Endocrinology — MCQs

The parents of a 4-week-old girl complain that their baby is apathetic and sluggish. On physical examination, the child's abdomen is large and exhibits an umbilical hernia. The skin is pale and cold, and the temperature is 35°C (95°F). Which of the following provides a plausible explanation for the signs and symptoms of this child?

Q55Medium

Which statin is indicated for an 8-year-old child diagnosed with heterozygous familial hypercholesterolemia?

Q56Medium

A child underwent bilateral adrenalectomy. Later, the child developed headache, visual field defect, and hyperpigmentation of the skin. What is the most probable diagnosis?

Q57Medium

What is the most common presentation of hypoparathyroidism beyond the neonatal period?

Q58Medium

Which of the following is NOT a known cause of precocious puberty?

Q59Easy

Precocious puberty is seen in which of the following conditions?

Q60Medium

Male pseudohermaphroditism is seen in which of the following conditions?

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 51: A newborn baby presents with tachycardia, hypotension, and irritability. USG revealed normal ovaries, and the karyotype is 46,XX. Which of the following biochemical abnormalities is not typically seen in this clinical scenario?

A. Hyperglycemia (Correct Answer)
B. Hypoglycemia
C. Hyponatremia
D. Hyperkalemia

Explanation: **Explanation:** The clinical presentation of a newborn with tachycardia, hypotension (signs of shock), and irritability, combined with a **46,XX karyotype** and normal ovaries, is classic for **Congenital Adrenal Hyperplasia (CAH)**, most commonly due to **21-hydroxylase deficiency**. **1. Why Hyperglycemia is the Correct Answer:** In 21-hydroxylase deficiency, there is a block in the conversion of progesterone to deoxycorticosterone and 17-hydroxyprogesterone to 11-deoxycortisol. This leads to a **deficiency in Cortisol**. Since cortisol is a counter-regulatory hormone that promotes gluconeogenesis and glycogenolysis, its absence leads to **Hypoglycemia**, not hyperglycemia. Therefore, hyperglycemia is not typically seen in this scenario. **2. Analysis of Incorrect Options:** * **Hyponatremia & Hyperkalemia:** These occur due to **Aldosterone deficiency**. Aldosterone normally reabsorbs sodium and excretes potassium/hydrogen ions in the distal tubule. Its absence leads to "salt-wasting," resulting in low sodium and high potassium. * **Hypoglycemia:** As explained above, this is a direct result of glucocorticoid (cortisol) deficiency. **Clinical Pearls for NEET-PG:** * **Most Common Cause:** 21-hydroxylase deficiency (90-95% of CAH cases). * **Diagnostic Marker:** Elevated levels of **17-hydroxyprogesterone (17-OHP)**. * **Genitalia:** In 46,XX females, excess androgens cause **ambiguous genitalia** (virilization), though internal organs (ovaries/uterus) remain normal. * **Management:** Acute adrenal crisis requires aggressive fluid resuscitation (Normal Saline) and IV Hydrocortisone. * **Karyotype Tip:** Always look for the mismatch between karyotype (46,XX) and physical signs of virilization to spot CAH questions.

Question 52: Inheritance pattern of Familial hypophosphatemic Rickets is:

A. Autosomal recessive
B. X-linked dominant (Correct Answer)
C. X-linked recessive
D. Autosomal dominant

Explanation: **Explanation:** **Familial Hypophosphatemic Rickets (FHR)**, also known as Vitamin D-resistant rickets, is most commonly caused by a mutation in the **PHEX gene** (Phosphate regulating gene with Homologies to endopeptidases on the X chromosome). 1. **Why X-linked Dominant is Correct:** The PHEX mutation leads to increased levels of **FGF-23** (Fibroblast Growth Factor-23), a phosphaturic hormone. Excess FGF-23 inhibits renal phosphate reabsorption and suppresses the activation of Vitamin D (1-alpha-hydroxylase activity). Because it is **X-linked dominant**, the condition is expressed in both hemizygous males and heterozygous females. It is one of the classic examples of X-linked dominant inheritance frequently tested in NEET-PG. 2. **Why Other Options are Incorrect:** * **Autosomal Recessive/Dominant:** While rare forms of hypophosphatemic rickets exist (e.g., ADHR or ARHR), the "Familial" or "Classic" form specifically refers to the X-linked variety. * **X-linked Recessive:** In FHR, a single mutant allele on the X chromosome is sufficient to cause the clinical phenotype in females; therefore, it is not recessive. **High-Yield Clinical Pearls for NEET-PG:** * **Biochemical Profile:** Low serum phosphate, **Normal** serum calcium, **Normal** 25(OH)D, but inappropriately low/normal 1,25(OH)₂D, and **Elevated Alkaline Phosphatase**. * **Clinical Feature:** Unlike nutritional rickets, **rachitic rosary and tetany are rare**; the primary manifestation is lower limb bowing and short stature. * **Treatment:** Oral phosphate supplementation and **Calcitriol** (active Vitamin D). * **Rule of Thumb:** If a question mentions "Rickets non-responsive to Vitamin D," think of FHR or Vitamin D Dependent Rickets (VDDR).

