Endocrinology Practice Questions

Q: A female neonate with DiGeorge syndrome develops severe muscle cramps and convulsions soon after birth. Which of the following is the cause of convulsions in this neonate?

Hypocalcemia. **Explanation:** The correct answer is **Hypocalcemia**. **1. Why Hypocalcemia is the cause:** DiGeorge Syndrome (22q11.2 deletion syndrome) is characterized by the embryological failure of the **3rd and 4th pharyngeal pouches** to develop. This leads to **thymic hypoplasia** (causing T-cell deficiency) and **parathyroid hypoplasia**. The absence or underdevelopment of the parathyroid glands results in a deficiency of Parathyroid Hormone (PTH), leading to **hypocalcemia** and hyperphosphatemia. In neonates, severe hypocalcemia increases neuromuscular excitability, manifesting as tetany, muscle cramps, and seizures (convulsions). **2. Why the other options are incorrect:** * **Acute hemorrhagic adrenalitis (Waterhouse-Friderichsen syndrome):** This is typically associated with meningococcemia and leads to adrenal insufficiency, not a primary feature of DiGeorge syndrome. * **Hypoglycemia:** While common in neonates (especially infants of diabetic mothers or those with IUGR), it is not a direct pathological consequence of the pharyngeal pouch defects seen in DiGeorge syndrome. * **Hypokalemia:** This refers to low potassium levels. While it can cause muscle weakness, it does not typically cause the acute convulsions seen in the neonatal presentation of DiGeorge syndrome, which is classically driven by the calcium-PTH axis. **Clinical Pearls for NEET-PG:** * **CATCH-22 Mnemonic:** **C**ardiac defects (Truncus arteriosus/TOF), **A**bnormal facies, **T**hymic hypoplasia, **C**left palate, **H**ypocalcemia (due to hypoparathyroidism), and **22**q11 deletion. * **Chest X-ray:** Look for the **absence of a thymic shadow** (also seen in SCID). * **Most common cardiac defect:** Interrupted aortic arch (Type B) or Truncus Arteriosus.

Q: Which disease affects only the formation and eruption of teeth but does not cause hypoplasia?

Hyperthyroidism. **Explanation:** The correct answer is **Hyperthyroidism**. In pediatric endocrinology, thyroid hormones play a crucial role in the timing of skeletal and dental maturation. Hyperthyroidism (accelerated metabolism) leads to **premature eruption** of teeth and early loss of deciduous teeth. Because the dental enamel and dentin are already formed or follow a normal mineralization process, the disease affects the **timing and sequence** of eruption rather than the structural integrity of the tooth. Therefore, it does not cause enamel hypoplasia. **Analysis of Incorrect Options:** * **Hypoparathyroidism:** Low parathyroid hormone leads to hypocalcemia during the developmental stage of teeth. This results in structural defects, specifically **enamel hypoplasia** and delayed eruption. * **Rickets:** Vitamin D deficiency leads to impaired mineralization of bone and teeth. It is a classic cause of **enamel hypoplasia**, delayed eruption, and defects in dentin formation. * **Syphilis (Congenital):** This infection directly affects the tooth germ during morphodifferentiation. It causes significant structural deformities known as **Hutchinson’s incisors** (notched, peg-shaped) and **Mulberry molars**. **High-Yield Clinical Pearls for NEET-PG:** * **Hypothyroidism (Cretinism):** Characterized by **delayed eruption** and a thick, protruding tongue (macroglossia). * **Hypophosphatasia:** A rare metabolic bone disease where the hallmark is the **premature loss of deciduous teeth** (especially incisors) due to cementum defects. * **Enamel Hypoplasia:** Occurs only if the systemic insult (like Rickets or Hypocalcemia) happens during the **formative (calcification) stage** of the teeth. Once the crown is formed, these conditions no longer cause hypoplasia.

Q: In children, which is the most commonly recognized form of familial hyperlipidemia?

