Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 581: Which of the following is NOT associated with thymoma?

A. Red cell aplasia
B. Myasthenia gravis
C. Hypergammaglobulinemia (Correct Answer)
D. Compression of the mediastinum

Explanation: **Explanation:** Thymomas are epithelial tumors of the thymus gland, frequently associated with various paraneoplastic syndromes due to the thymus's role in immune self-tolerance. **Why Option C is the correct answer:** Thymoma is characteristically associated with **Hypogammaglobulinemia** (specifically **Good Syndrome**), not hypergammaglobulinemia. Good Syndrome is a rare immunodeficiency characterized by thymoma, low B-cell counts, and low serum immunoglobulin levels, leading to increased susceptibility to infections. **Analysis of Incorrect Options:** * **Option A (Red cell aplasia):** Pure Red Cell Aplasia (PRCA) is a well-known paraneoplastic manifestation of thymoma. Approximately 5-15% of patients with PRCA have a thymoma, and surgical removal of the tumor can sometimes lead to hematologic remission. * **Option B (Myasthenia gravis):** This is the most common association [1]. About 30-45% of patients with thymoma have Myasthenia Gravis (MG), and conversely, 10-15% of patients with MG are found to have a thymoma [1]. * **Option D (Compression of the mediastinum):** As thymomas are anterior mediastinal masses, they can grow large enough to cause local "mass effect" symptoms, including superior vena cava (SVC) syndrome, cough, dyspnea, and chest pain. **High-Yield Clinical Pearls for NEET-PG:** * **Good Syndrome:** Thymoma + Hypogammaglobulinemia + Low B-cells. * **Most common anterior mediastinal mass:** Thymoma (in adults). * **The "4 Ts" of Anterior Mediastinal Masses:** Thymoma, Teratoma (Germ cell tumors), Thyroid (Retrosternal goiter), and "Terrible" Lymphoma. * **Diagnosis:** Contrast-enhanced CT (CECT) is the imaging modality of choice [1].

Question 582: In phaeochromocytoma, what substance will be present in elevated amounts in the urine?

A. Vanillylmandelic acid (VMA) (Correct Answer)
B. 5-hydroxyindoleacetic acid (HIAA)
C. Both VMA and HIAA
D. Neither VMA nor HIAA

Explanation: PHAEOCROMOCYTOMA EXPLANATION: **1. Why Vanillylmandelic acid (VMA) is correct:** Pheochromocytoma is a catecholamine-secreting tumor arising from the chromaffin cells of the adrenal medulla [1]. These tumors overproduce epinephrine and norepinephrine. These catecholamines are metabolized by enzymes (COMT and MAO) into intermediate metabolites called **metanephrines** and finally into the end-product, **Vanillylmandelic acid (VMA)**. Because these substances are excreted by the kidneys, elevated levels of urinary VMA (measured via a 24-hour urine collection) serve as a classic biochemical marker for diagnosing pheochromocytoma. **2. Why the other options are incorrect:** * **5-hydroxyindoleacetic acid (5-HIAA):** This is the primary metabolite of **serotonin**. It is the gold-standard urinary marker for **Carcinoid Syndrome**, not pheochromocytoma. * **Option C & D:** Since VMA is specific to catecholamine metabolism and 5-HIAA is specific to serotonin metabolism, they represent two distinct clinical entities. **3. NEET-PG High-Yield Clinical Pearls:** * **Best Initial Screening Test:** Plasma free metanephrines (highest sensitivity). * **Confirmatory Test:** 24-hour urinary metanephrines and VMA (high specificity). * **Rule of 10s:** 10% are bilateral, 10% are malignant, 10% are extra-adrenal (Paragangliomas), and 10% occur in children [1]. * **Clinical Triad:** Episodic headache, sweating (diaphoresis), and tachycardia/palpitations in a hypertensive patient. * **Pre-operative Management:** Always give **Alpha-blockers first** (e.g., Phenoxybenzamine) followed by Beta-blockers to prevent a hypertensive crisis.

