Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 121: Which of the following is NOT involved in Multiple Endocrine Neoplasia type IIA (MEN IIA)?

A. Pituitary (Correct Answer)
B. Parathyroid
C. Thyroid
D. Adrenal

Explanation: **Explanation:** Multiple Endocrine Neoplasia (MEN) syndromes are autosomal dominant conditions characterized by tumors involving two or more endocrine glands. Understanding the specific combinations is crucial for NEET-PG. **Why Pituitary is the Correct Answer:** Pituitary adenomas are a hallmark of **MEN type I (Wermer Syndrome)**, not MEN IIA. MEN I is characterized by the "3 Ps": **P**ituitary, **P**arathyroid, and **P**ancreas. Therefore, the pituitary gland is not involved in the MEN IIA spectrum. **Analysis of Incorrect Options (Involved in MEN IIA):** MEN IIA (Sipple Syndrome) is characterized by the "MPH" mnemonic: * **M - Medullary Thyroid Carcinoma (Thyroid):** This is the most common feature (nearly 100% penetrance), arising from parafollicular C-cells. * **P - Pheochromocytoma (Adrenal):** Occurs in about 50% of patients, often bilateral and located in the adrenal medulla. * **H - Hyperparathyroidism (Parathyroid):** Occurs in 20-30% of cases, usually due to parathyroid hyperplasia. **High-Yield Clinical Pearls for NEET-PG:** * **Genetics:** MEN IIA and IIB are caused by mutations in the **RET proto-oncogene** (Chromosome 10), whereas MEN I is caused by the **MEN1 gene** (Menin protein, Chromosome 11). * **MEN IIB vs. IIA:** MEN IIB includes Medullary Thyroid Carcinoma and Pheochromocytoma but lacks Parathyroid involvement. Instead, it features **Mucosal neuromas** and **Marfanoid habitus**. * **Screening:** In patients with a known RET mutation, prophylactic thyroidectomy is often recommended early in life due to the high risk of aggressive Medullary Thyroid Carcinoma.

Question 122: In congenital adrenal hyperplasia, precocious puberty in males is due to which of the following?

A. 21 alpha hydroxylase deficiency
B. 11 beta hydroxylase deficiency
C. 3 beta hydroxysteroid dehydrogenase deficiency (Correct Answer)
D. None of the above

Explanation: **Explanation:** In Congenital Adrenal Hyperplasia (CAH), precocious puberty in males is categorized as **Peripheral Precocious Puberty** (GnRH-independent). This occurs because the enzyme block leads to the shunting of steroid precursors into the androgen synthesis pathway. **Why Option C is Correct:** **3-beta hydroxysteroid dehydrogenase (3β-HSD) deficiency** is a rare form of CAH. In this condition, there is a block in the conversion of Pregnenolone to Progesterone and DHEA to Androstenedione. While it results in incomplete virilization (ambiguous genitalia) in males due to low testosterone, the accumulation of **Dehydroepiandrosterone (DHEA)**—a weak androgen—is significant. This excess DHEA can lead to premature pubarche, accelerated bone age, and signs of precocious puberty in early childhood. **Why Other Options are Incorrect:** * **Option A (21-alpha hydroxylase deficiency):** This is the most common cause of CAH (90%). While it causes virilization in females and pseudoprecocious puberty in males, the question specifically targets the mechanism where 3β-HSD is the identified answer in this specific MCQ context. (Note: In many standard texts, 21-OH and 11-β deficiency also cause precocious puberty; however, 3β-HSD is unique because it presents with DHEA excess). * **Option B (11-beta hydroxylase deficiency):** This leads to excess androgens and mineralocorticoid precursors (11-deoxycorticosterone), causing virilization and **hypertension**. **High-Yield Clinical Pearls for NEET-PG:** * **Most Common CAH:** 21-alpha hydroxylase deficiency (presents with salt-wasting and hypotension). * **CAH with Hypertension:** 11-beta hydroxylase and 17-alpha hydroxylase deficiency. * **Ambiguous Genitalia in Males:** Seen in 3β-HSD and 17-alpha hydroxylase deficiency. * **Diagnostic Marker:** 17-OH Progesterone is elevated in 21-alpha hydroxylase deficiency.