Combined hyperlipidemia. **Explanation:** **Familial Combined Hyperlipidemia (FCHL)** is the most common genetic dyslipidemia, affecting approximately 1 in 100 individuals. In the pediatric population, it is the most frequently recognized form of familial hyperlipidemia. 1. **Why Option D is Correct:** FCHL is characterized by elevated levels of **VLDL and LDL**, leading to a simultaneous increase in both triglycerides and cholesterol. The underlying pathophysiology involves the overproduction of **Apolipoprotein B-100**. It is clinically significant because it is highly atherogenic and often presents in childhood with a strong family history of premature coronary artery disease (CAD). 2. **Why Other Options are Incorrect:** * **Hypercholesterolemia (Option B):** While Familial Hypercholesterolemia (Type IIa) is well-known due to its severity and risk of early MI, its prevalence (1 in 250–500) is lower than that of FCHL. * **Hypertriglyceridemia (Option A):** Isolated familial hypertriglyceridemia is less common in children and often remains asymptomatic until adulthood. * **Hyperchylomicronemia (Option C):** This is a rare autosomal recessive disorder (Type I) characterized by a deficiency in Lipoprotein Lipase (LPL). While it presents in infancy with eruptive xanthomas or pancreatitis, it is much rarer than FCHL. **High-Yield Pearls for NEET-PG:** * **Most common cause of pediatric dyslipidemia:** Obesity/Metabolic Syndrome (Secondary); **FCHL** (Primary/Genetic). * **Apo B-100:** The hallmark marker for FCHL. * **Clinical Presentation:** Unlike Familial Hypercholesterolemia, FCHL rarely presents with xanthomas in childhood; diagnosis usually relies on lipid profiles and family history. * **Screening:** Universal lipid screening is recommended by the AAP between ages 9–11 years.

Q: All of the following may occur in Noonan's syndrome except?

Infertility in females. **Explanation:** Noonan’s syndrome is often referred to as the **"Male Turner Syndrome"** because it shares several phenotypic features with Turner syndrome (short stature, webbed neck, cubitus valgus) but affects both males and females and is caused by mutations in the RAS-MAPK signaling pathway (most commonly the **PTPN11 gene**). **Why Option C is the correct answer:** In Noonan’s syndrome, **females typically have normal pubertal development and are fertile.** In contrast, males frequently exhibit cryptorchidism (undescended testes), which can lead to Sertoli cell dysfunction and impaired spermatogenesis, often resulting in male infertility. This is a high-yield distinction from Turner syndrome (45,XO), where females have streak ovaries and are almost always infertile. **Analysis of incorrect options:** * **A. Hypertrophic cardiomyopathy (HCM):** This is the most common cardiac muscle disease in Noonan’s (seen in ~20-30%). However, the most common overall cardiac defect is **Pulmonary Stenosis** (dysplastic valve). * **B. Cryptorchidism:** This is a hallmark feature in males with Noonan’s syndrome, occurring in up to 80% of cases. * **D. Autosomal dominant transmission:** Noonan’s syndrome is an autosomal dominant condition, though many cases arise from *de novo* mutations. **NEET-PG High-Yield Pearls:** * **Genetics:** Most common gene involved is **PTPN11** (Chromosome 12). It is part of the "RASopathies." * **Cardiac:** Pulmonary Stenosis (Most common) > HCM > ASD. * **Hematology:** Increased risk of **Juvenile Myelomonocytic Leukemia (JMML)** and bleeding diathesis (Factor XI deficiency). * **Facies:** Triangular face, hypertelorism, downward-slanting palpebral fissures, and low-set posteriorly rotated ears.

Q: Central precocious puberty in a girl is defined as breast development before what age?

8 years. **Explanation:** **1. Why Option B is Correct:** Precocious puberty is defined as the onset of secondary sexual characteristics at an age that is **more than 2.5 standard deviations (SD) below the mean** for the population. In girls, the first sign of puberty is typically **thelarche** (breast development). The globally accepted clinical cutoff for precocious puberty in girls is the development of breast tissue before the age of **8 years**. In boys, the cutoff is the enlargement of testes (volume >4 ml) before the age of 9 years. **2. Why Other Options are Incorrect:** * **Option A (6 years):** While some studies suggest that breast development in African-American or obese girls may start earlier without pathology, 6 years is too restrictive and would miss many cases of pathological precocity. * **Option D (10 years):** This is within the normal range for the onset of puberty. The average age for thelarche is approximately 10–10.5 years. * **Option C (12 years):** This is near the average age of **menarche** (first menstruation), which typically occurs 2–2.5 years after thelarche. **3. NEET-PG High-Yield Pearls:** * **Central vs. Peripheral:** Central Precocious Puberty (CPP) is **GnRH-dependent** (isosexual), while Peripheral is GnRH-independent. * **Etiology:** In girls, CPP is most commonly **Idiopathic** (80-90%). In boys, CPP is more likely to be due to an **organic CNS lesion** (e.g., hypothalamic hamartoma). * **Bone Age:** A key diagnostic step; bone age is typically **advanced** in precocious puberty. * **Treatment of Choice:** Long-acting **GnRH agonists** (e.g., Leuprolide) are used to desensitize the pituitary and halt progression to preserve final adult height.

Q: A 7-year-old girl presents with bowing of legs and difficulty walking. Her height is below average for her age group, and a sibling experiences similar issues. X-ray examination reveals metaphyseal widening and funnel-like beaking of the metaphyses. Investigations show a serum calcium of 9 mg/dL and serum phosphorus of 2.5 mg/dL. What is the most likely cause?