Question 583: Which one of the following is not a feature of Klinefelter's syndrome?

A. Gynecomastia
B. Eunuchoid habitus
C. Short 4th metacarpal (Correct Answer)
D. Hypogonadism

Explanation: **Explanation:** **Klinefelter’s Syndrome (47, XXY)** is the most common cause of primary hypogonadism in males. [1] The correct answer is **Short 4th metacarpal**, as this is a classic clinical feature of **Turner’s Syndrome (45, XO)** and Pseudohypoparathyroidism, not Klinefelter’s. [2] **Analysis of Options:** * **Short 4th metacarpal (Correct Answer):** Also known as **Archibald’s sign**, this is a skeletal deformity associated with Turner’s syndrome. [2] In Klinefelter’s, skeletal findings typically involve increased limb length rather than shortening of metacarpals. [1] * **Gynecomastia:** Present in approximately 40-50% of cases due to an increased estrogen-to-androgen ratio. It also carries a significantly higher risk of male breast cancer. [3] * **Eunuchoid habitus:** Characterized by tall stature, long legs (lower segment > upper segment), and a decreased arm span-to-height ratio. [1] This occurs because testosterone deficiency leads to delayed epiphyseal closure. * **Hypogonadism:** Patients exhibit primary testicular failure characterized by small, firm testes (usually <2 cm), azoospermia (infertility), and low testosterone levels with compensatory elevations in LH and FSH. [1] **High-Yield Clinical Pearls for NEET-PG:** * **Karyotype:** Most commonly 47, XXY due to meiotic non-disjunction. * **Histology:** Testicular biopsy shows **hyalinization and fibrosis of seminiferous tubules** and Leydig cell hyperplasia. [1] * **Lab Findings:** ↓ Testosterone, ↑ FSH, ↑ LH, ↑ Estradiol. [1] * **Associated Risks:** Increased risk of Germ Cell Tumors (especially mediastinal), Breast Cancer, and autoimmune diseases (SLE). [3] * **Psychosocial:** Often associated with mild intellectual disability or learning delays. [1]

Question 584: The classic triad of pheochromocytoma includes episodes of all of the following except:

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

Explanation: The correct answer is **Hypertension**. ### **Explanation** While **hypertension** is the most common clinical sign of pheochromocytoma (present in >90% of cases), it is **not** part of the "classic symptomatic triad." The triad refers specifically to the paroxysmal symptoms experienced by the patient during a catecholamine surge. The classic clinical triad consists of: 1. **Headache** (most common symptom) 2. **Sweating** (diaphoresis) 3. **Palpitations** (tachycardia) The presence of all three symptoms plus hypertension has a specificity of over 90% for pheochromocytoma. However, because hypertension is a physical finding (sign) rather than a symptom in the triad, it is the "except" in this question. ### **Analysis of Options** * **A, B, and C (Palpitations, Headache, Sweating):** These constitute the classic triad. They occur in paroxysms ("spells") due to the episodic release of epinephrine and norepinephrine from the adrenal medulla tumor. * **D (Hypertension):** Although it is the most common feature, it is categorized as a **clinical sign**. Hypertension in pheochromocytoma can be sustained (60%) or paroxysmal (40%). ### **NEET-PG High-Yield Pearls** * **Rule of 10s:** 10% bilateral, 10% malignant, 10% pediatric, 10% extra-adrenal (Paraganglioma), and 10% 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). * **Genetic Associations:** MEN 2A, MEN 2B, VHL syndrome, and NF-1.

Question 585: Which of the following statements regarding the lipid abnormalities seen in patients with type 2 diabetes mellitus is incorrect?

