Endocrinology — MCQs

An 11-year-old patient with type 1 diabetes mellitus was on continuous subcutaneous insulin infusion (CSII). During a holiday, she became disoriented. On admission, her laboratory values were: Sodium = 126 mEq/dL, Potassium = 4.3 mEq/dL, BUN = 100 mg/dL, Bicarbonate = 10 mEq/dL, and Blood Sugar = 600 mg%. Which of the following is NOT required for management?

Q96Easy

True precocious puberty can occur in all of the following conditions, except?

Q97Medium

A 2-month-old infant presents with failure to thrive, recurrent emesis, hepatosplenomegaly, and adrenal insufficiency. Adrenal calcification is noted radiologically. What is the most likely diagnosis?

Q98Medium

A child presents with decreased serum calcium, increased serum phosphorus, and decreased urinary calcium and phosphorus. Which condition is most likely?

Q99Medium

A 2-week-old baby presents with scrotal pigmentation, hyponatremia, hypoglycemia, and hyperkalemia. Which enzyme deficiency is most likely responsible?

Q100Easy

Screening of neonatal thyroid disease is done by?

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 91: Type 1 diabetes in children is most commonly associated with which of the following conditions?

A. Obesity
B. Celiac disease (Correct Answer)
C. Down syndrome
D. Hypothyroidism

Explanation: **Explanation:** Type 1 Diabetes Mellitus (T1DM) is an autoimmune condition characterized by the destruction of pancreatic beta cells. It is frequently associated with other organ-specific autoimmune disorders due to a shared genetic predisposition, specifically linked to **HLA-DR3 and HLA-DR4** genotypes. **Why Celiac Disease is the correct answer:** Celiac disease is the most common autoimmune comorbidity associated with T1DM, affecting approximately **5–10%** of pediatric patients. Both conditions share common genetic loci (HLA-DQ2 and DQ8). Because many children with T1DM are asymptomatic for Celiac disease, clinical guidelines recommend routine screening using **Tissue Transglutaminase (tTG) IgA antibodies** at the time of T1DM diagnosis and periodically thereafter. **Analysis of Incorrect Options:** * **A. Obesity:** This is strongly associated with **Type 2 Diabetes**, not Type 1. T1DM typically presents with weight loss and a lean habitus. * **C. Down Syndrome:** While children with Down syndrome have an increased risk of autoimmune issues (including T1DM), the association is not as frequent or specific as the link between T1DM and Celiac disease. * **D. Hypothyroidism:** Autoimmune thyroiditis (Hashimoto’s) is the *second* most common autoimmune association in T1DM. While highly relevant, Celiac disease is often cited as the primary screening priority in pediatric T1DM protocols. **Clinical Pearls for NEET-PG:** * **Screening Rule:** Always screen T1DM patients for Celiac disease and Hypothyroidism (TSH/Anti-TPO). * **Genetic Markers:** HLA-DR3/DR4 (T1DM), HLA-DQ2/DQ8 (Celiac). * **Mauriac Syndrome:** A rare complication of poorly controlled T1DM characterized by growth failure, delayed puberty, and hepatomegaly. * **Diagnosis:** HbA1c ≥ 6.5% or Fasting Plasma Glucose ≥ 126 mg/dL.

Question 92: What is the eponymus Trisomy 18?

A. Cri du chat syndrome
B. Patau's syndrome
C. Down's syndrome
D. Edward's syndrome (Correct Answer)

Explanation: ### Explanation **Correct Option: D. Edward's syndrome** Edward’s syndrome is caused by **Trisomy 18** (47, XX/XY, +18). It is the second most common autosomal trisomy among live births after Down’s syndrome. The condition is characterized by severe intellectual disability and multi-system defects. The extra chromosome 18 usually results from a meiotic non-disjunction event, most commonly during maternal meiosis. **Analysis of Incorrect Options:** * **A. Cri du chat syndrome:** This is not a trisomy but a structural chromosomal abnormality involving a **partial deletion of the short arm of chromosome 5 (5p-)**. It is characterized by a high-pitched, cat-like cry. * **B. Patau's syndrome:** This refers to **Trisomy 13**. Clinical hallmarks include midline defects such as holoprosencephaly, cleft lip/palate, and polydactyly. * **C. Down's syndrome:** This refers to **Trisomy 21**, the most common viable autosomal trisomy. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Triad of Edward’s Syndrome:** Micrognathia (small jaw), Clenched fists with **overlapping fingers** (2nd and 5th fingers over 3rd and 4th), and **Rocker-bottom feet** (also seen in Trisomy 13). * **Cardiac Defects:** Ventricular Septal Defect (VSD) is the most common. * **Other Features:** Low-set "faun-like" ears, prominent occiput, and Horseshoe kidney. * **Screening:** On a Quadruple screen, Trisomy 18 typically shows **decreased levels of all markers** (AFP, hCG, uE3, and Inhibin A), unlike Down’s syndrome where hCG and Inhibin A are elevated.

