Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 131: A child presents with severe intellectual disability, a pot-bellied appearance, pale complexion, puffy face, and an enlarged tongue. Dietary deficiency of which of the following substances can lead to this clinical presentation?

A. Calcium
B. Iodine (Correct Answer)
C. Iron
D. Magnesium

Explanation: ### Explanation The clinical presentation described—**severe intellectual disability, pot-bellied appearance, puffy face (myxedema), and macroglossia (enlarged tongue)**—is a classic description of **Congenital Hypothyroidism** (formerly known as Cretinism). **1. Why Iodine is Correct:** Iodine is an essential trace element required for the synthesis of thyroid hormones (T3 and T4). In regions with soil deficient in iodine (endemic areas), maternal iodine deficiency leads to inadequate thyroid hormone production in the fetus and neonate. Since thyroid hormones are critical for **neurogenesis and skeletal maturation**, a deficiency during these critical periods results in irreversible intellectual disability and stunted growth. The "pot-belly" is often due to hypotonia and associated umbilical hernias, while the puffy face and large tongue result from the accumulation of glycosaminoglycans in the dermis. **2. Why Other Options are Incorrect:** * **Calcium:** Deficiency leads to rickets (skeletal deformities) or tetany, but not intellectual disability or macroglossia. * **Iron:** Deficiency causes microcytic hypochromic anemia, leading to pallor and fatigue, but does not cause the structural or developmental changes seen here. * **Magnesium:** Deficiency typically presents with neuromuscular irritability (tremors, seizures) or cardiac arrhythmias, not a hypothyroid phenotype. **3. NEET-PG High-Yield Pearls:** * **Most common cause worldwide:** Iodine deficiency (Endemic Cretinism). * **Most common cause in developed/non-endemic areas:** Thyroid dysgenesis (Ectopic thyroid is the most common subtype). * **Screening:** Neonatal screening is done via **heel prick** (TSH levels) on day 3–5 of life. * **Early Sign:** Prolonged physiological jaundice is often the earliest clinical sign of congenital hypothyroidism. * **Radiology:** Absence of the **distal femoral epiphysis** at birth is a sign of intrauterine hypothyroidism (delayed bone age).

Question 132: What is the treatment for a case of virilizing adrenal hyperplasia?

A. Estrogens
B. Antiandrogens
C. ACTH
D. None of these (Correct Answer)

Explanation: **Explanation:** The clinical scenario describes **Congenital Adrenal Hyperplasia (CAH)**, most commonly caused by **21-hydroxylase deficiency**. In this condition, a block in the cortisol synthesis pathway leads to a lack of negative feedback on the pituitary, resulting in **excessive ACTH secretion**. This overstimulates the adrenal cortex, shunting precursors toward the androgen pathway, causing virilization. **Why "None of these" is correct:** The primary goal of treatment is to replace the deficient hormone (Cortisol) and suppress the excess ACTH. The treatment of choice is **Glucocorticoids (e.g., Hydrocortisone)**. By providing exogenous cortisol, the feedback loop is restored, ACTH levels drop, and the stimulus for adrenal androgen production is removed. In salt-wasting forms, **Mineralocorticoids (Fludrocortisone)** are also required. **Analysis of Incorrect Options:** * **A. Estrogens:** These do not address the underlying enzyme deficiency or the ACTH excess. * **B. Antiandrogens:** While they may block peripheral action, they do not treat the life-threatening cortisol/aldosterone deficiency. * **C. ACTH:** Administering ACTH would worsen the condition by further stimulating the adrenal gland to produce more androgens. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause:** 21-hydroxylase deficiency (90% of cases). * **Diagnostic Marker:** Elevated **17-hydroxyprogesterone (17-OHP)** levels. * **Clinical Presentation:** Ambiguous genitalia in females; salt-wasting crisis (hyponatremia, hyperkalemia, hypotension) in the first 2 weeks of life. * **Karyotype:** In a virilized female (Prader staging), the karyotype remains **46, XX**.

Question 133: All of the following may be causes of precocious puberty in girls except?

