). * **Best Confirmatory Test:** 24-hour urinary fractionated metanephrines and catecholamines (High specificity). * **Pre-operative Management:** Always give **Alpha-blockers first** (e.g., Phenoxybenzamine) followed by Beta-blockers to avoid a hypertensive crisis (unopposed alpha-stimulation). * **Associated Syndromes:** MEN 2A, MEN 2B, von Hippel-Lindau (VHL), and NF-1.

Question 765: What is the most common cause of euvolemic hyponatremia?

A. Hypothyroidism
B. Hypoadrenalism
C. Hyperthyroidism
D. Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) (Correct Answer)

Explanation: **Explanation:** **1. Why SIADH is the Correct Answer:** The **Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH)** is the most common cause of euvolemic hyponatremia [1]. The underlying pathophysiology involves the non-physiological release of ADH, which leads to excessive water reabsorption in the renal collecting ducts via insertion of aquaporin (AQP-2) channels [1]. This causes **dilutional hyponatremia**. While there is a slight increase in total body water, the body compensates via **pressure natriuresis** (excreting sodium and water), which prevents clinical edema or hypertension, maintaining a state of "euvolemia." **2. Why the Other Options are Incorrect:** * **Hypothyroidism (A):** While severe hypothyroidism (Myxedema) can cause hyponatremia by reducing free water clearance, it is a much less frequent cause compared to SIADH [1]. * **Hypoadrenalism (B):** Primary adrenal insufficiency (Addison’s disease) typically causes **hypovolemic hyponatremia** (due to mineralocorticoid deficiency leading to salt wasting) [1]. Secondary adrenal insufficiency can cause euvolemic hyponatremia, but it is statistically less common than SIADH [3]. * **Hyperthyroidism (C):** This is not a recognized cause of hyponatremia; in fact, it has no direct association with the syndrome of euvolemic hyponatremia. **3. NEET-PG High-Yield Pearls:** * **Diagnostic Criteria for SIADH:** Low serum osmolality (<275 mOsm/kg), inappropriately high urine osmolality (>100 mOsm/kg), and high urine sodium (>40 mEq/L) in a clinically euvolemic patient. * **Common Triggers:** Small cell lung cancer (paraneoplastic), CNS disorders (stroke, trauma), and drugs (SSRIs, Carbamazepine, Cyclophosphamide) [2]. * **Management:** Fluid restriction is the first-line treatment [2]. For severe/symptomatic cases, use 3% hypertonic saline, ensuring the rate of correction does not exceed **8–10 mmol/L in 24 hours** to avoid **Osmotic Demyelination Syndrome (ODS)** [2].

Question 766: Insulin resistance syndrome includes which of the following?

A. Dyslipidemia (Correct Answer)
B. Hypertension
C. Hyperuricemia
D. High HDL

Explanation: **Explanation:** Insulin Resistance Syndrome, also known as **Metabolic Syndrome** or Syndrome X, is a cluster of metabolic abnormalities that significantly increase the risk of cardiovascular disease and Type 2 Diabetes Mellitus. **Why Dyslipidemia is correct:** In the state of insulin resistance, there is an increased flux of free fatty acids to the liver and impaired suppression of lipolysis in adipose tissue. This leads to a characteristic **atherogenic dyslipidemia** triad: 1. **Hypertriglyceridemia** (Elevated VLDL) 2. **Low HDL levels** [1] 3. **Small, dense LDL particles** [1] **Analysis of Options:** * **A. Dyslipidemia (Correct):** This is a hallmark feature. Specifically, high triglycerides and low HDL are diagnostic criteria. * **B & C. Hypertension and Hyperuricemia:** While both are frequently *associated* with insulin resistance, they are often considered secondary manifestations or associated findings rather than the core metabolic definition used in standard diagnostic criteria (like NCEP ATP III or IDF). In many MCQ formats, if "Dyslipidemia" is an option, it is prioritized as a primary metabolic component. * **D. High HDL (Incorrect):** Insulin resistance is characterized by **Low HDL** (typically <40 mg/dL in men and <50 mg/dL in women) [1]. **High-Yield NEET-PG Pearls:** * **Diagnostic Criteria (NCEP ATP III):** Requires 3 out of 5: 1. Abdominal obesity (Waist circumference >102cm M, >88cm F) 2. Triglycerides ≥150 mg/dL [1] 3. HDL <40 mg/dL (M) or <50 mg/dL (F) 4. Blood Pressure ≥130/85 mmHg 5. Fasting Glucose ≥100 mg/dL * **Acanthosis Nigricans:** A key clinical sign of insulin resistance. * **PCOS:** Strongly linked with insulin resistance syndrome in women.

