Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 221: What is the drug of choice for a pregnant female suspected of having a baby with congenital adrenal hyperplasia?

A. Dexamethasone (Correct Answer)
B. Aldosterone
C. Hydrocortisone
D. Prednisolone

Explanation: **Explanation:** The primary goal of prenatal treatment in **Congenital Adrenal Hyperplasia (CAH)**, specifically 21-hydroxylase deficiency, is to prevent the **virilization (ambiguous genitalia)** of a female fetus. **Why Dexamethasone is the Correct Answer:** Dexamethasone is the drug of choice because it is **not inactivated by the placental enzyme 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2)**. Unlike other steroids, it crosses the placenta in its active form, reaches the fetal circulation, and suppresses the fetal pituitary ACTH secretion. This reduces the production of adrenal androgens, thereby preventing masculinization of the female external genitalia. Treatment must be started early (before the 9th week of gestation) to be effective. **Why Other Options are Incorrect:** * **Hydrocortisone and Prednisolone:** These are inactivated by the placental enzyme 11β-HSD2. They are used to treat the mother’s own symptoms but do not reach the fetus in sufficient concentrations to suppress the fetal adrenal gland. * **Aldosterone:** This is a mineralocorticoid. While CAH often involves salt-wasting, prenatal treatment focuses on androgen suppression via the glucocorticoid pathway, not mineralocorticoid replacement. **NEET-PG High-Yield Pearls:** * **Timing:** Treatment must begin as soon as pregnancy is confirmed (ideally by **6–7 weeks**) and before the **9th week**, as genital differentiation begins then. * **Diagnosis:** If the fetus is later determined to be male or an unaffected female (via CVS or amniocentesis), dexamethasone is discontinued. * **Dose:** Standard dose is 20 μg/kg/day in three divided doses. * **Gold Standard for Postnatal Diagnosis:** 17-hydroxyprogesterone (17-OHP) levels.

Question 222: A 4-year-old child presents with lethargy, delayed development of epiphysis, retarded dental eruption, growth retardation, mental retardation, and a slow relaxation component of deep tendon reflexes. What is the most likely diagnosis?

A. Rickets
B. Hypothyroidism (Correct Answer)
C. Scurvy
D. Hypoparathyroidism

Explanation: **Explanation:** The clinical presentation described is a classic manifestation of **Juvenile Hypothyroidism**. Thyroid hormones are essential for the normal maturation of the skeletal, dental, and central nervous systems. * **Why Hypothyroidism is correct:** 1. **Skeletal & Dental:** Thyroid hormone is crucial for linear growth and bone maturation. Deficiency leads to growth retardation, **delayed epiphyseal appearance/dysgenesis**, and delayed dental eruption. 2. **Neurological:** It is vital for brain development; deficiency causes lethargy and **mental retardation** (permanent if not treated early). 3. **Reflexes:** A hallmark sign of hypothyroidism is the **"hung-up" reflex**, characterized by a slow relaxation phase of deep tendon reflexes (Woltman sign) due to delayed calcium reuptake by the sarcoplasmic reticulum. * **Why other options are incorrect:** * **Rickets:** Presents with bony deformities (bow legs, rachitic rosary) and delayed walking, but it does not typically cause mental retardation or slow reflex relaxation. * **Scurvy:** Caused by Vitamin C deficiency; presents with irritability, subperiosteal hemorrhages (pseudoparalysis), and "frog-leg" position, but not delayed epiphysis or mental retardation. * **Hypoparathyroidism:** Characterized by neuromuscular irritability (tetany, Chvostek/Trousseau signs) due to hypocalcemia, rather than slow reflexes. **NEET-PG High-Yield Pearls:** * **Most common cause of preventable mental retardation:** Congenital Hypothyroidism. * **Most common cause of Hypothyroidism (Worldwide):** Iodine deficiency. * **Most common cause (Developed countries/Sporadic):** Thyroid dysgenesis (Ectopic gland is the most common type). * **Radiological sign:** "Fragmentation" or "Stippled" epiphysis (Epiphyseal dysgenesis).

Question 223: What is the most common cause of congenital hypothyroidism?

