Endocrinology Practice Questions

Q: A 3-week-old female infant presents with ambiguous genitalia and hyperpigmentation of the skin. Laboratory findings include hyponatremia and hyperkalemia. What is the most likely diagnosis?

21 hydroxylase deficiency. ***21 hydroxylase deficiency*** - This is the most common form of Congenital Adrenal Hyperplasia (CAH) where a lack of cortisol leads to high **ACTH**, resulting in adrenal hyperplasia and skin **hyperpigmentation**. - Reduced mineralocorticoids cause **hyponatremia** and **hyperkalemia**, while shunted precursors increase androgens, causing **ambiguous genitalia** in females. *17 alpha hydroxylase deficiency* - This condition leads to a decrease in androgens and cortisol, resulting in **normal female external genitalia** but phenotypic males appearing female. - It causes an excess of mineralocorticoids, leading to **hypertension** and hypokalemia, which contradicts the laboratory findings provided. *17, 20 lyase deficiency* - This enzyme deficiency selectively impairs the production of **sex hormones** (androgens and estrogens) without affecting cortisol or aldosterone. - It does not present with **salt-wasting** (hyponatremia/hyperkalemia) or skin hyperpigmentation, as the mineralocorticoid and glucocorticoid pathways remain intact. *11 beta hydroxylase deficiency* - While this deficiency causes androgen excess and **virilization** of females, it leads to the accumulation of 11-deoxycorticosterone, a potent mineralocorticoid. - The resulting clinical picture includes **hypertension** and hypokalemia rather than the hyponatremic/hyperkalemic salt-wasting state seen in this infant.

Q: Cretinism is characterized by which of the following physical features?

Disproportionate dwarfism. **Explanation:** **Cretinism** (Congenital Hypothyroidism) results from a deficiency of thyroid hormones during fetal or neonatal life. Thyroid hormone is essential for skeletal maturation and linear growth. In its absence, there is a significant delay in bone age and the maturation of the epiphyseal centers. **Why Option A is Correct:** The hallmark of cretinism is **disproportionate dwarfism**. Thyroid hormone is critical for the growth of long bones. When deficient, the limbs remain short while the trunk continues to grow relatively more, leading to a **low upper segment to lower segment (US:LS) ratio** for the child's age (retaining the infantile proportions where the upper segment is longer). This is distinct from growth hormone deficiency, which typically causes proportionate dwarfism. **Why Other Options are Incorrect:** * **Options B & C:** These descriptions are inaccurate. While the trunk may appear "long" relative to the limbs, the standard clinical terminology is "disproportionate." Short-trunk dwarfism is more characteristic of skeletal dysplasias like Morquio syndrome. * **Option D:** Hypothyroidism leads to growth retardation, not long stature. **Clinical Pearls for NEET-PG:** * **Most common cause:** Thyroid dysgenesis (Ectopic thyroid is the most common specific etiology). * **Early signs:** Prolonged physiological jaundice, poor feeding, constipation, and a large posterior fontanelle (>0.5 cm). * **Classic triad:** Coarse facies, macroglossia (large tongue), and umbilical hernia. * **Radiology:** Absence of the distal femoral epiphysis at birth is a strong indicator of in utero hypothyroidism. * **Treatment:** Levothyroxine (T4) must be started within the first 2 weeks of life to prevent permanent intellectual disability.

Q: A mother reports that her 2-week-old infant sleeps most of the day and needs to be awakened every 4 hours for feeding, taking only one ounce of formula at a time. She is also concerned about the infant's persistently hard, pellet-like stools. Examination reveals an infant with normal weight and length, but with an enlarged head, a heart rate of 75 beats per minute, a temperature of 35°C (95°F), persistent jaundice, large anterior and posterior fontanelles, a distended abdomen, and an umbilical hernia. This clinical presentation is likely a result of which of the following?