Question 93: Common features of acquired hypothyroidism include all EXCEPT:

A. Growth retardation
B. Mental retardation (Correct Answer)
C. Delayed puberty
D. Pseudohypertrophy of muscles

Explanation: **Explanation:** The key to answering this question lies in understanding the **timing of brain development**. Thyroid hormones are critical for neurogenesis and myelination primarily during the first 2–3 years of life. * **Why B is correct:** In **acquired hypothyroidism** (onset after the age of 2–3 years), the brain is already structurally developed. Therefore, while these children may experience sluggishness, poor concentration, or declining school performance, they **do not develop permanent mental retardation**. Permanent intellectual disability is a hallmark of *congenital* hypothyroidism (Cretinism) if not treated early. * **Why A is incorrect:** Growth retardation is the most common clinical manifestation of acquired hypothyroidism. There is a marked decrease in growth velocity, often leading to short stature with delayed bone age. * **Why C is incorrect:** Hypothyroidism typically causes **delayed puberty**. However, in rare, severe cases, it can cause *Van Wyk-Grumbach syndrome*, characterized by precocious puberty due to high TSH levels cross-reacting with FSH receptors. * **Why D is incorrect:** This refers to **Kocher-Debre-Semelaigne syndrome**, where children with long-standing hypothyroidism develop generalized muscular "pseudohypertrophy" (especially in the calves), giving them a Herculean appearance. **NEET-PG High-Yield Pearls:** 1. **Most common cause** of acquired hypothyroidism worldwide: Hashimoto’s Thyroiditis. 2. **First clinical sign:** Deceleration of linear growth. 3. **Bone Age:** Characteristically delayed in hypothyroidism, unlike in genetic short stature. 4. **Dental Age:** Also delayed (delayed eruption of permanent teeth).

Question 94: Pheochromocytoma is a tumor of which gland or structure?

A. Pituitary gland
B. Adrenal medulla (Correct Answer)
C. Pancreas
D. Adrenal cortex

Explanation: **Explanation:** **Pheochromocytoma** is a catecholamine-secreting tumor derived from the **chromaffin cells** of the embryonic neural crest. The primary site for these cells is the **Adrenal Medulla** (Option B), which accounts for approximately 85–90% of cases. These tumors produce excess epinephrine, norepinephrine, and dopamine, leading to the classic clinical triad of episodic headache, sweating, and tachycardia. **Why other options are incorrect:** * **Pituitary Gland (A):** The pituitary consists of the adenohypophysis and neurohypophysis; tumors here (like prolactinomas) secrete hormones like GH, ACTH, or Prolactin, not catecholamines. * **Pancreas (C):** Pancreatic neuroendocrine tumors (e.g., Insulinoma, Gastrinoma) arise from islet cells. While they are part of the MEN 1 syndrome, they are unrelated to pheochromocytoma. * **Adrenal Cortex (D):** The cortex is of mesodermal origin and produces steroid hormones (cortisol, aldosterone, androgens). Tumors here lead to Cushing’s syndrome or Conn’s syndrome. **High-Yield Clinical Pearls for NEET-PG:** * **Rule of 10s:** 10% are bilateral, 10% are malignant, 10% are extra-adrenal (called **Paragangliomas**), and 10% occur in children. * **Associated Syndromes:** MEN 2A and 2B, von Hippel-Lindau (VHL) disease, and Neurofibromatosis type 1 (NF1). * **Diagnosis:** Best initial screening test is **urinary or plasma fractionated metanephrines**. * **Management:** Pre-operative stabilization requires **Alpha-blockade first** (e.g., Phenoxybenzamine) followed by Beta-blockade to prevent a hypertensive crisis.

Question 95: An 11-year-old patient with type 1 diabetes mellitus was on continuous subcutaneous insulin infusion (CSII). During a holiday, she became disoriented. On admission, her laboratory values were: Sodium = 126 mEq/dL, Potassium = 4.3 mEq/dL, BUN = 100 mg/dL, Bicarbonate = 10 mEq/dL, and Blood Sugar = 600 mg%. Which of the following is NOT required for management?