Hypophosphatemic rickets. ### Explanation **Correct Answer: B. Hypophosphatemic Rickets** The clinical presentation of bowing of legs, short stature, and a positive family history (sibling affected) strongly suggests **X-linked Hypophosphatemic Rickets (XLH)**, the most common form of heritable rickets. The biochemical hallmark of this condition is **isolated low serum phosphorus** with **normal serum calcium** and normal-to-low Vitamin D levels. The pathophysiology involves a defect in the *PHEX* gene, leading to increased levels of **FGF-23**, which causes renal phosphate wasting and inhibits the activation of Vitamin D. Radiologically, the "funnel-like beaking" of the metaphyses is a classic description of the metaphyseal changes seen in rickets. **Why other options are incorrect:** * **Nutritional Rickets:** Typically presents with **low or low-normal serum calcium** and significantly elevated PTH. It usually responds to Vitamin D supplementation, whereas hypophosphatemic rickets is "Vitamin D resistant." * **Azotemic Renal Osteodystrophy:** This occurs in the setting of chronic kidney disease. It is characterized by **high serum phosphorus** (due to decreased renal excretion) and low calcium, which contradicts the laboratory findings in this case. * **Primary Hyperparathyroidism:** While this causes low phosphorus, it is characterized by **hypercalcemia** (high serum calcium), whereas this patient has a normal calcium level (9 mg/dL). **High-Yield Pearls for NEET-PG:** * **Biochemical Triad of XLH:** Low Phosphorus + Normal Calcium + High/Normal Alkaline Phosphatase. * **Inheritance:** Most commonly X-linked Dominant. * **Treatment:** Oral phosphate supplements and Calcitriol (active Vitamin D). * **Key Differentiator:** Unlike nutritional rickets, there is **no** myopathy or tetany in hypophosphatemic rickets because serum calcium remains normal.

Question 1

What is the best management for hypoglycemia in a girl child with Congenital adrenal hyperplasia?

Accepted Answer

Hydrocortisone

Answer

Betamethasone

Answer

Beclomethasone

Answer

Budesonide

Question 2

A female neonate with DiGeorge syndrome develops severe muscle cramps and convulsions soon after birth. Which of the following is the cause of convulsions in this neonate?

Accepted Answer

Hypocalcemia

Answer

Acute hemorrhagic adrenalitis

Answer

Hypoglycemia

Answer

Hypokalemia

Question 3

In children with type 1 diabetes mellitus, when is ophthalmologic evaluation indicated?

Accepted Answer

After 5 years

Answer

At the time of diagnosis

Answer

After 1 year

Answer

After 2 years

Question 4

Which disease affects only the formation and eruption of teeth but does not cause hypoplasia?

Accepted Answer

Hyperthyroidism

Answer

Hypoparathyroidism

Answer

Rickets

Answer

Syphilis

Question 5

In children, which is the most commonly recognized form of familial hyperlipidemia?

Accepted Answer

Combined hyperlipidemia

Answer

Hypertriglyceridemia

Answer

Hypercholesterolemia

Answer

Hyperchylomicronemia

Question 6

A baby is born with ambiguous genitalia. Which of the following statements is true?

Accepted Answer

It is sometimes associated with a history of a previous sibling with congenital adrenal hyperplasia (CAH).

Answer

A karyotype is rarely needed.

Answer

Evaluation should be done by 1 month of age.

Answer

A thorough physical examination can usually decide the true sex.

Question 7

A 4-week-old female child with normal genitalia presents to the emergency department with severe dehydration, hyperkalemia, and hyponatremia. The measurement of which of the following blood levels will be helpful?

Accepted Answer

Aldosterone

Answer

17-hydroxyprogesterone

Answer

Renin

Answer

Cortisol

Question 8

All of the following may occur in Noonan's syndrome except?

Accepted Answer

Infertility in females

Answer

Hypertrophic cardiomyopathy

Answer

Cryptorchidism

Answer

Autosomal dominant transmission

Question 9

Central precocious puberty in a girl is defined as breast development before what age?

Accepted Answer

8 years

Answer

6 years

Answer

12 years

Answer

10 years

Question 10

A 7-year-old girl presents with bowing of legs and difficulty walking. Her height is below average for her age group, and a sibling experiences similar issues. X-ray examination reveals metaphyseal widening and funnel-like beaking of the metaphyses. Investigations show a serum calcium of 9 mg/dL and serum phosphorus of 2.5 mg/dL. What is the most likely cause?

Accepted Answer

Hypophosphatemic rickets

Answer

Nutritional rickets

Answer

Azotemic renal osteodystrophy

Answer

Primary hyperparathyroidism

Endocrinology — MCQs

Endocrinology — MCQs

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