A. Thyroid dysgenesis (Correct Answer)
B. Dyshormonogenesis
C. Antithyroid antibodies
D. Maternal hypothyroidism

Explanation: **Explanation:** Congenital Hypothyroidism (CH) is the most common preventable cause of intellectual disability worldwide. **1. Why Thyroid Dysgenesis is Correct:** Thyroid dysgenesis refers to an embryological defect in the development of the thyroid gland. It accounts for approximately **80–85% of cases** of permanent congenital hypothyroidism. It includes: * **Ectopy:** The most common specific type (the gland is usually located at the base of the tongue). * **Aplasia/Agenesis:** Complete absence of the gland. * **Hypoplasia:** An underdeveloped gland in the normal location. Most cases are sporadic and not inherited. **2. Why the Other Options are Incorrect:** * **B. Dyshormonogenesis (10–15%):** This refers to genetic defects in the thyroid hormone synthesis pathway (e.g., TPO deficiency). Unlike dysgenesis, this usually presents with a **goiter** and follows an autosomal recessive inheritance pattern. * **C. Antithyroid antibodies:** Transplacental passage of maternal TSH-receptor blocking antibodies (TRBAb) causes **transient** neonatal hypothyroidism, not the most common permanent form. * **D. Maternal hypothyroidism:** While maternal iodine deficiency is a leading cause of hypothyroidism globally (Endemic Cretinism), maternal hypothyroidism itself does not typically cause permanent congenital hypothyroidism in the newborn if the infant's thyroid gland is intact. **High-Yield Clinical Pearls for NEET-PG:** * **Screening:** Best done at **48–72 hours** of life to avoid the physiological TSH surge. * **Clinical Features:** Most infants are asymptomatic at birth. Early signs include a large posterior fontanelle (>0.5 cm), prolonged physiological jaundice, umbilical hernia, and hoarse cry. * **Radiology:** Absence of the **distal femoral epiphysis** on X-ray at birth indicates significant in-utero hypothyroidism. * **Treatment:** Levothyroxine (10–15 μg/kg/day) should be started immediately to prevent neurodevelopmental delay.

Question 224: Hypoglycemia, jaundice, and microphallus with an absent septum pellucidum are characteristic features of which syndrome?

A. De Morsier syndrome (Correct Answer)
B. Silver-Russell syndrome
C. Kallmann syndrome
D. Kearns-Sayre syndrome

Explanation: **Explanation:** The correct answer is **De Morsier syndrome**, also known as **Septo-optic Dysplasia (SOD)**. This is a rare congenital disorder characterized by a classic triad: 1. **Optic nerve hypoplasia:** Leading to visual impairment. 2. **Midline brain defects:** Specifically an **absent septum pellucidum** or corpus callosum agenesis. 3. **Pituitary hypoplasia:** Resulting in combined pituitary hormone deficiencies. The clinical features mentioned—**hypoglycemia** (due to GH and ACTH deficiency), **jaundice** (cholestasis from GH/TSH deficiency), and **microphallus** (due to gonadotropin deficiency)—are all manifestations of congenital hypopituitarism associated with this syndrome. **Analysis of Incorrect Options:** * **Silver-Russell Syndrome:** Characterized by intrauterine growth restriction (IUGR), triangular facies, limb asymmetry, and clinodactyly. It does not involve midline brain defects. * **Kallmann Syndrome:** Defined by hypogonadotropic hypogonadism and **anosmia** (loss of smell) due to failure of GnRH neuron migration. It does not typically present with neonatal hypoglycemia or absent septum pellucidum. * **Kearns-Sayre Syndrome:** A mitochondrial DNA deletion syndrome characterized by the triad of progressive external ophthalmoplegia, pigmentary retinopathy, and heart block. **High-Yield Pearls for NEET-PG:** * **Imaging Gold Standard:** MRI is the investigation of choice to visualize the absent septum pellucidum and pituitary stalk abnormalities. * **Neonatal Emergency:** Any male neonate presenting with **microphallus and hypoglycemia** should be urgently evaluated for congenital hypopituitarism to prevent adrenal crisis. * **Association:** SOD is sometimes associated with mutations in the *HESX1* gene.

Question 225: Precocious puberty may be seen in all of the following conditions except?