Question 53: Ambiguous genitalia in males is due to which of the following conditions?

A. Congenital adrenal hyperplasia
B. Cushing's disease
C. 5-alpha reductase deficiency (Correct Answer)
D. Aromatase deficiency

Explanation: **Explanation:** Ambiguous genitalia in a genotypic male (46,XY) occurs when there is a failure in the synthesis or action of androgens during fetal development. **Correct Option: C. 5-alpha reductase deficiency** The enzyme 5-alpha reductase is responsible for converting Testosterone into the more potent **Dihydrotestosterone (DHT)**. While testosterone mediates the development of internal male structures (Wolffian ducts), DHT is essential for the virilization of external genitalia (penis, scrotum, and prostate). In this deficiency, 46,XY individuals have internal male structures (testes, vas deferens) but present with ambiguous or female-appearing external genitalia at birth. A classic clinical feature is "virilization at puberty" due to the surge in testosterone. **Incorrect Options:** * **A. Congenital Adrenal Hyperplasia (CAH):** This is the most common cause of ambiguous genitalia in **females (46,XX)** due to excess androgens (e.g., 21-hydroxylase deficiency). In males, it typically causes precocious puberty or salt-wasting, not ambiguous genitalia. * **B. Cushing’s Disease:** This involves excess cortisol production. It does not interfere with primary sexual differentiation in the fetus. * **D. Aromatase Deficiency:** Aromatase converts androgens to estrogens. Deficiency in a female fetus leads to virilization (ambiguous genitalia) because excess fetal androgens cannot be converted to estrogen. In males, it leads to tall stature and osteoporosis, but not ambiguous genitalia. **High-Yield Clinical Pearls for NEET-PG:** * **Mullerian Inhibiting Substance (MIS):** In 5-alpha reductase deficiency, MIS is present; therefore, there is **no uterus or fallopian tubes**. * **Testosterone/DHT Ratio:** An increased ratio after HCG stimulation is diagnostic for 5-alpha reductase deficiency. * **Androgen Insensitivity Syndrome (AIS):** Another cause of ambiguous genitalia/female phenotype in males, but unlike 5-alpha reductase deficiency, there is a defect in the androgen receptor itself.

Question 54: The parents of a 4-week-old girl complain that their baby is apathetic and sluggish. On physical examination, the child's abdomen is large and exhibits an umbilical hernia. The skin is pale and cold, and the temperature is 35°C (95°F). Which of the following provides a plausible explanation for the signs and symptoms of this child?

A. Cystic fibrosis
B. Muscular dystrophy
C. Parathyroid hyperplasia
D. Thyroid agenesis (Correct Answer)

Explanation: **Explanation:** The clinical presentation of apathy, sluggishness, an umbilical hernia, a protuberant abdomen, and hypothermia (35°C) in a 4-week-old infant is a classic description of **Congenital Hypothyroidism**. **1. Why Thyroid Agenesis is Correct:** Thyroid dysgenesis (which includes **agenesis**, hypoplasia, or ectopy) is the most common cause of permanent congenital hypothyroidism (85%). Thyroid hormones are essential for metabolic rate and thermogenesis; hence, deficiency leads to hypothermia and cold, pale skin. The "sluggishness" reflects CNS depression and decreased metabolic activity. Other classic signs include a large fontanelle, macroglossia, and a characteristic umbilical hernia due to hypotonia of the abdominal muscles. **2. Why Incorrect Options are Wrong:** * **Cystic Fibrosis:** Typically presents with meconium ileus in neonates or failure to thrive and recurrent pneumonia later. It does not cause umbilical hernia or significant hypothermia. * **Muscular Dystrophy:** Duchenne or Becker muscular dystrophy usually manifests in early childhood (3–5 years) with motor delays, not as a multisystem metabolic collapse in a 4-week-old. * **Parathyroid Hyperplasia:** This would lead to hypercalcemia. While it can cause lethargy, it does not explain the umbilical hernia or the specific cutaneous and thermoregulatory findings seen here. **Clinical Pearls for NEET-PG:** * **Most common cause worldwide:** Iodine deficiency. * **Most common cause in non-endemic areas:** Thyroid dysgenesis (Agenesis is the most severe form). * **Screening:** Done via heel-prick test (TSH levels) at 48–72 hours of life. * **Treatment:** Levothyroxine must be started immediately to prevent permanent **neurocognitive impairment (Cretinism)**. * **Early Sign:** Prolonged physiological jaundice is often the earliest clinical clue.