A. Increase in hepatic VLDL production
B. Decrease in plasma levels of HDL cholesterol
C. Elevated levels of plasma LDL cholesterol (Correct Answer)
D. Elevated plasma triglycerides

Explanation: The characteristic pattern of dyslipidemia in Type 2 Diabetes Mellitus (T2DM) is known as "Diabetic Dyslipidemia." It is primarily driven by insulin resistance rather than a simple elevation of total cholesterol. In T2DM, the absolute level of LDL cholesterol is typically not significantly elevated compared to the general population. Instead, the abnormality lies in the quality of the LDL particles. Due to high triglyceride levels, LDL particles undergo remodeling to become small, dense LDL (sdLDL) [1]. These particles are more atherogenic because they easily penetrate the arterial wall and are more susceptible to oxidation [1]. Insulin resistance leads to increased lipolysis in adipose tissue, flooding the liver with free fatty acids [3]. This stimulates the overproduction of VLDL (rich in triglycerides), leading to hypertriglyceridemia [1]. High VLDL levels trigger an exchange where HDL loses cholesterol and gains triglycerides via CETP [1]. These triglyceride-rich HDL particles are rapidly cleared by hepatic lipase, resulting in low plasma HDL levels [1]. Reduced activity of Lipoprotein Lipase (LPL) in insulin-deficient states contributes to decreased clearance of VLDL and chylomicrons [2].

Question 586: Bronze diabetes is seen in which of the following conditions?

A. Wilson's disease
B. Sarcoidosis
C. Lead intoxication
D. Hemochromatosis (Correct Answer)

Explanation: **Explanation:** **Bronze Diabetes** is the classic clinical triad associated with **Hereditary Hemochromatosis**, an autosomal recessive disorder characterized by excessive intestinal iron absorption [1]. The condition leads to systemic iron overload, where iron (hemosiderin) is deposited in various organs, causing oxidative damage and fibrosis. The term "Bronze Diabetes" specifically refers to the combination of: 1. **Hyperpigmentation:** Iron deposition in the skin, combined with increased melanin production, gives the skin a characteristic metallic/bronze hue [1]. 2. **Diabetes Mellitus:** Iron deposition in the pancreas causes selective destruction of beta cells in the Islets of Langerhans, leading to secondary insulin deficiency [1], [3]. **Analysis of Incorrect Options:** * **Wilson’s Disease:** This is a disorder of **copper** metabolism [4]. While it affects the liver and brain (basal ganglia), it does not typically cause the skin bronzing or pancreatic failure seen in hemochromatosis. Key findings include Kayser-Fleischer rings and low ceruloplasmin [4]. * **Sarcoidosis:** A multisystem granulomatous disease. While it can involve the pancreas or skin (Lupus pernio), it does not present with the specific "bronze diabetes" triad. * **Lead Intoxication:** Presents with abdominal colic, peripheral neuropathy (wrist drop), and "Burtonian lines" on the gums, but is not associated with iron overload or diabetes. **High-Yield Clinical Pearls for NEET-PG:** * **Gene Mutation:** Most commonly the **HFE gene** (C282Y mutation) on Chromosome 6 [1], [2]. * **Classic Triad:** Cirrhosis, Diabetes, and Skin Pigmentation [1]. * **Other Features:** Dilated cardiomyopathy, "Square-off" bone ends (arthropathy of 2nd/3rd MCP joints), and Hypogonadotropic hypogonadism. * **Diagnosis:** Best initial test is **Transferrin Saturation** (>45%); Gold standard is Liver Biopsy (Prussian Blue stain) [2]. * **Treatment:** Therapeutic phlebotomy is the treatment of choice [2].

Question 587: All of the following can commonly occur in a patient who suffered a decelerating injury with damaged pituitary stalk, except one?