Congenital hypothyroidism. ### Explanation **Correct Answer: A. Congenital Hypothyroidism** This infant presents with the classic "quiet baby" syndrome of **Congenital Hypothyroidism (CH)**. Thyroid hormones are essential for metabolic processes and neurological development. A deficiency leads to a generalized slowing of body functions, manifesting as: * **Metabolic slowing:** Hypothermia (35°C), bradycardia (75 bpm), and lethargy (sleeping most of the day). * **Gastrointestinal:** Decreased motility leads to constipation (hard, pellet-like stools), poor feeding, and abdominal distension. * **Structural signs:** Large anterior and posterior fontanelles (delayed bone age), umbilical hernia, and macroglossia (often causing feeding issues). * **Jaundice:** Prolonged unconjugated hyperbilirubinemia due to delayed glucuronyl transferase activity. **Why other options are incorrect:** * **B. Hirschsprung Disease:** While it causes constipation, abdominal distension, and potentially an umbilical hernia, it does **not** explain the bradycardia, hypothermia, large fontanelles, or prolonged jaundice. * **C. Sepsis:** Can cause lethargy, poor feeding, and temperature instability, but it is an acute presentation. It would not explain the large fontanelles or umbilical hernia. * **D. Infantile Botulism:** Presents with "floppy baby" syndrome (hypotonia) and constipation, but typically occurs in slightly older infants (after honey ingestion) and does not feature the structural/metabolic signs of CH. **NEET-PG High-Yield Pearls:** * **Most common cause:** Dysgenesis (Agenesis/Ectopy) of the thyroid gland. * **Most sensitive screening test:** Serum TSH (usually performed via heel prick on day 3–5). * **Clinical Clue:** A posterior fontanelle >0.5 cm in a term neonate is highly suggestive of CH. * **Treatment:** Levothyroxine (10–15 μg/kg/day). Early treatment (within 2 weeks) is critical to prevent permanent intellectual disability (Cretinism).

Q: A 13-year-old boy presents with bilateral gynecomastia. His height is 148 cm, weight is 58 kg, and his sexual maturity rating is stage 2. The gynecomastia is most likely due to what condition?

Pubertal gynecomastia. **Explanation:** **Pubertal gynecomastia** is the most common cause of breast enlargement in adolescent males, affecting up to 50–60% of boys during puberty. It typically occurs between ages 10 and 14, corresponding to **Sexual Maturity Rating (SMR/Tanner) stages 2 or 3**. The underlying pathophysiology is a **transient imbalance** between estrogen and androgen action at the breast tissue level, where estrogen levels rise earlier or more rapidly than testosterone during early puberty. In most cases, it is bilateral, benign, and resolves spontaneously within 6 to 24 months. **Why other options are incorrect:** * **Prolactinoma:** While hyperprolactinemia can cause galactorrhea, it rarely causes true gynecomastia unless it leads to secondary hypogonadism (low testosterone). * **Testicular Tumor:** Certain tumors (e.g., Leydig cell or hCG-secreting germ cell tumors) can cause gynecomastia due to excess estrogen production, but these are rare and usually present with a palpable testicular mass or rapid virilization. * **Chronic Liver Disease:** This causes gynecomastia via decreased degradation of androstenedione and increased peripheral conversion to estrogen. However, it would be accompanied by other systemic signs like jaundice, hepatosplenomegaly, or spider nevi. **NEET-PG High-Yield Pearls:** * **Peak Incidence:** Tanner Stage 2–3. * **Management:** Reassurance is the first line. Medical therapy (Tamoxifen) or surgery is only considered if it persists beyond age 17, causes severe psychological distress, or is macrogynecomastia (>5 cm). * **Drugs causing gynecomastia (Mnemonic: DISCO):** **D**igoxin, **I**soniazid, **S**pironolactone, **C**imetidine, **O**estrogens/Ketoconazole.

Q: All of the following conditions except one can lead to delayed puberty?

McCune-Albright syndrome. **Explanation:** The core concept in this question is differentiating between conditions that cause **delayed puberty** versus those that cause **precocious (early) puberty**. **Why McCune-Albright Syndrome (MAS) is the correct answer:** McCune-Albright Syndrome is a classic cause of **GnRH-independent (Peripheral) Precocious Puberty**. It is caused by a somatic mutation in the *GNAS1* gene, leading to constitutive activation of the G-protein signaling pathway. This results in autonomous overproduction of hormones. The clinical triad includes: 1. **Precocious puberty** (typically presenting as early vaginal bleeding in girls). 2. **Polyostotic fibrous dysplasia** (bony lesions). 3. **Café-au-lait spots** (irregular "Coast of Maine" borders). **Why the other options are incorrect:** * **Kallmann Syndrome:** A form of hypogonadotropic hypogonadism (low FSH/LH) due to failure of GnRH neuron migration. It presents with **delayed puberty** and anosmia. * **Turner Syndrome (45,XO):** The most common cause of primary amenorrhea and **delayed puberty** in females due to streak ovaries (hypergonadotropic hypogonadism). * **Addison Disease:** Chronic adrenal insufficiency can lead to significant systemic illness and nutritional compromise, which often results in a functional delay of the hypothalamic-pituitary-gonadal axis, leading to **delayed puberty**. **NEET-PG High-Yield Pearls:** * **Delayed Puberty Definition:** Absence of secondary sexual characteristics by age 13 in girls (thelarche) or age 14 in boys (testicular volume <4ml). * **McCune-Albright:** Look for the "Coast of Maine" café-au-lait spots. In contrast, Neurofibromatosis Type 1 has "Coast of California" (smooth) spots. * **Most common cause of delayed puberty:** Constitutional Delay of Growth and Puberty (CDGP) – often a "late bloomer" with a family history.