Question 55: Which statin is indicated for an 8-year-old child diagnosed with heterozygous familial hypercholesterolemia?

A. Simvastatin
B. Pravastatin (Correct Answer)
C. Atorvastatin
D. Lovastatin

Explanation: **Explanation:** The management of **Heterozygous Familial Hypercholesterolemia (HeFH)** in children focuses on lifestyle modifications followed by pharmacotherapy if LDL-C levels remain significantly elevated (typically >190 mg/dL or >160 mg/dL with a family history of early CVD). **Why Pravastatin is correct:** Pravastatin is unique because it is the only statin FDA-approved for use in children as young as **8 years old**. Most other statins are approved for children aged **10 years and older**. This makes Pravastatin the drug of choice when pharmacological intervention is required in the 8–10 year age bracket. **Analysis of Incorrect Options:** * **Simvastatin (A), Atorvastatin (C), and Lovastatin (D):** While these are commonly used to treat pediatric dyslipidemia, they are generally indicated for children **≥10 years of age**. Starting these medications in an 8-year-old would be considered "off-label" compared to the specific approval profile of Pravastatin. **High-Yield Clinical Pearls for NEET-PG:** * **Age of Initiation:** Statin therapy is generally not started before the age of 8 unless the child has **Homozygous** Familial Hypercholesterolemia (which requires much earlier, aggressive intervention). * **Monitoring:** Before starting statins, baseline Liver Function Tests (ALT/AST) and Creatine Kinase (CK) levels should be obtained. * **Teratogenicity:** Statins are **Category X**; adolescent females must be counseled on contraception. * **First-line:** Lifestyle and dietary changes (Step II AHA diet) should be trialed for 6–12 months before initiating drugs.

Question 56: A child underwent bilateral adrenalectomy. Later, the child developed headache, visual field defect, and hyperpigmentation of the skin. What is the most probable diagnosis?

A. Pituitary adenoma
B. Allgrove syndrome
C. Wolman syndrome
D. Nelson syndrome (Correct Answer)

Explanation: ### Explanation **Nelson Syndrome** is the correct diagnosis. It is a rare complication that occurs following **bilateral adrenalectomy**, typically performed as a treatment for refractory Cushing’s disease. **Pathophysiology:** When both adrenal glands are removed, the negative feedback loop provided by cortisol is eliminated. In response, the pre-existing pituitary microadenoma (which originally caused the Cushing’s disease) undergoes rapid, aggressive growth. This leads to: 1. **Hyperpigmentation:** Massive secretion of Adrenocorticotropic Hormone (ACTH) and its precursor, Pro-opiomelanocortin (POMC), which contains Melanocyte-Stimulating Hormone (MSH) sequences. 2. **Mass Effect:** The enlarging pituitary tumor compresses surrounding structures, leading to **headaches** and **visual field defects** (typically bitemporal hemianopia due to optic chiasm compression). --- ### Why the other options are incorrect: * **A. Pituitary Adenoma:** While Nelson syndrome involves a pituitary adenoma, "Pituitary Adenoma" is too broad. Nelson syndrome specifically refers to the aggressive growth of an ACTH-secreting tumor *post-adrenalectomy*. * **B. Allgrove Syndrome (Triple A Syndrome):** Characterized by **A**chalasia cardia, **A**lacrimia, and **A**drenal insufficiency (ACTH resistance). It does not involve pituitary enlargement or post-surgical hyperpigmentation. * **C. Wolman Syndrome:** A lysosomal storage disorder (acid lipase deficiency) presenting with hepatosplenomegaly and **bilateral adrenal calcification**, not post-surgical pituitary growth. --- ### High-Yield Clinical Pearls for NEET-PG: * **Classic Triad of Nelson Syndrome:** History of bilateral adrenalectomy + Hyperpigmentation + Signs of expanding pituitary mass. * **Investigation of Choice:** MRI of the brain (pituitary) and plasma ACTH levels (markedly elevated). * **Prevention:** Modern management of Cushing’s disease focuses on transsphenoidal pituitary surgery or radiotherapy to avoid the need for bilateral adrenalectomy, thereby reducing the incidence of Nelson syndrome.