Question 123: Which of the following conditions is related to an enzyme deficiency and involves periodontal destruction around primary teeth?

A. Hypophosphatasia (Correct Answer)
B. Cyclic neutropenia
C. Juvenile periodontitis
D. Papillon-Lefevre syndrome

Explanation: **Explanation:** **Hypophosphatasia** is an inherited metabolic bone disease caused by a deficiency of the **Tissue-Nonspecific Alkaline Phosphatase (TNSALP)** enzyme. The hallmark clinical feature in children is the **premature loss of primary teeth** (specifically the incisors) before age 4. This occurs due to defective cementum formation, which prevents the periodontal ligament from attaching the tooth to the alveolar bone, leading to periodontal destruction and exfoliation without significant root resorption. **Analysis of Incorrect Options:** * **Cyclic Neutropenia (B):** While it causes periodic oral ulcers and periodontal bone loss due to a drop in neutrophil counts, it is a hematological disorder, not an enzyme deficiency. * **Juvenile Periodontitis (C):** Now termed Aggressive Periodontitis, this is primarily an inflammatory/infectious condition associated with *Aggregatibacter actinomycetemcomitans*, not an enzyme defect. * **Papillon-Lefevre Syndrome (D):** This involves severe periodontitis and palmoplantar keratoderma. While it is caused by a mutation in the *Cathepsin C* gene (a protease), the classic NEET-PG presentation for "enzyme deficiency with early tooth loss" specifically points toward Hypophosphatasia due to the diagnostic marker of low serum alkaline phosphatase. **Clinical Pearls for NEET-PG:** * **Diagnostic Marker:** Low serum Alkaline Phosphatase (ALP) levels and elevated urinary phosphoethanolamine. * **Radiology:** "Beaten copper" appearance of the skull and "bowing" of long bones (Rickets-like features). * **Key Differentiator:** In Hypophosphatasia, teeth fall out with **intact roots**, unlike normal exfoliation where roots are resorbed.

Question 124: A 2-month-old infant presents with generalized muscle weakness and a "floppy infant" appearance. Additional features include macroglossia, feeding difficulty, hepatomegaly, and hypertrophic cardiomyopathy. What is the diagnosis?

A. Type I Glycogen Storage Disease (GSD)
B. Type II Glycogen Storage Disease (GSD) (Correct Answer)
C. Type III Glycogen Storage Disease (GSD)
D. Type IV Glycogen Storage Disease (GSD)

Explanation: **Explanation:** The clinical presentation of a "floppy infant" (hypotonia) combined with **macroglossia** and **hypertrophic cardiomyopathy** is classic for **Type II Glycogen Storage Disease (Pompe Disease)**. Unlike other GSDs, Pompe disease is a **lysosomal storage disorder** caused by a deficiency of **Acid Alpha-Glucosidase (Acid Maltase)**. This enzyme is responsible for breaking down glycogen within lysosomes. Its deficiency leads to massive accumulation of glycogen in cardiac, skeletal, and smooth muscle cells. The involvement of the heart (cardiomegaly/cardiomyopathy) is the pathognomonic feature that distinguishes it from other GSDs in infancy. **Analysis of Incorrect Options:** * **Type I (von Gierke):** Characterized by severe fasting hypoglycemia, lactic acidosis, and hyperuricemia. It involves the liver and kidneys, but **not the muscles or heart**. * **Type III (Cori):** Similar to Type I but milder, with normal lactate levels. While it can involve muscles, it does not typically present with the severe infantile cardiomyopathy seen in Pompe. * **Type IV (Andersen):** Presents primarily with **liver cirrhosis** and failure in early childhood due to the accumulation of abnormal glycogen (amylopectin). **NEET-PG High-Yield Pearls:** * **Pompe Disease** is the only GSD that is also a **Lysosomal Storage Disease**. * **ECG Finding:** Characteristically shows **giant QRS complexes** and a short PR interval. * **Biopsy:** Shows PAS-positive material within lysosomes. * **Treatment:** Enzyme Replacement Therapy (Alglucosidase alfa).

Question 125: Which of the following conditions commonly presents with a large tongue?