Q: A 7-year-old female child presents with features of precocious puberty. On examination, she exhibits signs of virilization and is hypertensive. Which of the following enzyme deficiencies is most likely responsible for her condition?

11-hydroxylase deficiency. **Explanation:** The clinical presentation of **precocious puberty (virilization)** combined with **hypertension** is the classic hallmark of **11β-hydroxylase deficiency**. **1. Why 11β-hydroxylase deficiency is correct:** In this condition, the conversion of 11-deoxycortisol to cortisol and 11-deoxycorticosterone (DOC) to corticosterone is blocked. This leads to: * **Androgen Excess:** Shunting of precursors into the androgen pathway causes virilization (ambiguous genitalia in females, precocious puberty in children). * **Hypertension:** The accumulation of **11-deoxycorticosterone (DOC)**, a potent mineralocorticoid, causes salt and water retention, leading to hypertension and hypokalemia. **2. Why other options are incorrect:** * **21-hydroxylase deficiency:** The most common cause of CAH. It causes virilization but is associated with **hypotension** (salt-wasting) due to a lack of mineralocorticoids. * **17-hydroxylase deficiency:** Leads to hypertension (excess DOC) but results in a **deficiency of sex hormones**. Patients present with delayed puberty and primary amenorrhea, not virilization. * **3β-hydroxysteroid dehydrogenase deficiency:** A rare form that causes salt-wasting (hypotension) and incomplete virilization/ambiguous genitalia in both sexes due to the accumulation of weak androgens (DHEA). **Clinical Pearls for NEET-PG:** * **Rule of "1":** If the enzyme starts with **1** (11 or 17), it causes **Hypertension**. * **Rule of "Virilization":** If the enzyme ends with **1** (11 or 21), it causes **Virilization**. * **11β-hydroxylase deficiency** = Hypertension + Virilization. * **21-hydroxylase deficiency** = Hypotension + Virilization. * **17-hydroxylase deficiency** = Hypertension + Sexual Infantilism.

Q: What is the most common enzyme deficiency leading to childhood hypertension?

11-Beta hydroxylase. **Explanation:** Congenital Adrenal Hyperplasia (CAH) results from enzymatic defects in the cortisol synthesis pathway. The correct answer is **11-Beta hydroxylase deficiency** because it is the most common cause of CAH associated with **hypertension**. **1. Why 11-Beta Hydroxylase is Correct:** In this deficiency, the conversion of 11-deoxycorticosterone (DOC) to corticosterone is blocked. This leads to a massive buildup of **11-deoxycorticosterone (DOC)**. DOC is a potent mineralocorticoid that acts like aldosterone, causing sodium retention, volume expansion, and subsequent **hypertension**. Additionally, shunting of precursors leads to excess androgens, causing virilization in females. **2. Why Other Options are Incorrect:** * **21-Beta hydroxylase (Option B):** This is the **most common overall cause of CAH** (90-95%). However, it leads to a deficiency of mineralocorticoids, resulting in **hypotension** and salt-wasting, not hypertension. * **17-Alpha hydroxylase (Option A):** While this deficiency *does* cause hypertension (due to excess DOC), it is much rarer than 11-Beta hydroxylase deficiency. Furthermore, it results in a deficiency of sex hormones, leading to delayed puberty and primary amenorrhea, rather than the virilization seen in 11-Beta. **Clinical Pearls for NEET-PG:** * **11-Beta Hydroxylase:** Think "Hypertension + Virilization." * **17-Alpha Hydroxylase:** Think "Hypertension + Sexual Infantilism/Delayed Puberty." * **21-Beta Hydroxylase:** Think "Hypotension/Salt-wasting + Virilization." * **Mnemonic:** If the enzyme starts with **1** (11 or 17), it causes **Hypertension** (the "1" looks like an elevated BP line). If it ends with **1** (11 or 21), it causes **Virilization**.

Q: Which of the following is true about Turner's syndrome?