Question 767: Autonomic Polyglandular syndrome 2 is associated with Adrenocortical insufficiency and which of the following?

A. Primary Gastric Adenocarcinoma
B. Hashimoto's thyroiditis
C. Islet cell adenoma
D. Type 1 diabetes mellitus (Correct Answer)

Explanation: **Autoimmune Polyglandular Syndrome Type 2 (APS-2)**, also known as Schmidt’s Syndrome, is a rare polyendocrine disorder characterized by the presence of **Addison’s disease** (adrenocortical insufficiency) in combination with **Type 1 Diabetes Mellitus** and/or **Autoimmune Thyroid Disease** (usually Graves' disease or Hashimoto’s thyroiditis) [1]. ### **Why Type 1 Diabetes Mellitus is Correct?** APS-2 is defined by the clinical triad of Addison’s disease, Type 1 Diabetes (Carpenter’s Syndrome), and Autoimmune Thyroid Disease. It is an HLA-linked (HLA-DR3/DR4) polygenic disorder that typically manifests in young adulthood (3rd–4th decade). Type 1 DM is a classic component of this syndrome due to the shared autoimmune destruction of endocrine glands [1]. ### **Why Other Options are Incorrect:** * **A. Primary Gastric Adenocarcinoma:** While Pernicious Anemia (atrophic gastritis) can occur in APS-2, gastric adenocarcinoma is not a defining component. * **B. Hashimoto's thyroiditis:** While Hashimoto’s is associated with APS-2, the question asks for the most definitive association alongside Addison's. In many standardized formats, Type 1 DM is the specific partner that defines "Carpenter’s Syndrome" within APS-2. (Note: Both B and D are associated, but D is a more frequent "textbook" association for this specific question stem). * **C. Islet cell adenoma:** This is a feature of **MEN-1 (Multiple Endocrine Neoplasia Type 1)**, not an autoimmune syndrome [1]. APS involves gland destruction, not neoplastic hyperplasia. ### **High-Yield Clinical Pearls for NEET-PG:** * **APS Type 1 (PEC):** Characterized by **P**arathyroidism (Hypo), **E**nteropathy/Candidiasis (Mucocutaneous), and **C**irrhosis/Adrenal failure [1]. It is caused by a mutation in the **AIRE gene**. * **APS Type 2 (Schmidt’s):** More common than Type 1; involves Adrenal failure + Thyroid disease + Type 1 DM [1]. * **Clinical Warning:** In a patient with APS-2, always treat the **Adrenal Insufficiency first**. Starting thyroxine before glucocorticoids can precipitate an acute adrenal crisis by increasing the metabolic clearance of cortisol.

Question 768: A 28-year-old male presents with ophthalmoplegic signs of thyrotoxicosis. All of the following can be considered in the differential diagnosis of the case, EXCEPT:

A. Diffuse thyroid goiter
B. Hashimoto's Thyroiditis
C. Riedel's Thyroiditis (Correct Answer)
D. Adenomatous goiter

Explanation: **Explanation:** The question focuses on identifying which thyroid conditions are associated with **Graves' ophthalmopathy** (thyroid-associated orbitopathy). The hallmark of this condition is the presence of TSH-receptor antibodies (TRAb), which react with orbital fibroblasts, leading to inflammation and proptosis [1]. **Why Riedel’s Thyroiditis is the correct answer:** Riedel’s thyroiditis is a rare chronic inflammatory disease characterized by dense fibrous tissue replacing the thyroid parenchyma and extending into adjacent neck structures. It is often considered part of the **IgG4-related systemic disease** spectrum. While it can cause hypothyroidism, it is **not** an autoimmune thyrotoxic state and does not involve TSH-receptor antibodies. Therefore, it does not present with ophthalmoplegic signs of thyrotoxicosis. **Analysis of Incorrect Options:** * **Diffuse Thyroid Goiter (Graves' Disease):** This is the most common cause of thyrotoxicosis and is classically associated with ophthalmopathy due to the presence of TRAb [1]. * **Hashimoto's Thyroiditis:** Although typically causing hypothyroidism, Hashimoto’s can present with a transient thyrotoxic phase ("Hashitoxicosis"). Furthermore, patients with Hashimoto’s can rarely harbor TSH-receptor antibodies, leading to clinical ophthalmopathy. * **Adenomatous Goiter:** In some cases of toxic multinodular goiter (which can arise from a long-standing adenomatous goiter), patients may develop "Marine-Lenhart Syndrome"—the coexistence of Graves' disease with functioning nodules—resulting in ophthalmopathy. **High-Yield Clinical Pearls for NEET-PG:** * **Graves' Triad:** Hyperthyroidism, Diffuse Goiter, and Exophthalmos (Ophthalmopathy) [1]. * **Riedel’s Thyroiditis:** Characterized by a "stony hard," fixed, painless goiter. It can mimic anaplastic carcinoma but occurs in younger patients. * **Smoking:** The most significant modifiable risk factor for the progression of Graves' ophthalmopathy. * **Treatment:** Steroids are the first-line medical management for active, severe Graves' ophthalmopathy [1].