A. Turner syndrome
B. Treacher Collins syndrome
C. Hypothyroidism (Correct Answer)
D. Congenital syphilis

Explanation: **Explanation:** **Macroglossia (a large tongue)** is a classic clinical hallmark of **Congenital Hypothyroidism**. The underlying mechanism involves the accumulation of **glycosaminoglycans** (such as hyaluronic acid) within the interstitial tissues of the tongue. This occurs due to a decreased metabolic rate and altered protein metabolism, leading to a thickened, protruding tongue that can cause feeding difficulties and noisy breathing (stridor). **Analysis of Incorrect Options:** * **Turner Syndrome (45, XO):** Characterized by a high-arched palate, webbed neck, and short stature, but not macroglossia. * **Treacher Collins Syndrome:** A craniofacial disorder characterized by mandibular hypoplasia (micrognathia) and malformed ears. The tongue is of normal size, but the small jaw may make it appear prominent or cause it to fall back (glossoptosis). * **Congenital Syphilis:** Presents with features like Hutchinson’s teeth, mulberry molars, and saddle nose, but macroglossia is not a feature. **High-Yield Clinical Pearls for NEET-PG:** * **Differential Diagnosis of Macroglossia:** Remember the mnemonic **"BIG TONGUE"**: **B**eckwith-Wiedemann Syndrome (most common overgrowth syndrome), **I**diopathic, **G**lycogen storage disease (Pompe disease), **T**risomy 21 (Down Syndrome), **O**bstruction (Hemangioma/Lymphangioma), **N**eoplasia, **G**rave’s disease/Hypothyroidism, **U**nusual (Amyloidosis), **E**ndocrine (Acromegaly). * **Congenital Hypothyroidism:** Also presents with a large posterior fontanelle, prolonged physiological jaundice, umbilical hernia, and constipation. It is the most common preventable cause of intellectual disability. * **Screening:** The best time for neonatal screening (TSH) is after 48–72 hours of birth to avoid the physiological TSH surge.

Question 126: Which of the following biochemical findings are seen in Rickets?

A. Increased Alkaline Phosphatase (ALP)
B. Hypophosphatemia
C. Hyperphosphaturia
D. All of the above (Correct Answer)

Explanation: **Explanation:** The biochemical hallmark of Rickets (specifically Vitamin D deficiency rickets) is driven by the body's attempt to maintain calcium homeostasis through **Secondary Hyperparathyroidism**. 1. **Increased Alkaline Phosphatase (ALP):** This is the **earliest and most sensitive** biochemical marker of rickets. Vitamin D deficiency leads to poor mineralization of the osteoid. To compensate, osteoblastic activity increases significantly, releasing high levels of ALP into the bloodstream. 2. **Hypophosphatemia:** Low Vitamin D levels lead to decreased intestinal calcium absorption, causing a drop in serum calcium. This triggers the Parathyroid hormone (PTH). PTH acts on the kidneys to decrease phosphate reabsorption in the proximal tubules, leading to low serum phosphate. 3. **Hyperphosphaturia:** As a direct result of the PTH-mediated inhibition of the sodium-phosphate cotransporter in the renal tubules, phosphate is "wasted" in the urine. **Why "All of the above" is correct:** The sequence is: ↓Vitamin D → ↓Serum Calcium → ↑PTH → **↑Urinary Phosphate (Hyperphosphaturia)** → **↓Serum Phosphate (Hypophosphatemia)**. Simultaneously, the bone's compensatory response leads to **↑ALP**. **Clinical Pearls for NEET-PG:** * **Serum Calcium:** Usually remains **normal or low-normal** in early stages due to PTH compensation; it only drops significantly when compensatory mechanisms fail. * **Radiological sign:** The earliest sign is the loss of the provisional zone of calcification at the metaphysis. * **Vitamin D levels:** 25-hydroxyvitamin D [25(OH)D] is the best indicator of nutritional status, while 1,25(OH)₂D may be normal or even elevated due to high PTH.

Question 127: Which of the following is NOT a characteristic of Mauriac's syndrome?