Normal intelligence. **Explanation:** Turner’s Syndrome (45,XO) is the most common sex chromosomal abnormality in females. The correct answer is **Normal intelligence**, as the majority of individuals with Turner’s syndrome have a normal intelligence quotient (IQ), although they may occasionally exhibit specific learning disabilities related to visuospatial processing or mathematics. **Analysis of Options:** * **Normal breast development (Incorrect):** Due to **gonadal dysgenesis**, there is a lack of estrogen production. This leads to a failure of secondary sexual characteristics, resulting in poor breast development (Tanner Stage 1-2) and primary amenorrhea. * **Normal gonadal development (Incorrect):** The characteristic finding is **streak ovaries** (fibrous tissue devoid of follicles). Accelerated atresia of germ cells occurs in utero, leading to premature ovarian failure. * **Tall stature (Incorrect):** Short stature is the most consistent clinical feature of Turner’s syndrome, primarily due to the loss of the **SHOX gene** located on the distal short arm of the X chromosome. **High-Yield Clinical Pearls for NEET-PG:** * **Karyotype:** 45,XO is the most common (50%), followed by mosaicism (45,X/46,XX). * **Cardiovascular:** Bicuspid aortic valve (most common) and Coarctation of the aorta. * **Renal:** Horseshoe kidney. * **Physical Signs:** Webbed neck (pterygium colli), increased carrying angle (cubitus valgus), and shield chest with widely spaced nipples. * **Hormonal Profile:** Hypergonadotropic hypogonadism (High FSH/LH, Low Estrogen). * **Management:** Growth hormone therapy for height; Estrogen/Progesterone for secondary sexual characteristics and bone health.

Question 1

A 3-week-old female infant presents with ambiguous genitalia and hyperpigmentation of the skin. Laboratory findings include hyponatremia and hyperkalemia. What is the most likely diagnosis?

Accepted Answer

21 hydroxylase deficiency

Answer

17 alpha hydroxylase deficiency

Answer

17, 20 lyase deficiency

Answer

11 beta hydroxylase deficiency

Question 2

Cretinism is characterized by which of the following physical features?

Accepted Answer

Disproportionate dwarfism

Answer

Short stature with a long trunk

Answer

Short stature with a short trunk

Answer

Long stature with a long trunk

Question 3

What is the least common cause of ambiguous genitalia in a female genotype?

Accepted Answer

Fetal steroid sulphatase deficiency

Answer

21 hydroxylase deficiency

Answer

11 hydroxylase deficiency

Answer

WT1 gene

Question 4

A mother reports that her 2-week-old infant sleeps most of the day and needs to be awakened every 4 hours for feeding, taking only one ounce of formula at a time. She is also concerned about the infant's persistently hard, pellet-like stools. Examination reveals an infant with normal weight and length, but with an enlarged head, a heart rate of 75 beats per minute, a temperature of 35°C (95°F), persistent jaundice, large anterior and posterior fontanelles, a distended abdomen, and an umbilical hernia. This clinical presentation is likely a result of which of the following?

Accepted Answer

Congenital hypothyroidism

Answer

Congenital megacolon (Hirschsprung disease)

Answer

Sepsis

Answer

Infantile botulism

Question 5

A previously healthy 6-week-old female infant is found unresponsive in her crib. She is well-developed and well-nourished with normal blood pressure and appearance of the genitalia but has increased pigmentation of her skin. Her blood glucose level is 30 mg/dl. What is the most likely diagnosis?

Accepted Answer

Familial glucocorticoid deficiency

Answer

Congenital adrenal hyperplasia due to 21-alpha hydroxylase deficiency

Answer

Cushing syndrome

Answer

Insulinoma

Question 6

A 13-year-old boy presents with bilateral gynecomastia. His height is 148 cm, weight is 58 kg, and his sexual maturity rating is stage 2. The gynecomastia is most likely due to what condition?

Accepted Answer

Pubertal gynecomastia

Answer

Prolactinoma

Answer

Testicular tumor

Answer

Chronic liver disease

Question 7

All of the following conditions except one can lead to delayed puberty?

Accepted Answer

McCune-Albright syndrome

Answer

Kallman syndrome

Answer

Turner syndrome

Answer

Addison disease

Question 8

A 7-year-old female child presents with features of precocious puberty. On examination, she exhibits signs of virilization and is hypertensive. Which of the following enzyme deficiencies is most likely responsible for her condition?

Accepted Answer

11-hydroxylase deficiency

Answer

21-hydroxylase deficiency

Answer

17-hydroxylase deficiency

Answer

3β-hydroxysteroid dehydrogenase deficiency

Question 9

What is the most common enzyme deficiency leading to childhood hypertension?

Accepted Answer

11-Beta hydroxylase

Answer

17-Alpha hydroxylase

Answer

21-Beta hydroxylase

Answer

All

Question 10

Which of the following is true about Turner's syndrome?

Accepted Answer

Normal intelligence

Answer

Normal breast development

Answer

Normal gonadal development

Answer

Tall stature

Endocrinology — MCQs

Endocrinology — MCQs

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