Question 769: Factitious hyperinsulinemia is differentiated from insulinoma by which of the following?

A. C-peptide levels (Correct Answer)
B. Insulin antibodies
C. Serum glucose level
D. None of the above

Explanation: The differentiation between **Insulinoma** (an endogenous insulin-secreting tumor) and **Factitious Hyperinsulinemia** (exogenous administration of insulin) is a classic high-yield topic in endocrinology. **1. Why C-peptide levels are correct:** Insulin is synthesized in the pancreatic beta cells as **proinsulin**, which is then cleaved into equimolar amounts of **Insulin** and **C-peptide**. [1] * In **Insulinoma**, there is autonomous endogenous production, leading to **elevated** levels of both Insulin and C-peptide. [1] * In **Factitious Hyperinsulinemia** (exogenous insulin injection), the patient has high serum insulin, but because exogenous insulin does not contain C-peptide, the body’s endogenous production is suppressed via negative feedback. This results in **low/suppressed C-peptide** levels. [1] **2. Why other options are incorrect:** * **Insulin antibodies:** While these can be present in patients using older insulin formulations or those with Insulin Autoimmune Syndrome (Hirata disease), they are not the primary diagnostic tool to differentiate between these two specific conditions. * **Serum glucose level:** Both conditions present with profound **hypoglycemia**. [2] Therefore, blood glucose cannot distinguish the source of the excess insulin. **Clinical Pearls for NEET-PG:** * **Whipple’s Triad:** Essential for diagnosing insulinoma (Symptoms of hypoglycemia, low plasma glucose, and relief of symptoms after glucose administration). * **Sulfonylurea Screening:** If a patient has high insulin and high C-peptide, you must screen the urine/serum for oral hypoglycemic agents (Sulfonylureas) to rule out factitious ingestion of pills, which mimics an insulinoma. [1] * **Proinsulin:** Usually elevated (>25%) in patients with insulinoma.

Question 770: Which of the following tests is most sensitive for detecting early diabetic nephropathy?

A. Serum Creatinine
B. Creatinine clearance
C. Microalbuminuria (Correct Answer)
D. Ultrasonography

Explanation: **Explanation:** **Microalbuminuria** is the earliest clinical marker of diabetic nephropathy [1]. It refers to the excretion of small amounts of albumin (30–300 mg/day or an albumin-to-creatinine ratio of 30–300 mg/g) that are not detectable by standard urine dipstick tests [1]. In the natural history of diabetic kidney disease, glomerular hyperfiltration occurs first, followed by microalbuminuria. Detecting it at this stage is crucial because it represents a **reversible** phase where strict glycemic control and ACE inhibitors/ARBs can halt or delay progression to overt proteinuria. **Why other options are incorrect:** * **Serum Creatinine:** This is a late marker. It typically remains within the normal range until approximately 50% of the nephron function is lost. * **Creatinine Clearance:** While it measures the Glomerular Filtration Rate (GFR), it is not the most sensitive early marker. In early diabetes, GFR may actually be *increased* (hyperfiltration), making it an unreliable screening tool for early damage compared to albumin leakage. * **Ultrasonography:** USG is used to assess kidney size and rule out obstruction. In diabetic nephropathy, kidneys are characteristically **enlarged** or normal-sized even in advanced stages, but USG cannot detect early functional or microscopic damage. **High-Yield Clinical Pearls for NEET-PG:** * **Screening:** Start screening for microalbuminuria 5 years after diagnosis in Type 1 DM and **at the time of diagnosis** in Type 2 DM. * **Gold Standard:** The preferred screening method is the **random spot urine albumin-to-creatinine ratio (ACR)**. * **Definition of Overt Nephropathy:** Persistent albuminuria >300 mg/day (Macroalbuminuria). * **Kimmelstiel-Wilson (KW) lesions:** The pathognomonic histological finding (nodular glomerulosclerosis) seen on biopsy [2].

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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