A. Granulosa cell tumor
B. Head injury
C. Corticosteroid intake
D. Hyperthyroidism (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 categorized into **GnRH-dependent** (Central) and **GnRH-independent** (Peripheral) types. **Why Hyperthyroidism is the correct answer:** Hyperthyroidism is **not** associated with precocious puberty. In fact, it is **Hypothyroidism** (specifically severe, untreated primary hypothyroidism) that causes precocious puberty (Van Wyk-Grumbach Syndrome). In this syndrome, high levels of TSH cross-react with FSH receptors due to molecular mimicry, leading to gonadal stimulation. Hyperthyroidism, conversely, does not trigger the hypothalamic-pituitary-gonadal axis in this manner. **Analysis of other options:** * **Granulosa cell tumor:** This is a common cause of **Peripheral Precocious Puberty** in girls. These ovarian tumors secrete estrogen directly, leading to breast development and vaginal bleeding regardless of GnRH levels. * **Head injury:** Any CNS insult (trauma, tumors like hamartomas, or infections) can trigger the premature activation of the pulse generator in the hypothalamus, leading to **Central Precocious Puberty**. * **Corticosteroid intake:** Exogenous administration of anabolic steroids or exposure to estrogenic/androgenic creams can cause **Peripheral Precocious Puberty** by directly introducing sex hormones into the systemic circulation. **High-Yield Clinical Pearls for NEET-PG:** * **McCune-Albright Syndrome:** Triad of peripheral precocious puberty, café-au-lait spots (Coast of Maine), and polyostotic fibrous dysplasia. * **Most common cause of Central Precocious Puberty:** Idiopathic (Girls) > CNS lesions (Boys). * **Bone Age:** Always advanced in true precocious puberty. * **Treatment of choice for Central Precocious Puberty:** Long-acting GnRH agonists (e.g., Leuprolide).

Question 226: Adrenogenital syndrome is most commonly caused by which of the following deficiencies?

A. 21-alpha hydroxylase deficiency (Correct Answer)
B. 17-alpha hydroxylase deficiency
C. 3-beta hydroxylase deficiency
D. Steroid sulfatase deficiency

Explanation: **Explanation:** **Adrenogenital Syndrome**, more commonly known as **Congenital Adrenal Hyperplasia (CAH)**, results from an enzymatic defect in the steroidogenesis pathway of the adrenal cortex. **Why 21-alpha hydroxylase deficiency is correct:** Approximately **90-95% of all CAH cases** are caused by a deficiency of the **21-hydroxylase enzyme** (encoded by the *CYP21A2* gene). This enzyme is essential for converting progesterone to 11-deoxycorticosterone (mineralocorticoid pathway) and 17-OH progesterone to 11-deoxycortisol (glucocorticoid pathway). Its deficiency leads to: 1. **Decreased Cortisol:** Triggers increased ACTH secretion via negative feedback. 2. **Adrenal Hyperplasia:** ACTH overstimulates the adrenal cortex. 3. **Androgen Excess:** Precursors are shunted toward the androgen pathway, causing virilization (ambiguous genitalia in females) and precocious puberty in males. **Why the other options are incorrect:** * **17-alpha hydroxylase deficiency:** Rare; it leads to decreased sex hormones and cortisol but **increased mineralocorticoids**, resulting in hypertension and hypokalemia. * **3-beta hydroxylase deficiency:** Rare; it blocks the synthesis of all three classes of adrenal steroids (mineralocorticoids, glucocorticoids, and sex steroids), leading to salt-wasting and incomplete virilization. * **Steroid sulfatase deficiency:** This is associated with **X-linked Ichthyosis**, not CAH or virilizing adrenal syndromes. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnostic Marker:** Elevated levels of **17-Hydroxyprogesterone (17-OHP)** is the gold standard for screening/diagnosis. * **Classic Presentation:** Salt-wasting (hypotension, hyponatremia, hyperkalemia) and ambiguous genitalia in newborn females. * **Management:** Glucocorticoid (Hydrocortisone) to suppress ACTH and Fludrocortisone for salt-wasting. * **Most common cause of ambiguous genitalia** in a genetically female (46, XX) newborn is 21-hydroxylase deficiency.

Question 227: A 9-year-old girl presents with menarche. Her history reveals thelarche at 7 years and adrenarche at 8 years. What is the most common cause of this condition in girls?