A. Arterial Blood Gas (ABG)
B. Potassium hydrogen phosphate
C. Intravenous potassium
D. 3% saline (Correct Answer)

Explanation: The patient presents with classic features of **Diabetic Ketoacidosis (DKA)**: hyperglycemia (600 mg%), metabolic acidosis (Bicarbonate 10 mEq/dL), and disorientation. The hyponatremia (126 mEq/dL) in this context is **"Dilutional Hyponatremia"** (Pseudohyponatremia) caused by the osmotic effect of high glucose pulling water into the extracellular space. ### Why 3% Saline is NOT required (Correct Option) In DKA, the sodium deficit is corrected by standard fluid resuscitation (usually 0.9% Normal Saline). **3% Saline (Hypertonic Saline)** is contraindicated because: 1. The hyponatremia is not absolute; for every 100 mg/dL rise in glucose above normal, the measured sodium drops by approximately 1.6 mEq/L. 2. Rapid correction of sodium in DKA increases the risk of **Cerebral Edema**, the leading cause of mortality in pediatric DKA. ### Explanation of Other Options * **A. Arterial Blood Gas (ABG):** Essential to assess the severity of acidosis (pH and Anion Gap) and monitor the response to treatment. * **B. Potassium hydrogen phosphate:** In DKA, phosphate is lost through osmotic diuresis. If levels drop significantly, replacement (often as potassium phosphate) is needed to prevent 2,3-DPG depletion and respiratory muscle weakness. * **C. Intravenous potassium:** Even if serum potassium appears normal (4.3 mEq/dL), there is a total body potassium deficit. Once insulin therapy starts, potassium shifts intracellularly, necessitating early replacement to prevent life-threatening hypokalemia. ### Clinical Pearls for NEET-PG * **Corrected Sodium Formula:** Measured Na + [1.6 × (Glucose - 100) / 100]. * **Insulin Dosing:** In pediatric DKA, start insulin infusion at **0.1 U/kg/hour** only *after* initial fluid bolus. * **Cerebral Edema Warning:** Sudden headache, bradycardia, or neurological deterioration during DKA treatment suggests cerebral edema; treat immediately with **Mannitol**, not fluid restriction.

Question 96: True precocious puberty can occur in all of the following conditions, except?

A. McCune Albright syndrome
B. Craniopharyngioma
C. Congenital adrenal hyperplasia (Correct Answer)
D. Hypothalamic hamartoma

Explanation: To understand this question, we must distinguish between **True (Central) Precocious Puberty (CPP)** and **Peripheral Precocious Puberty (PPP)**. ### 1. Why Congenital Adrenal Hyperplasia (CAH) is the Correct Answer CAH is a classic cause of **Peripheral Precocious Puberty**. In CAH (most commonly 21-hydroxylase deficiency), there is an enzymatic block leading to the overproduction of adrenal androgens. These androgens cause physical changes (pubic hair, phallic enlargement) independently of the Hypothalamic-Pituitary-Gonadal (HPG) axis. Because the HPG axis remains suppressed by the peripheral steroids, it is not "True" precocious puberty. *Note: Long-standing untreated CAH can eventually trigger the HPG axis (Secondary CPP), but primarily, CAH is a peripheral cause.* ### 2. Analysis of Incorrect Options * **Hypothalamic Hamartoma:** This is the most common organic cause of **True Precocious Puberty**. These tumors act as ectopic GnRH pulse generators, directly activating the HPG axis. * **Craniopharyngioma:** Any CNS lesion (tumors, trauma, or irradiation) that disrupts the inhibitory pathways to the hypothalamus can lead to the premature activation of GnRH secretion, causing **True Precocious Puberty**. * **McCune-Albright Syndrome:** While typically known for causing PPP (autonomous ovarian activation), it is a high-yield exception. In many cases, the early exposure to high bone age and sex steroids eventually triggers the HPG axis, leading to **combined/true precocious puberty**. ### 3. NEET-PG High-Yield Pearls * **Definition:** True Precocious Puberty is **GnRH-dependent** (elevated LH/FSH), whereas Peripheral is **GnRH-independent**. * **Gold Standard Test:** GnRH Stimulation Test. (In CPP, there is a pubertal LH response; in PPP, LH remains flat). * **Drug of Choice for CPP:** Long-acting GnRH agonists (e.g., Leuprolide) to desensitize the pituitary. * **Bone Age:** Advanced in both types, but height velocity is a crucial monitoring parameter.