Question 57: What is the most common presentation of hypoparathyroidism beyond the neonatal period?

A. Syncope secondary to prolonged QT intervals
B. Tingling of extremities (Correct Answer)
C. Seizure
D. Bronchospasm

Explanation: **Explanation:** Hypoparathyroidism, characterized by deficient Parathyroid Hormone (PTH), leads to **hypocalcemia** and hyperphosphatemia. Beyond the neonatal period, the most common clinical presentation is related to increased neuromuscular irritability. **1. Why "Tingling of extremities" is correct:** Hypocalcemia lowers the threshold for axonal depolarization. The earliest and most frequent symptoms are sensory disturbances, specifically **paresthesias** (tingling and numbness) of the fingertips, toes, and perioral region. This reflects mild to moderate neuromuscular irritability before progressing to motor symptoms like tetany. **2. Analysis of Incorrect Options:** * **Seizure (Option C):** While seizures are a common presentation in the *neonatal* period or in cases of severe, acute hypocalcemia, they are less frequent than sensory symptoms in older children and adults. * **Syncope (Option A):** Hypocalcemia causes **prolonged QT intervals** on ECG, which can predispose to Torsades de Pointes and syncope. However, this is a serious complication rather than the most common presenting symptom. * **Bronchospasm (Option D):** Hypocalcemic tetany can involve smooth muscles, leading to laryngospasm or bronchospasm. These are life-threatening but rare manifestations compared to peripheral paresthesias. **NEET-PG High-Yield Pearls:** * **Physical Signs:** Look for **Chvostek sign** (facial twitching on tapping the facial nerve) and **Trousseau sign** (carpal spasm after inflating a BP cuff above systolic pressure). Trousseau sign is more sensitive and specific. * **ECG Finding:** The classic finding is **prolonged QT interval** due to lengthening of the ST segment. * **DiGeorge Syndrome:** A key cause of congenital hypoparathyroidism (CATCH-22: Cardiac defects, Abnormal facies, Thymic hypoplasia, Cleft palate, Hypocalcemia). * **Lab Profile:** Low Calcium, High Phosphorus, Low PTH (except in Pseudohypoparathyroidism where PTH is high).

Question 58: Which of the following is NOT a known cause of precocious puberty?

A. Primary hypothyroidism
B. Congenital adrenal hyperplasia
C. Theca cell tumor of the ovary
D. Secondary hypothyroidism (Correct Answer)

Explanation: **Explanation:** Precocious puberty is defined as the onset of secondary sexual characteristics before age 8 in girls and age 9 in boys. Understanding the hormonal axis is key to identifying its causes. **Why Secondary Hypothyroidism is the correct answer:** Secondary (central) hypothyroidism is characterized by a deficiency in TSH or TRH. This leads to low thyroid hormone levels without an increase in pituitary activity that could cross-react with gonadotropin receptors. It is associated with **delayed puberty**, not precocious puberty. **Analysis of Incorrect Options:** * **Primary Hypothyroidism:** This is a classic cause of "Van Wyk-Grumbach Syndrome." In severe primary hypothyroidism, extremely high levels of TSH (due to lack of feedback) can cross-react with FSH receptors because they share a common alpha-subunit. This leads to precocious puberty, often characterized by multicystic ovaries and vaginal bleeding in girls, or testicular enlargement in boys, without a bone age advancement. * **Congenital Adrenal Hyperplasia (CAH):** This causes **peripheral precocious puberty** (isosexual in boys, contrasexual in girls). Excess adrenal androgens lead to early development of pubic hair and phallic enlargement. * **Theca Cell Tumor:** These are ovarian tumors that secrete estrogen directly, leading to peripheral precocious puberty (isosexual) in girls, characterized by breast development and vaginal bleeding. **NEET-PG High-Yield Pearls:** * **Van Wyk-Grumbach Syndrome:** The triad of primary hypothyroidism, precocious puberty, and delayed bone age (unique, as most precocity advances bone age). * **True vs. Pseudo:** Central precocity (GnRH dependent) always involves early activation of the HPO axis; Peripheral precocity (GnRH independent) involves exogenous or ectopic sex steroids. * **McCune-Albright Syndrome:** Triad of polyostotic fibrous dysplasia, café-au-lait spots (Coast of Maine), and peripheral precocious puberty.