A. Idiopathic (Correct Answer)
B. Gonadal tumor
C. McCune-Albright syndrome
D. Hypothyroidism

Explanation: ### Explanation The clinical presentation describes **Central Precocious Puberty (CPP)**, defined as the onset of secondary sexual characteristics before age 8 in girls (or menarche before age 10). The sequence of development (thelarche → adrenarche → menarche) is normal, but the timing is accelerated due to the premature activation of the Hypothalamic-Pituitary-Gonadal (HPG) axis. **1. Why "Idiopathic" is correct:** In girls, approximately **80–90% of cases of Central Precocious Puberty are Idiopathic**. This means no underlying CNS pathology or systemic disease is identified. In contrast, CPP in boys is much more likely (up to 75%) to be associated with an identifiable organic lesion (e.g., hypothalamic hamartoma). **2. Why the other options are incorrect:** * **Gonadal Tumor:** These cause *Peripheral* Precocious Puberty (GnRH-independent). While they cause feminization, they do not activate the HPG axis and typically present with suppressed LH/FSH levels and an asynchronous sequence of puberty. * **McCune-Albright Syndrome:** This is a form of peripheral precocity characterized by the triad of polyostotic fibrous dysplasia, café-au-lait spots, and autonomous endocrine hyperfunction. It is a rare genetic cause, not the most common. * **Hypothyroidism:** Severe primary hypothyroidism can cause "Van Wyk-Grumbach Syndrome," leading to precocious puberty (usually with delayed bone age). However, this is a rare association and not the primary cause of CPP. **Clinical Pearls for NEET-PG:** * **Gold Standard Investigation:** GnRH stimulation test (a pubertal response shows a peak LH > 5–10 IU/L). * **Bone Age:** Typically advanced in CPP, leading to premature epiphyseal closure and short adult stature. * **Drug of Choice:** GnRH agonists (e.g., Leuprolide) are used to "suspend" puberty until an appropriate age. * **Neuroimaging:** An MRI of the brain is mandatory in all boys with CPP and girls presenting before age 6 to rule out CNS tumors (like Hamartomas).

Question 228: A child presents with features of hyperparathyroidism. All of the following are true regarding this condition except:

A. Raised serum calcium
B. Raised serum phosphorus (Correct Answer)
C. Raised alkaline phosphatase
D. Resorption of minerals from bones

Explanation: In **Primary Hyperparathyroidism**, the fundamental pathology is the overproduction of Parathyroid Hormone (PTH), usually due to a parathyroid adenoma. Understanding the physiological actions of PTH is key to solving this question. ### Why "Raised serum phosphorus" is the Correct Answer (The Exception) PTH acts directly on the proximal convoluted tubules of the kidney to **inhibit the reabsorption of phosphate**, leading to increased urinary excretion (phosphaturia). Consequently, the hallmark of hyperparathyroidism is **hypophosphatemia** (low serum phosphorus), not hyperphosphatemia. ### Explanation of Incorrect Options * **A. Raised serum calcium:** PTH increases serum calcium by stimulating osteoclastic bone resorption, increasing renal tubular reabsorption of calcium, and enhancing intestinal calcium absorption (via Vitamin D activation). Hypercalcemia is the most consistent finding. * **C. Raised alkaline phosphatase (ALP):** Increased PTH leads to high bone turnover. ALP is a marker of osteoblastic activity which occurs secondary to increased osteoclastic bone resorption. * **D. Resorption of minerals from bones:** PTH directly stimulates osteoclasts to break down the bone matrix, releasing calcium and phosphorus into the bloodstream. ### High-Yield NEET-PG Pearls * **Classic Triad:** Hypercalcemia, Hypophosphatemia, and Hypercalciuria (despite increased renal reabsorption, the filtered load of calcium exceeds the kidney's capacity). * **Radiological Sign:** Subperiosteal bone resorption, most classically seen on the radial aspect of the middle phalanges. * **Osteitis Fibrosa Cystica:** The end-stage bone manifestation characterized by "Brown tumors." * **Mnemonic for Symptoms:** "Stones (renal), bones (pain/fractures), groans (abdominal pain/constipation), and psychic overtones (depression/confusion)."

Question 229: An adolescent boy presents with endocrinopathy, fibrous dysplasia of bone, and hyperpigmentation. What is the probable diagnosis?