A. Diabetes
B. Obesity
C. Dwarfism
D. Cardiomegaly (Correct Answer)

Explanation: **Explanation:** **Mauriac’s Syndrome** is a rare complication of Type 1 Diabetes Mellitus, typically seen in children and adolescents with poorly controlled glycemic levels. It is characterized by a classic tetrad of clinical features. **Why Cardiomegaly is the correct answer:** Cardiomegaly is **not** a feature of Mauriac’s Syndrome. While chronic diabetes can lead to long-term cardiovascular complications in adults, the specific pediatric presentation of Mauriac’s Syndrome involves metabolic and growth disturbances rather than structural heart enlargement. **Analysis of incorrect options:** * **A. Diabetes:** Poorly controlled Type 1 Diabetes is the prerequisite for this syndrome. The underlying pathophysiology involves periods of hyperglycemia followed by supraphysiological insulin doses, leading to glycogen deposition. * **B. Obesity:** Patients typically present with **cushingoid features**, including a "moon face" and truncal obesity (fat redistribution), despite having a low BMI or appearing wasted in the extremities. * **C. Dwarfism:** Growth failure or **stunted growth** is a hallmark. This occurs due to a combination of relative insulin deficiency, low IGF-1 levels, and delayed bone age. **Clinical Pearls for NEET-PG:** * **The Tetrad:** 1. Poorly controlled Type 1 Diabetes, 2. Growth failure (Dwarfism), 3. Delayed puberty, and 4. **Hepatomegaly** (due to glycogenosis/fatty liver). * **Key Diagnostic Sign:** Massive hepatomegaly is the most striking feature, caused by glycogen trapping in hepatocytes. * **Reversibility:** Most features, including growth and liver size, can improve significantly with optimized glycemic control and intensive insulin therapy.

Question 128: Which of the following is NOT a feature of Hypothyroidism?

A. Delayed dentition
B. Widened fontanelle
C. Distended abdomen
D. All of the above are features of Hypothyroidism (Correct Answer)

Explanation: **Explanation:** Congenital hypothyroidism (CH) is one of the most common treatable causes of intellectual disability. The clinical features of hypothyroidism in children are primarily due to a generalized slowing of metabolic processes and delayed skeletal maturation. **Why the correct answer is D:** All the listed options are classic clinical manifestations of hypothyroidism: * **Delayed Dentition:** Thyroid hormones are essential for bone maturation and tooth eruption. Deficiency leads to delayed appearance of deciduous and permanent teeth. * **Widened Fontanelle:** Hypothyroidism causes delayed ossification of the skull bones, leading to large anterior and posterior fontanelles. A posterior fontanelle >0.5 cm is a highly sensitive early sign of CH. * **Distended Abdomen:** This occurs due to generalized hypotonia (floppy baby) and slowed gastrointestinal motility, which often presents as constipation and an umbilical hernia. **Why other options are incorrect:** Options A, B, and C are incorrect because they are all established features of the disease. Since the question asks which is *NOT* a feature, and all are present, "All of the above" is the only logically sound choice. **High-Yield Clinical Pearls for NEET-PG:** * **Early Signs:** Prolonged physiological jaundice (most common early sign), poor feeding, and lethargy. * **Classic Triad:** Coarse facies, macroglossia (large tongue), and umbilical hernia. * **Skeletal Age:** Delayed bone age is a hallmark; look for the absence of the distal femoral epiphysis at birth. * **Screening:** The best time for neonatal screening (TSH) is between **48–72 hours** of life to avoid the physiological TSH surge. * **Treatment:** Levothyroxine is the drug of choice; the goal is to maintain T4 in the upper half of the normal range to ensure optimal brain development.

Question 129: Pseudohermaphroditism in a female child is most commonly due to which of the following?

A. 21-hydroxylase deficiency (Correct Answer)
B. 17-hydroxylase deficiency
C. 11-hydroxylase deficiency
D. 3-hydroxylase deficiency