A. Diabetes mellitus (Correct Answer)
B. Thyroid insufficiency
C. Adrenocortical insufficiency
D. Diabetes insipidus

Explanation: **Explanation:** A decelerating injury (such as a motor vehicle accident) can cause shearing of the **pituitary stalk** (infundibulum), which disconnects the hypothalamus from the pituitary gland. This results in **Panhypopituitarism** and a disruption of the transport of ADH [2]. **Why Diabetes Mellitus is the correct answer:** Diabetes Mellitus (DM) is a disorder of insulin deficiency or resistance leading to hyperglycemia. It is unrelated to the pituitary gland or the hypothalamus. Pituitary stalk damage actually leads to a *decrease* in growth hormone and ACTH (cortisol), both of which are counter-regulatory hormones [1]. Therefore, stalk damage would technically increase insulin sensitivity rather than causing Diabetes Mellitus [1]. **Analysis of Incorrect Options:** * **Diabetes Insipidus (DI):** This is a classic hallmark of stalk injury [4]. Antidiuretic hormone (ADH) is synthesized in the hypothalamus and transported via the stalk to the posterior pituitary. Damage leads to Central DI (polyuria and polydipsia) [1]. * **Thyroid Insufficiency:** Damage to the stalk prevents Thyroid Releasing Hormone (TRH) from reaching the anterior pituitary, leading to secondary hypothyroidism (low TSH and T4) [2]. * **Adrenocortical Insufficiency:** Disruption of the stalk prevents Corticotropin-Releasing Hormone (CRH) from stimulating the release of ACTH, resulting in secondary adrenal insufficiency [3]. **High-Yield Clinical Pearls for NEET-PG:** 1. **The "Stalk Effect":** While most anterior pituitary hormones decrease after stalk injury, **Prolactin levels increase**. This is because the hypothalamus normally exerts tonic *inhibition* on prolactin via dopamine; removing the stalk removes the inhibition. 2. **Triphasic Response:** Post-traumatic DI often follows a triphasic pattern: Initial polyuria (axonal shock) → Intermittent normalization (leakage of stored ADH) → Permanent DI (axonal death). 3. **Anterior vs. Posterior:** The anterior pituitary is linked via the hypophyseal portal system (vascular), while the posterior is linked via axons (neural). Stalk injury disrupts both.

Question 588: An 18-year-old girl presents with hypertension, a masculine body, and clitoromegaly. Which of the following conditions causes hyperandrogenism and hypertension?

A. 11-hydroxylase deficiency (Correct Answer)
B. 17 beta hydroxylase deficiency
C. Turner syndrome
D. Rett syndrome

Explanation: ### Explanation This clinical presentation describes **Congenital Adrenal Hyperplasia (CAH)**, specifically the **11β-hydroxylase deficiency** subtype. **1. Why 11β-hydroxylase deficiency is correct:** In this condition, the enzyme 11β-hydroxylase is deficient, blocking the conversion of 11-deoxycortisol to cortisol and 11-deoxycorticosterone (DOC) to corticosterone. This leads to: * **Hyperandrogenism:** Shunting of precursors into the androgen pathway causes virilization (masculine habitus, clitoromegaly, and hirsutism). * **Hypertension:** Unlike the more common 21-hydroxylase deficiency, there is an accumulation of **11-deoxycorticosterone (DOC)**. DOC is a potent mineralocorticoid that causes sodium retention and volume expansion, leading to hypertension and hypokalemia. **2. Why the other options are incorrect:** * **17α-hydroxylase deficiency:** While this causes hypertension (due to excess mineralocorticoids), it results in a **deficiency of sex hormones**. Patients present with delayed puberty and primary amenorrhea, not virilization. * **Turner Syndrome (45,XO):** Characterized by streak ovaries, short stature, and webbed neck. While it can be associated with coarctation of the aorta (causing hypertension), it presents with **hypoestrogenism**, not hyperandrogenism. * **Rett Syndrome:** A neurodevelopmental X-linked dominant disorder (MECP2 mutation) characterized by loss of purposeful hand movements and deceleration of head growth; it has no primary endocrine or hypertensive component. ### NEET-PG High-Yield Pearls: * **21-hydroxylase deficiency:** Most common CAH; presents with virilization + **hypotension** (salt-wasting). * **11β-hydroxylase deficiency:** Virilization + **hypertension**. * **17α-hydroxylase deficiency:** Sexual infantilism + **hypertension**. * **Mnemonic:** If the enzyme starts with **1** (11, 17), it causes **HTN**. If the enzyme ends with **1** (11, 21), it causes **virilization**.