A. Hypothalamic hamartoma
B. McCune-Albright syndrome
C. Granulosa cell tumor of ovary
D. Congenital 21-hydroxylase deficiency (Correct Answer)

Explanation: **Explanation:** The core concept in this question is the distinction between **Precocious Puberty** (development of secondary sexual characteristics) and **Precocious Virilization**. **Why D is the correct answer:** Congenital Adrenal Hyperplasia (CAH) due to **21-hydroxylase deficiency** leads to an excess of adrenal androgens. In girls, this causes **virilization** (clitoromegaly, pubic hair, acne, and accelerated bone age) but **not** true precocious puberty. Crucially, androgens do not cause breast development (the hallmark of female puberty); in fact, they can antagonize estrogen's effects. Therefore, CAH in girls presents as "isosexual precocious pseudopuberty" only in terms of hair growth, but it lacks the breast development required for the clinical definition of precocious puberty. **Why the other options are incorrect:** * **A. Hypothalamic hamartoma:** The most common organic cause of **Central Precocious Puberty (CPP)**. It acts as an ectopic GnRH pulse generator, activating the entire HPO axis. * **B. McCune-Albright Syndrome:** A classic cause of **Peripheral Precocious Puberty**. It involves a G-protein mutation leading to autonomous ovarian estrogen production, typically presenting with the triad of precocious puberty, café-au-lait spots, and polyostotic fibrous dysplasia. * **C. Granulosa cell tumor:** An estrogen-secreting ovarian tumor. It causes peripheral precocious puberty characterized by rapid breast development and vaginal bleeding. **High-Yield Clinical Pearls for NEET-PG:** * **Definition:** Precocious puberty is defined as the onset of secondary sexual characteristics before **8 years** in girls and **9 years** in boys. * **The "Rule of Thumb":** In girls, the first sign of true puberty is **Thelarche** (breast budding). In boys, it is **Testicular enlargement** (>4ml). * **CAH in Boys:** Unlike girls, 21-hydroxylase deficiency **can** cause precocious pseudopuberty in boys (early phallic enlargement) because the adrenal androgens mimic the male sexual profile.

Question 134: Which of the following represents the triad of signs and symptoms of osteogenesis imperfecta?

A. Blue sclera, sparse hair, anhydrosis
B. Enlarged hands, feet, maxilla, and mandible
C. Blue sclera, brittle bones, opalescent dentin (Correct Answer)
D. Blue sclera, arachnodactyly, brittle bones

Explanation: **Explanation:** **Osteogenesis Imperfecta (OI)**, also known as "Brittle Bone Disease," is a heterogeneous group of genetic disorders primarily caused by mutations in the **COL1A1 and COL1A2 genes**, leading to a defect in the synthesis of **Type I Collagen**. Since Type I collagen is a major structural component of bones, sclera, and teeth, the clinical manifestations are widespread. 1. **Why Option C is correct:** The classic clinical triad includes: * **Brittle Bones:** Recurrent fractures with minimal trauma due to skeletal fragility. * **Blue Sclera:** Thinning of the scleral collagen allows the underlying choroidal veins to show through. * **Opalescent Dentin (Dentinogenesis Imperfecta):** Teeth appear brownish-blue or translucent due to defective dentin. * *Note:* Hearing loss (conductive or sensorineural) is also a common feature often included in the expanded clinical picture. 2. **Why other options are incorrect:** * **Option A:** Sparse hair and anhidrosis are characteristic of **Hypohidrotic Ectodermal Dysplasia**. * **Option B:** Enlargement of extremities and facial bones (maxilla/mandible) describes **Acromegaly**. * **Option D:** Arachnodactyly (long, slender fingers) is a hallmark of **Marfan Syndrome**. While Marfan may involve the sclera (ectopia lentis), it does not typically present with brittle bones. **High-Yield Clinical Pearls for NEET-PG:** * **Inheritance:** Most common types (Type I and IV) are Autosomal Dominant. Type II is the most severe (lethal in the perinatal period). * **Radiology:** Look for "Popcorn calcifications" at the metaphysis and "Wormian bones" (sutural bones) on skull X-ray. * **Management:** **Bisphosphonates** (e.g., Pamidronate) are the mainstay of medical treatment to increase bone mineral density and reduce fractures. * **Differential Diagnosis:** Always rule out **Child Abuse (Non-Accidental Injury)** in infants presenting with multiple fractures.

Question 135: What is the inheritance pattern of congenital adrenal hyperplasia?