Question 97: A 2-month-old infant presents with failure to thrive, recurrent emesis, hepatosplenomegaly, and adrenal insufficiency. Adrenal calcification is noted radiologically. What is the most likely diagnosis?

A. Adrenal hemorrhage
B. Wolman's disease (Correct Answer)
C. Pheochromocytoma
D. Addison's disease

Explanation: **Explanation:** **Wolman’s Disease** is the correct diagnosis. It is an autosomal recessive lysosomal storage disorder caused by a deficiency of the enzyme **Lysosomal Acid Lipase (LAL)**. This deficiency leads to the massive accumulation of cholesteryl esters and triglycerides in various organs. * **Clinical Presentation:** The classic triad includes failure to thrive (due to malabsorption), hepatosplenomegaly, and progressive adrenal insufficiency. * **Pathognomonic Sign:** Bilateral, enlarged, and **calcified adrenal glands** are the hallmark radiological finding in Wolman’s disease, occurring in approximately 90% of cases. **Analysis of Incorrect Options:** * **A. Adrenal Hemorrhage:** While it can cause adrenal calcification (usually as a late sequela) and insufficiency, it typically presents acutely in the neonatal period (e.g., birth trauma or sepsis) rather than as a progressive storage disorder with hepatosplenomegaly. * **C. Pheochromocytoma:** This is a catecholamine-secreting tumor. It is extremely rare in infants and presents with hypertension and tachycardia, not failure to thrive or adrenal insufficiency. * **D. Addison’s Disease:** This is a general term for primary adrenal insufficiency. While it explains the electrolyte imbalances, it does not account for the hepatosplenomegaly or the specific finding of adrenal calcification in an infant. **High-Yield Pearls for NEET-PG:** * **Enzyme Defect:** Lysosomal Acid Lipase (LAL). * **Cholesteryl Ester Storage Disease (CESD):** A milder, late-onset variant of LAL deficiency (Wolman is the severe, infantile form). * **Radiology:** "Snowstorm" appearance of the adrenals on X-ray/CT due to diffuse punctate calcifications. * **Prognosis:** Without enzyme replacement therapy (Sebelipase alfa), Wolman’s disease is usually fatal within the first year of life.

Question 98: A child presents with decreased serum calcium, increased serum phosphorus, and decreased urinary calcium and phosphorus. Which condition is most likely?

A. Renal tubular acidosis
B. Chronic renal failure (Correct Answer)
C. Nutritional rickets
D. Coeliac rickets

Explanation: **Explanation:** The biochemical profile of **decreased serum calcium**, **increased serum phosphorus**, and **decreased urinary excretion** of both is characteristic of **Chronic Renal Failure (CRF)**. In CRF, the kidneys cannot effectively excrete phosphorus, leading to **hyperphosphatemia**. High phosphorus levels directly complex with calcium and inhibit the enzyme 1-alpha-hydroxylase, leading to a deficiency of active Vitamin D (Calcitriol). This results in decreased intestinal calcium absorption (**hypocalcemia**). Because the Glomerular Filtration Rate (GFR) is severely reduced, the total filtered load of both calcium and phosphorus into the urine is significantly decreased, explaining the low urinary levels. **Analysis of Incorrect Options:** * **Renal Tubular Acidosis (RTA):** Typically presents with hypercalciuria (increased urinary calcium) due to the buffering of metabolic acidosis by bone, which releases calcium into the urine. * **Nutritional & Coeliac Rickets:** Both are forms of Vitamin D deficiency. While they present with low serum calcium, they characteristically show **low or normal serum phosphorus** (due to secondary hyperparathyroidism causing phosphaturia) and **increased** urinary phosphorus. **High-Yield Pearls for NEET-PG:** * **Secondary Hyperparathyroidism:** In CRF, hypocalcemia and hyperphosphatemia trigger a massive rise in PTH to normalize calcium at the expense of bone (Renal Osteodystrophy). * **FGF-23:** This hormone rises early in CRF to help excrete phosphorus, but eventually fails as GFR declines. * **Rule of Thumb:** If Phosphorus is **High**, think Renal Failure or Hypoparathyroidism. If Phosphorus is **Low**, think Rickets or PHP.