Question 589: Which condition can cause profound hyperlipidemia?

A. Hyperinsulinemia
B. Hypothyroidism (Correct Answer)
C. Hyperparathyroidism
D. Hyperthyroidism

Explanation: **Explanation:** **Hypothyroidism** is a classic cause of secondary hyperlipidemia. Thyroid hormones play a critical role in lipid metabolism by upregulating the expression of **LDL receptors** on hepatocytes [1]. In a hypothyroid state, the decrease in thyroid hormones leads to a reduced number of LDL receptors, resulting in decreased clearance of LDL-cholesterol from the plasma. Additionally, hypothyroidism decreases the activity of **lipoprotein lipase (LPL)** and slows the oxidative metabolism of cholesterol into bile acids, leading to profound elevations in total cholesterol and LDL levels. **Analysis of Incorrect Options:** * **Hyperinsulinemia (Option A):** While insulin resistance is associated with metabolic syndrome and dyslipidemia (high triglycerides, low HDL), acute hyperinsulinemia typically promotes lipid storage and inhibits lipolysis [2]. * **Hyperparathyroidism (Option B):** This condition primarily affects calcium and phosphate homeostasis. It does not have a direct, significant impact on lipid profiles. * **Hyperthyroidism (Option D):** Excess thyroid hormone increases the expression of LDL receptors and accelerates cholesterol metabolism [1]. Consequently, hyperthyroidism typically causes **hypocholesterolemia**. **NEET-PG High-Yield Pearls:** * **Type IIb Hyperlipidemia:** Hypothyroidism most commonly presents as an elevation in LDL (Type IIa), but can also cause a mixed picture (Type IIb) with elevated VLDL. * **Statin Warning:** Always check TSH levels before starting a patient on statins. Hypothyroidism predisposes patients to **statin-induced myopathy** and rhabdomyolysis [2]. * **Other Secondary Causes:** Nephrotic syndrome (causes profound hypercholesterolemia), Obstructive jaundice, and Diabetes Mellitus.

Question 590: Doughy skin and woody induration of the tongue are seen in which of the following conditions?

A. Hyponatremia
B. Hypernatremia (Correct Answer)
C. Hypokalemia
D. Hyperkalemia

Explanation: **Explanation:** **Hypernatremia** (Option B) represents a state of hyperosmolality, typically due to a deficit in total body water relative to sodium. When serum sodium levels rise, water is drawn out of the intracellular and interstitial compartments into the intravascular space to maintain osmotic balance [1]. This profound cellular dehydration leads to characteristic physical findings: * **Doughy Skin:** Unlike the "tenting" seen in simple dehydration, the skin in hypernatremia feels thick and "doughy" due to the loss of intracellular water while maintaining some interstitial volume. * **Woody Induration of the Tongue:** The tongue becomes dry, shriveled, and firm (woody) due to extreme mucosal dehydration. **Incorrect Options:** * **Hyponatremia (A):** Typically presents with signs of cerebral edema (headache, seizures, coma) due to water moving *into* cells [1]. Skin turgor may be decreased if it is hypovolemic hyponatremia, but it does not produce the "doughy" texture. * **Hypokalemia (C) & Hyperkalemia (D):** Potassium imbalances primarily affect neuromuscular and cardiac conduction [2]. Clinical features include muscle weakness, ileus, or arrhythmias, but they do not significantly alter skin or tongue consistency. **Clinical Pearls for NEET-PG:** * **Adipsic Hypernatremia:** Often seen in elderly patients with a diminished thirst mechanism or hypothalamic lesions [2]. * **Correction Rate:** In chronic hypernatremia, the brain produces **idiogenic osmoles** to prevent shrinkage. Rapid correction can lead to **Cerebral Edema**. The goal is to lower sodium by no more than 10–12 mEq/L in 24 hours [1]. * **Key Association:** Always look for "doughy skin" in pediatric cases of severe dehydration or patients with Diabetes Insipidus.

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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