A. Autosomal Dominant (AD)
B. Autosomal Recessive (AR) (Correct Answer)
C. X-linked Dominant (XD)
D. X-linked Recessive (XR)

Explanation: **Explanation:** **Congenital Adrenal Hyperplasia (CAH)** is a group of inherited disorders characterized by a deficiency in one of the enzymes required for cortisol synthesis in the adrenal cortex. 1. **Why Autosomal Recessive (AR) is correct:** CAH follows an **Autosomal Recessive** inheritance pattern. This means an affected individual must inherit two mutated alleles (one from each parent). The parents are typically asymptomatic carriers. The most common cause (95% of cases) is a deficiency of the enzyme **21-hydroxylase**, encoded by the *CYP21A2* gene located on Chromosome 6. Because it is an enzymatic defect, it follows the general rule in genetics that most inborn errors of metabolism are inherited in an AR fashion. 2. **Why other options are incorrect:** * **Autosomal Dominant (AD):** AD disorders usually involve structural proteins or receptors (e.g., Marfan syndrome). CAH involves enzyme deficiencies, which rarely manifest in a heterozygous state. * **X-linked (XD/XR):** CAH affects males and females equally and involves genes located on autosomes (like Chromosome 6 or 11), ruling out sex-linked inheritance. **High-Yield Clinical Pearls for NEET-PG:** * **Most Common Enzyme Deficiency:** 21-hydroxylase deficiency (leads to increased 17-OH Progesterone). * **Classic Presentation:** Salt-wasting (hyponatremia, hyperkalemia, hypotension) and virilization (ambiguous genitalia in females). * **Diagnostic Marker:** Elevated serum **17-hydroxyprogesterone (17-OHP)**. * **Treatment:** Glucocorticoids (to suppress ACTH and replace cortisol) and Mineralocorticoids (Fludrocortisone for salt-wasters). * **Screening:** Newborn screening for CAH is now part of many national programs using the heel-prick test for 17-OHP.

Question 136: A 15-year-old girl presents with short stature, neck webbing, and sexual infantilism. She is also found to have coarctation of the aorta. A chromosomal analysis is likely to demonstrate which of the following?

A. Mutation at chromosome 15q21.1
B. Trisomy 21
C. XO karyotype (Correct Answer)
D. Defect at chromosome 4p16

Explanation: ### Explanation **Correct Answer: C. XO karyotype** The clinical triad of **short stature, neck webbing (pterygium colli), and sexual infantilism** (due to streak ovaries/gonadal dysgenesis) in a phenotypic female is the classic presentation of **Turner Syndrome**. The presence of **coarctation of the aorta** (the most common cardiovascular malformation in Turner syndrome, occurring in ~15-20% of cases) further confirms the diagnosis. Turner syndrome is most commonly caused by **45,X monosomy** (XO karyotype), resulting from the loss of part or all of an X chromosome. **Analysis of Incorrect Options:** * **A. Mutation at chromosome 15q21.1:** This is associated with **Marfan Syndrome** (FBN1 gene). While Marfan patients have cardiac issues (aortic root dilation), they typically present with tall stature and arachnodactyly, the opposite of this patient's phenotype. * **B. Trisomy 21:** This causes **Down Syndrome**. While associated with cardiac defects (most commonly Endocardial Cushion Defects/AVSD), it presents with distinct facies, intellectual disability, and hypotonia rather than sexual infantilism and neck webbing. * **D. Defect at chromosome 4p16:** This is the locus for **Wolf-Hirschhorn Syndrome**, characterized by "Greek warrior helmet" facies, microcephaly, and severe developmental delay. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of primary amenorrhea:** Turner Syndrome. * **Skeletal finding:** Positive **Archibald sign** (short 4th metacarpal) and Madelung deformity. * **Renal association:** **Horseshoe kidney** is the most common renal anomaly. * **Lymphedema:** Newborns often present with lymphedema of hands and feet and cystic hygroma. * **Genetics:** 50% are 45,X; others are mosaics (e.g., 45,X/46,XX) or structural abnormalities (isochromosome Xq). Mosaics have a higher risk of gonadoblastoma if a Y chromosome fragment is present.

Question 137: What is the most common cause of delayed puberty in males?