A. Alagille syndrome
B. McCune Albright syndrome (Correct Answer)
C. MEN Type 1
D. MEN Type 2

Explanation: ### Explanation The correct diagnosis is **McCune-Albright Syndrome (MAS)**. This condition is characterized by a classic triad resulting from a post-zygotic somatic mutation in the **GNAS1 gene**, which leads to constitutive activation of the Gs-alpha protein and overproduction of cAMP. **1. Why McCune-Albright Syndrome is Correct:** The clinical presentation in the question perfectly matches the MAS triad: * **Endocrinopathy:** Most commonly **precocious puberty** (gonadotropin-independent), but can also include hyperthyroidism, GH excess, or Cushing syndrome. * **Polyostotic Fibrous Dysplasia:** Bone is replaced by fibrous tissue, leading to fractures and a "ground-glass" appearance on X-ray. * **Hyperpigmentation:** Characterized by **Café-au-lait spots** with irregular borders, often described as the **"Coast of Maine"** appearance (unlike the smooth "Coast of California" spots seen in Neurofibromatosis Type 1). **2. Why the Other Options are Incorrect:** * **Alagille Syndrome:** An autosomal dominant disorder involving biliary hypoplasia (paucity of bile ducts), butterfly vertebrae, and peripheral pulmonary artery stenosis. It does not involve fibrous dysplasia. * **MEN Type 1 (Wermer Syndrome):** Characterized by the "3 Ps": **P**arathyroid hyperplasia, **P**ancreatic tumors, and **P**ituitary adenomas. * **MEN Type 2 (Sipple/Gorlin Syndrome):** Involves Medullary Thyroid Carcinoma, Pheochromocytoma, and either Parathyroid hyperplasia (2A) or Mucosal neuromas/Marfanoid habitus (2B). **High-Yield Clinical Pearls for NEET-PG:** * **Mutation:** Somatic mutation (not inherited); the severity depends on when the mutation occurs during embryogenesis (mosaicism). * **Radiology:** Fibrous dysplasia shows a characteristic **"Shepherd’s Crook" deformity** of the femur. * **Precocious Puberty:** In girls, it often presents with recurrent follicular cysts and vaginal bleeding.

Question 230: What is the recommended oral glucose dose for performing an oral glucose tolerance test in children?

A. 1.5 gm/kg
B. 1.75 gm/kg (Correct Answer)
C. 2 gm/kg
D. 2.5 gm/kg

Explanation: **Explanation:** The **Oral Glucose Tolerance Test (OGTT)** is a standardized diagnostic tool used to assess glucose metabolism and diagnose Diabetes Mellitus or Impaired Glucose Tolerance. In pediatric practice, the glucose load must be weight-adjusted to ensure accuracy and safety, unlike the fixed 75g dose used for adults. **Why 1.75 gm/kg is correct:** The standard recommendation by the **World Health Organization (WHO)** and the **American Diabetes Association (ADA)** for children is **1.75 gm/kg of anhydrous glucose**. This dose provides a sufficient metabolic challenge to the pediatric endocrine system without causing excessive osmotic side effects. However, a crucial caveat is that the total dose should **not exceed 75 grams**, regardless of the child's weight. **Analysis of Incorrect Options:** * **1.5 gm/kg:** This dose is insufficient to meet the standardized diagnostic criteria and may lead to false-negative results (under-diagnosis). * **2 gm/kg & 2.5 gm/kg:** These doses are excessively high for a standard OGTT. Higher glucose loads increase the risk of nausea, vomiting (which invalidates the test), and osmotic diarrhea in children. **High-Yield Clinical Pearls for NEET-PG:** * **Preparation:** The child should have an unrestricted carbohydrate diet for 3 days prior and must fast for 8–12 hours before the test. * **Diagnostic Cut-offs (2-hour plasma glucose):** * **Normal:** <140 mg/dL * **Impaired Glucose Tolerance (IGT):** 140–199 mg/dL * **Diabetes Mellitus:** ≥200 mg/dL * **Growth Hormone (GH) Suppression Test:** In children suspected of Gigantism/Acromegaly, the same OGTT dose (1.75 gm/kg) is used. Failure to suppress GH to <1 ng/mL is diagnostic.

Practice by Chapter

Disorders of Growth

Practice Questions

Thyroid Disorders

Practice Questions

Disorders of Puberty

Practice Questions

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

Practice Questions

Hypoglycemia

Practice Questions

Obesity and Metabolic Syndrome

Practice Questions

Pituitary Disorders

Practice Questions

Multiple Endocrine Neoplasia Syndromes

Practice Questions

Endocrine Emergencies

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