Endocrinology Practice Questions

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.

Q: Which of the following is NOT typically seen in congenital hypothyroidism?

Short metacarpals. **Explanation:** Congenital Hypothyroidism (CH) is one of the most common treatable causes of intellectual disability. The correct answer is **Short metacarpals**, as this is a characteristic feature of **Pseudohypoparathyroidism (Albright Hereditary Osteodystrophy)** or Turner Syndrome, rather than hypothyroidism. **Why the other options are seen in Congenital Hypothyroidism:** * **Delayed bone age (A):** Thyroid hormones are essential for linear growth and epiphyseal maturation. Deficiency leads to a significant lag in bone age compared to chronological age. * **Delayed puberty (B):** Thyroid hormone is required for the normal maturation of the hypothalamic-pituitary-gonadal axis. While severe juvenile hypothyroidism can rarely cause precocious puberty (Van Wyk-Grumbach syndrome), the standard presentation of untreated hypothyroidism is delayed puberty. * **Large anterior fontanelle (D):** Delayed ossification of the skull bones leads to a large anterior fontanelle and a persistently open posterior fontanelle (a key early diagnostic clue). **Clinical Pearls for NEET-PG:** * **Most common cause:** Thyroid dysgenesis (Ectopy is the most common specific type). * **Early signs:** Prolonged physiological jaundice, poor feeding, hoarse cry, and umbilical hernia. * **Late signs:** Macroglossia, "pot-bellied" appearance, and developmental delay (Cretinism). * **Radiological sign:** Absence of the distal femoral epiphysis at birth (normally appears at 36 weeks gestation) is a strong indicator of in-utero hypothyroidism. * **Treatment:** Levothyroxine (10–15 μg/kg/day) initiated as early as possible to prevent permanent neurocognitive impairment.

Q: What is the treatment for virilizing adrenal hyperplasia?

Cortisone. **Explanation:** Virilizing Adrenal Hyperplasia (Congenital Adrenal Hyperplasia - CAH) is most commonly caused by a deficiency of the enzyme **21-hydroxylase**. This deficiency leads to impaired synthesis of cortisol. Due to the lack of negative feedback from cortisol, the pituitary gland secretes excessive **ACTH**. High ACTH levels overstimulate the adrenal cortex, causing hyperplasia and shunting steroid precursors into the androgen pathway, resulting in virilization. **Why Cortisone is correct:** The primary goal of treatment is **hormone replacement**. Administering glucocorticoids (like Cortisone, Hydrocortisone, or Prednisolone) serves two purposes: 1. It replaces the deficient physiological cortisol. 2. It provides negative feedback to the pituitary to **suppress ACTH secretion**, thereby halting the overproduction of adrenal androgens and preventing further virilization. **Why other options are incorrect:** * **Estrogens:** These do not address the underlying enzyme deficiency or the ACTH excess. * **Antiandrogens:** While they may block androgen action, they do not correct the life-threatening cortisol deficiency or the adrenal hyperplasia. * **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 (90-95% of cases). * **Diagnostic Marker:** Elevated levels of **17-hydroxyprogesterone (17-OHP)**. * **Salt-wasting type:** Occurs in 75% of cases; requires additional **Mineralocorticoid** replacement (Fludrocortisone). * **Clinical Presentation:** Ambiguous genitalia in females; precocious puberty or salt-wasting crisis (hyponatremia, hyperkalemia) in males.

Q: A 6-year-old child complains of difficulty in swallowing and on examination, there is a sublingual swelling, which is suspected to be lingual thyroid. What is the first step in the management of this child?

Thyroid scan. **Explanation:** The correct answer is **Thyroid scan (Option B)**. A **lingual thyroid** is the most common form of ectopic thyroid tissue, resulting from the failure of the thyroid gland to descend from the foramen cecum to its normal pre-tracheal position during embryogenesis. In approximately **70-75% of cases**, the lingual thyroid is the **only functioning thyroid tissue** present in the body. Before any surgical intervention or biopsy, it is mandatory to perform a thyroid scan (using Technetium-99m or Iodine-123) to: 1. Confirm the presence of ectopic thyroid tissue. 2. Determine if there is any normally located thyroid tissue in the neck. Removing a lingual thyroid without checking for a normal gland would render the patient permanently hypothyroid. **Why other options are incorrect:** * **Options A & C:** Tracheostomy and intubation are emergency measures for acute airway obstruction. While a large lingual thyroid can cause dysphagia or mild respiratory distress, it rarely presents as a sudden airway emergency requiring immediate invasive procedures unless there is acute hemorrhage or severe stridor. * **Option D:** Surgery is not the immediate first step. Many patients are managed conservatively with suppressive levothyroxine therapy to shrink the gland. Surgery is reserved for severe obstruction, bleeding, or malignancy. **Clinical Pearls for NEET-PG:** * **Most common site of ectopic thyroid:** Base of the tongue (Lingual thyroid). * **Gender Predilection:** More common in females (4:1 ratio). * **Clinical Presentation:** Often asymptomatic until puberty or pregnancy (due to increased physiological demand for T4). * **Diagnosis:** Thyroid scan is the gold standard; Ultrasound of the neck is used to check for the presence of a normal gland.

Question 1

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 2

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 3

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 4

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 5

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

Question 6

Which of the following is NOT typically seen in congenital hypothyroidism?

Accepted Answer

Short metacarpals

Answer

Delayed bone age

Answer

Delayed puberty

Answer

Large anterior fontanelle

Question 7

What is the treatment for virilizing adrenal hyperplasia?

Accepted Answer

Cortisone

Answer

Estrogens

Answer

Antiandrogens

Answer

ACTH

Question 8

A child presents with obesity, short stature, hypertension, and hyperglycemia. What is the most probable diagnosis?

Accepted Answer

Cushing's syndrome

Answer

Addison's disease

Answer

Congenital disease

Answer

Congenital adrenal hyperplasia

Question 9

Delayed puberty is defined as the absence of secondary sexual characteristics by age 13 in girls and 14 in boys, or the absence of menarche by age 15. What is the age threshold for primary amenorrhea without the development of secondary sexual characters that defines delayed puberty?

Accepted Answer

16 years

Answer

12 years

Answer

14 years

Answer

18 years

Question 10

A 6-year-old child complains of difficulty in swallowing and on examination, there is a sublingual swelling, which is suspected to be lingual thyroid. What is the first step in the management of this child?

Accepted Answer

Thyroid scan

Answer

Tracheostomy and airway maintenance

Answer

Intubation

Answer

Explain to the child's parents that he may require immediate surgery

Endocrinology — MCQs

Endocrinology — MCQs

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