A. Kallmann syndrome
B. Klinefelter syndrome
C. Constitutional delay (Correct Answer)
D. Prader-Willi syndrome

Explanation: **Explanation:** **Constitutional Delay of Growth and Puberty (CDGP)** is the most common cause of delayed puberty in both males and females, accounting for approximately 60–80% of cases. It is essentially a "late bloomer" phenomenon where the onset of puberty is delayed, but the sequence of development is normal. It is often associated with a positive family history and a characteristic delay in **bone age** compared to chronological age. These individuals eventually achieve normal adult height and full sexual maturation without intervention. **Analysis of Incorrect Options:** * **Kallmann Syndrome:** A form of hypogonadotropic hypogonadism (low FSH/LH) associated with anosmia (loss of smell). While a significant cause, it is much rarer than CDGP. * **Klinefelter Syndrome (47, XXY):** The most common cause of **primary hypogonadism** (hypergonadotropic hypogonadism). While it causes small testes and infertility, it usually presents with a normal or slightly delayed *onset* of puberty, but failure of completion. * **Prader-Willi Syndrome:** A genetic disorder (deletion on paternal chromosome 15) characterized by infantile hypotonia, hyperphagia/obesity, and hypogonadotropic hypogonadism. It is a rare syndromic cause of delayed puberty. **Clinical Pearls for NEET-PG:** * **Definition:** Delayed puberty in males is defined as the absence of testicular enlargement (**<4 mL volume** or <2.5 cm length) by **14 years** of age. * **Bone Age:** In CDGP, bone age is delayed and consistent with the height age, whereas in permanent hypogonadism, the discrepancy may be more pronounced. * **First Sign of Puberty (Males):** Testicular enlargement (due to FSH stimulating seminiferous tubules). * **Management:** Reassurance is the mainstay for CDGP. Short-term, low-dose testosterone may be used to "jumpstart" puberty if there is significant psychological distress.

Question 138: A 2-year-old child presented with diarrhea and failure to thrive. Blood examination shows Na = 122 mEq/L, K = 6 mEq/L. The child is most probably suffering from which of the following conditions?

A. Bartter syndrome
B. 21-hydroxylase deficiency (Correct Answer)
C. 11-β-hydroxylase deficiency
D. 17-α-hydroxylase deficiency

Explanation: ### Explanation The clinical presentation of a 2-year-old with **hyponatremia (122 mEq/L)** and **hyperkalemia (6 mEq/L)**, accompanied by failure to thrive and diarrhea (often representing a "salt-wasting crisis"), is classic for **Congenital Adrenal Hyperplasia (CAH)**, specifically the salt-wasting form. **1. Why 21-Hydroxylase Deficiency is Correct:** This is the most common cause of CAH (>90% of cases). The enzyme deficiency blocks the conversion of progesterone to deoxycorticosterone (mineralocorticoid pathway) and 17-OH progesterone to 11-deoxycortisol (glucocorticoid pathway). * **Mineralocorticoid deficiency (Aldosterone ↓):** Leads to salt wasting, resulting in **hyponatremia**, **hyperkalemia**, and metabolic acidosis. * **Glucocorticoid deficiency (Cortisol ↓):** Leads to hypoglycemia and poor stress response. * **Androgen excess:** Excess precursors are shunted toward testosterone production, causing virilization in females and precocious puberty in males. **2. Why Incorrect Options are Wrong:** * **Bartter Syndrome:** Characterized by defective salt reabsorption in the thick ascending limb of Henle. It presents with **hypokalemia** and metabolic alkalosis, not hyperkalemia. * **11-β-hydroxylase Deficiency:** While it causes cortisol deficiency and androgen excess, it leads to the buildup of 11-deoxycorticoserone (DOC), a potent mineralocorticoid. This causes **hypertension** and **hypokalemia**. * **17-α-hydroxylase Deficiency:** Results in increased mineralocorticoids (DOC) but decreased sex hormones. It presents with **hypertension**, **hypokalemia**, and delayed puberty/sexual infantilism. **3. NEET-PG Clinical Pearls:** * **Gold Standard Diagnosis:** Elevated **17-hydroxyprogesterone (17-OHP)** levels. * **Classic Sign:** Ambiguous genitalia in newborn females; "Salt-wasting crisis" (vomiting, dehydration, shock) usually occurs in the 2nd week of life. * **Treatment:** Glucocorticoid (Hydrocortisone) and Mineralocorticoid (Fludrocortisone) replacement.

Question 139: Clinical manifestations of hoarse cry, umbilical hernia, hypotonia, mottling of skin, and lethargy, with prolonged jaundice, are seen in which condition?