Question 99: A 2-week-old baby presents with scrotal pigmentation, hyponatremia, hypoglycemia, and hyperkalemia. Which enzyme deficiency is most likely responsible?

A. 11 beta hydroxylase
B. 21 alpha hydroxylase (Correct Answer)
C. 3 beta hydroxylase dehydrogenase
D. 17 alpha hydroxylase

Explanation: This clinical scenario describes the classic presentation of **Congenital Adrenal Hyperplasia (CAH)**, specifically the **salt-wasting form**. ### **Explanation of the Correct Answer** **21-alpha hydroxylase deficiency** is the most common cause of CAH (>90% of cases). This enzyme is essential for converting precursors into cortisol and aldosterone. * **Aldosterone deficiency:** Leads to "salt-wasting" (hyponatremia and hyperkalemia). * **Cortisol deficiency:** Leads to hypoglycemia and a lack of negative feedback on the pituitary, causing increased ACTH. * **Hyperpigmentation:** Elevated ACTH levels cross-react with melanocortin receptors (due to the shared precursor POMC), leading to scrotal/skin pigmentation. * **Androgen excess:** Shunting of precursors into the androgen pathway causes virilization (ambiguous genitalia in females; subtle macrogenitosomia in males). ### **Why Other Options are Incorrect** * **11-beta hydroxylase deficiency:** While it causes virilization and pigmentation, it leads to **hypertension** (not salt-wasting) because the precursor 11-deoxycorticosterone (DOC) acts as a potent mineralocorticoid, retaining sodium. * **3-beta hydroxysteroid dehydrogenase deficiency:** This is rare and affects all classes of steroids. It typically presents with salt-wasting but results in **incomplete virilization** in males (ambiguous genitalia) because it blocks the formation of potent testosterone. * **17-alpha hydroxylase deficiency:** This leads to increased mineralocorticoids (**hypertension/hypokalemia**) and a total lack of sex hormones, resulting in phenotypically female infants regardless of genetic sex. ### **NEET-PG High-Yield Pearls** * **Gold Standard Diagnosis:** Elevated **17-hydroxyprogesterone (17-OHP)** levels. * **Karyotyping:** Essential in female infants with ambiguous genitalia to differentiate CAH from other DSDs. * **Management:** Acute crisis requires IV saline and hydrocortisone; long-term therapy involves glucocorticoid and mineralocorticoid (Fludrocortisone) replacement. * **Mnemonic:** If the enzyme starts with **1** (11, 17), it causes **Hypertension**. If it ends with **1** (11, 21), it causes **Virilization**.

Question 100: Screening of neonatal thyroid disease is done by?

A. T4
B. T3
C. TSH (Correct Answer)
D. TPO antibodies

Explanation: **Explanation:** **Congenital Hypothyroidism (CH)** is one of the most common preventable causes of intellectual disability. Screening is essential because most affected newborns appear clinically normal at birth due to the protective effect of maternal thyroxine. **Why TSH is the Correct Answer:** In most global screening programs, including those in India, **TSH (Thyroid Stimulating Hormone)** is the preferred primary screening tool. 1. **Sensitivity:** TSH is highly sensitive for detecting **Primary Congenital Hypothyroidism** (the cause in >95% of cases), as even a slight drop in T4 leads to a significant compensatory rise in TSH. 2. **Cost-effectiveness:** It is easier to standardize and more cost-effective than measuring free T4. 3. **Timing:** Samples are ideally collected via heel prick (Guthrie card) between **48–72 hours of life** to avoid the physiological "TSH surge" that occurs immediately after birth. **Why Other Options are Incorrect:** * **T4:** While some programs use a "Primary T4 with reflex TSH" approach, T4 alone misses cases of mild primary hypothyroidism where T4 is low-normal but TSH is elevated. * **T3:** T3 levels often remain normal until late stages of hypothyroidism and are never used for screening. * **TPO Antibodies:** These are markers for autoimmune thyroiditis (e.g., Hashimoto’s), which is an acquired condition and not a cause of congenital hypothyroidism. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of CH:** Thyroid Dysgenesis (Ectopy is the most common specific type). * **Most common cause of Goitrous CH:** Dyshormonogenesis (Thyroid Peroxidase deficiency). * **Clinical Sign:** A large posterior fontanelle (>0.5 cm) at birth is an early suspicious sign. * **Treatment:** Levothyroxine (10–15 μg/kg/day) should be started immediately to prevent permanent neurocognitive impairment.

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

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Endocrine Emergencies

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