Explanation: **Explanation:** The most common cause of female pseudohermaphroditism (virilized female/46,XX DSD) is **Congenital Adrenal Hyperplasia (CAH)**, and among its variants, **21-hydroxylase deficiency** accounts for approximately **90-95% of cases**. **Why 21-hydroxylase deficiency is correct:** In this condition, a block in the conversion of progesterone to deoxycorticosterone and 17-OH progesterone to 11-deoxycortisol leads to decreased cortisol and aldosterone. The resulting increase in ACTH (due to lack of negative feedback) shunts steroid precursors into the **androgen pathway**. High levels of testosterone and androstenedione cause virilization of the female fetus (ambiguous genitalia, clitoromegaly), while the internal female organs (uterus, ovaries) remain normal as they are not androgen-dependent. **Analysis of Incorrect Options:** * **11-hydroxylase deficiency:** This is the second most common cause (approx. 5-8%). While it also causes virilization, it is distinguished by the presence of **hypertension** (due to accumulation of 11-deoxycorticosterone, a mineralocorticoid). * **17-hydroxylase deficiency:** This leads to a decrease in both androgens and cortisol. It causes **delayed puberty** in females and **undervirilization (pseudohermaphroditism) in males**, not females. * **3-beta-hydroxysteroid dehydrogenase deficiency:** A rare form that causes a block early in the pathway. It results in incomplete virilization in females and undervirilization in males. **High-Yield Clinical Pearls for NEET-PG:** * **Most common presentation:** Salt-wasting crisis (hyponatremia, hyperkalemia, hypotension) in the first 2 weeks of life. * **Diagnostic Marker:** Elevated serum **17-hydroxyprogesterone (17-OHP)**. * **Karyotype:** Always 46,XX in female pseudohermaphroditism. * **Management:** Glucocorticoid (Hydrocortisone) and Mineralocorticoid (Fludrocortisone) replacement.

Question 130: A five-year-old boy presents with precocious puberty and a blood pressure of 130/80 mm Hg. Estimation of which of the following will help in the diagnosis?

A. 17-Hydroxyprogesterone
B. Cortisol
C. Deoxycortisol (Correct Answer)
D. Aldosterone

Explanation: The clinical presentation of **precocious puberty** (virilization) combined with **hypertension** in a young child is the classic hallmark of **11β-hydroxylase deficiency**, the second most common cause of Congenital Adrenal Hyperplasia (CAH). ### Why Deoxycortisol is Correct In 11β-hydroxylase deficiency, the conversion of **11-deoxycortisol to cortisol** and **11-deoxycorticosterone (DOC) to corticosterone** is blocked. This leads to: 1. **Excess Androgens:** Shunting of precursors toward the androgen pathway causes precocious puberty/virilization. 2. **Hypertension:** The accumulation of **11-deoxycorticosterone (DOC)**, a potent mineralocorticoid, causes salt and water retention, leading to high blood pressure. 3. **Diagnosis:** Elevated levels of **11-deoxycortisol** in the blood are diagnostic for this specific enzyme defect. ### Why Other Options are Incorrect * **17-Hydroxyprogesterone (17-OHP):** This is the screening marker for **21-hydroxylase deficiency**. While 21-hydroxylase deficiency also causes precocious puberty, it is typically associated with **hypotension** (salt-wasting) rather than hypertension. * **Cortisol:** Cortisol levels are typically low or low-normal in all forms of CAH due to the enzymatic blocks; it is not a specific diagnostic marker for the subtype. * **Aldosterone:** In 11β-hydroxylase deficiency, aldosterone levels are actually **low** because the excess DOC suppresses the Renin-Angiotensin-Aldosterone System (RAAS). ### NEET-PG High-Yield Pearls * **21-Hydroxylase Deficiency:** Most common CAH; Virilization + **Hypotension** (Salt-wasting). * **11β-Hydroxylase Deficiency:** Virilization + **Hypertension**. * **17α-Hydroxylase Deficiency:** **Hypertension** + Delayed Puberty (No virilization; decreased sex hormones). * **Mnemonic:** If the enzyme starts with **1** (11, 17), it causes **Hypertension**. If the enzyme ends with **1** (11, 21), it causes **Virilization**.

Practice by Chapter

Disorders of Growth

Practice Questions

Thyroid Disorders

Practice Questions

Disorders of Puberty

Practice Questions

Adrenal Disorders

Practice Questions

Diabetes Mellitus in Children

Practice Questions

Disorders of Calcium and Phosphate Metabolism

Practice Questions

Disorders of Sexual Development

Practice Questions

Hypoglycemia

Practice Questions

Obesity and Metabolic Syndrome

Practice Questions

Pituitary Disorders

Practice Questions

Multiple Endocrine Neoplasia Syndromes

Practice Questions

Endocrine Emergencies

Practice Questions

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