A. Gaucher's disease
B. Mucopolysaccharidosis
C. Growth hormone deficiency
D. Congenital hypothyroidism (Correct Answer)

Explanation: **Explanation:** The clinical presentation described is a classic textbook case of **Congenital Hypothyroidism (CH)**. In the neonatal period, most infants appear normal at birth due to the transplacental transfer of maternal thyroid hormones. However, as these levels decline, symptoms emerge. * **Why Congenital Hypothyroidism is correct:** Thyroid hormones are essential for metabolic processes and neurological development. Deficiency leads to: * **Metabolic slowing:** Lethargy, poor feeding, and constipation. * **Structural changes:** Myxedematous infiltration causes a **hoarse cry** and macroglossia. * **Developmental defects:** Weakness of the abdominal wall leads to **umbilical hernia**, and low muscle tone results in **hypotonia**. * **Circulatory signs:** **Mottling of the skin** (cutis marmorata) and cold extremities due to poor peripheral circulation. * **Jaundice:** Prolonged unconjugated hyperbilirubinemia occurs due to delayed maturation of hepatic glucuronyl transferase. **Analysis of Incorrect Options:** * **Gaucher’s Disease:** A lysosomal storage disorder characterized by hepatosplenomegaly and bone pain, but it does not typically present with a hoarse cry or umbilical hernia in the neonatal period. * **Mucopolysaccharidosis (MPS):** While MPS (like Hurler syndrome) features coarse facies and umbilical hernias, these features usually manifest later in infancy (6–12 months), not as neonatal prolonged jaundice. * **Growth Hormone Deficiency:** Typically presents with hypoglycemia and micropenis in neonates; it does not cause a hoarse cry or umbilical hernia. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause:** Dysgenesis (Aplasia/Hypoplasia/Ectopy) of the thyroid gland. * **Earliest Sign:** Prolonged physiological jaundice. * **Most Sensitive Screening Test:** Serum TSH (measured via heel prick at 48–72 hours of life). * **Radiological Sign:** Absence of distal femoral epiphysis (normally present at birth) indicates intrauterine hypothyroidism.

Question 140: A 7-year-old girl presents with short stature. Examination reveals cubitus valgus, a shield-shaped chest with widely spaced nipples, a webbed neck, and a short 4th metacarpal. What is the most likely clinical diagnosis?

A. Klinefelter's syndrome
B. Edward Syndrome
C. Patau syndrome
D. Turner syndrome (Correct Answer)

Explanation: **Explanation:** The clinical presentation described is a classic textbook case of **Turner Syndrome (45, XO)**. This condition is the most common sex chromosome abnormality in females, characterized by the complete or partial absence of one X chromosome. **Why Turner Syndrome is correct:** The patient exhibits the hallmark phenotypic features of Turner Syndrome: * **Skeletal findings:** Short stature (most consistent feature), **cubitus valgus** (increased carrying angle of the arm), and a **short 4th metacarpal** (Archibald’s sign). * **Dermatological/Soft tissue:** **Webbed neck** (due to cystic hygroma in utero). * **Thoracic findings:** **Shield-shaped chest** with widely spaced nipples. * **Other common associations:** Bicuspid aortic valve, coarctation of the aorta, and streak ovaries leading to primary amenorrhea. **Why the other options are incorrect:** * **Klinefelter’s Syndrome (47, XXY):** Affects males. Characterized by tall stature, gynecomastia, small firm testes, and infertility. * **Edward Syndrome (Trisomy 18):** Presents with severe intellectual disability, micrognathia, low-set ears, and characteristic **clenched fists** with overlapping fingers. Most do not survive past infancy. * **Patau Syndrome (Trisomy 13):** Presents with midline defects such as cleft lip/palate, holoprosencephaly, polydactyly, and **microphthalmia**. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cardiac defect:** Bicuspid aortic valve (most common overall); Coarctation of the aorta (most specific). * **Renal anomaly:** Horseshoe kidney. * **Karyotype:** 45, XO is most common (50%), but mosaicism (45,X/46,XX) carries a higher risk of gonadoblastoma if Y chromosome material is present. * **Gold Standard Diagnosis:** Chromosomal analysis (Karyotyping).

Practice by Chapter

Disorders of Growth

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Thyroid Disorders

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Disorders of Puberty

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Adrenal Disorders

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Diabetes Mellitus in Children

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Disorders of Calcium and Phosphate Metabolism

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Disorders of Sexual Development

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Hypoglycemia

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Obesity and Metabolic Syndrome

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Pituitary Disorders

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Multiple Endocrine Neoplasia Syndromes

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Endocrine Emergencies

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