Question 59: Precocious puberty is seen in which of the following conditions?

A. Hypothyroidism
B. CNS irradiation
C. McCune-Albright syndrome
D. All of the above (Correct Answer)

Explanation: **Explanation:** Precocious puberty is defined as the onset of secondary sexual characteristics before age 8 in girls and age 9 in boys. It is broadly classified into **Central (GnRH-dependent)** and **Peripheral (GnRH-independent)** types. * **McCune-Albright Syndrome (MAS):** This is a classic cause of **Peripheral Precocious Puberty**. It is characterized by the triad of polyostotic fibrous dysplasia, café-au-lait spots (Coast of Maine borders), and autonomous endocrine overactivity (most commonly precocious puberty due to ovarian cysts in girls). It results from a somatic mutation in the *GNAS* gene. * **CNS Irradiation:** Low-dose cranial irradiation (often for leukemia or brain tumors) can trigger **Central Precocious Puberty**. It is thought to disrupt the inhibitory pathways that normally keep the GnRH pulse generator dormant during childhood, leading to premature activation of the Hypothalamic-Pituitary-Gonadal (HPG) axis. * **Hypothyroidism:** Severe, untreated primary hypothyroidism can cause **Van Wyk-Grumbach Syndrome**. High levels of TSH cross-react with FSH receptors (due to molecular mimicry), leading to precocious puberty, multicystic ovaries, and delayed bone age (unlike other forms of precocity where bone age is advanced). **Clinical Pearls for NEET-PG:** 1. **Bone Age:** In most precocious puberty, bone age is **advanced**. In Hypothyroidism-induced precocity, bone age is **delayed**. 2. **Treatment:** GnRH agonists (e.g., Leuprolide) are the treatment of choice for Central Precocious Puberty. 3. **Hamartoma:** Hypothalamic hamartoma is the most common organic cause of Central Precocious Puberty.

Question 60: Male pseudohermaphroditism is seen in which of the following conditions?

A. 5-alpha-reductase deficiency (Correct Answer)
B. 21-hydroxylase deficiency
C. 17-hydroxylase deficiency
D. Gonadal dysgenesis

Explanation: **Explanation:** **1. Why 5-alpha-reductase deficiency is correct:** Male pseudohermaphroditism (now termed **46,XY Disorder of Sex Development**) occurs when an individual has a 46,XY genotype and testes, but the external genitalia are undervirilized or female. In **5-alpha-reductase deficiency**, the body cannot convert Testosterone into the more potent **Dihydrotestosterone (DHT)**. Since DHT is essential for the development of male external genitalia (penis, scrotum, prostate), these patients are born with ambiguous genitalia or a female appearance. However, internal male structures (epididymis, vas deferens) are present because they depend on Testosterone, not DHT. **2. Why the other options are incorrect:** * **21-hydroxylase deficiency:** This is the most common cause of Congenital Adrenal Hyperplasia (CAH). It leads to **Female pseudohermaphroditism** (46,XX with virilized genitalia) due to excess androgen production. * **17-hydroxylase deficiency:** In 46,XY individuals, this causes a lack of both cortisol and sex hormones, leading to female external genitalia. However, it is classically associated with **hypertension and hypokalemia** due to mineralocorticoid excess, distinguishing it from isolated 5-alpha-reductase deficiency. * **Gonadal dysgenesis:** This refers to the incomplete development of gonads (e.g., Turner Syndrome 45,X). It typically results in "streak gonads" rather than functioning testes. **Clinical Pearls for NEET-PG:** * **"Penis-at-12" syndrome:** In 5-alpha-reductase deficiency, a surge of testosterone at puberty causes virilization (clitoral enlargement, muscle mass increase), often leading to a change in gender identity from female to male. * **Müllerian Inhibiting Substance (MIS):** In 5-alpha-reductase deficiency, MIS is normal; therefore, the uterus and fallopian tubes are **absent**. * **Key Distinction:** 5-alpha-reductase deficiency (Normal Testosterone/Low DHT) vs. Androgen Insensitivity Syndrome (High Testosterone/High LH).

Practice by Chapter

Disorders of Growth

Practice Questions

Thyroid Disorders

Practice Questions

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

Practice Questions

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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