Endocrinology Practice Questions

Q: Hypoglycemia in late infant and child occurs if blood glucose level is:

40 mg/dl. **Explanation:** The definition of hypoglycemia in the pediatric population varies based on age and clinical context. For **late infants and children**, hypoglycemia is clinically defined as a blood glucose level **<40 mg/dl**. This threshold is critical because it represents the level at which neuroglycopenic symptoms typically manifest and where immediate intervention is required to prevent neurological damage. * **Option A (40 mg/dl):** This is the standard diagnostic cutoff for hypoglycemia in children beyond the immediate neonatal period. While some guidelines suggest maintaining levels above 60-70 mg/dl in diabetic patients, 40 mg/dl remains the classic academic definition for the general pediatric population in competitive exams. * **Option B (60 mg/dl):** This is often considered the "lower limit of normal" for fasting glucose, but it does not define clinical hypoglycemia in a healthy child. * **Options C & D (10 & 20 mg/dl):** These levels represent **severe, life-threatening hypoglycemia**. While a child with these levels is certainly hypoglycemic, these values are far below the diagnostic threshold. **High-Yield Clinical Pearls for NEET-PG:** 1. **Neonatal Period:** The definition is more controversial. Generally, <40 mg/dl in the first 24 hours and <50 mg/dl thereafter is considered hypoglycemic in newborns. 2. **Whipple’s Triad:** Diagnosis of hypoglycemia syndromes requires: (1) Symptoms consistent with hypoglycemia, (2) Low plasma glucose concentration, and (3) Relief of symptoms after glucose administration. 3. **Ketotic Hypoglycemia:** The most common cause of hypoglycemia in toddlers (usually aged 18 months to 5 years), typically occurring after a period of fasting or illness. 4. **Critical Sample:** When hypoglycemia is documented, always draw a "critical sample" (Insulin, Growth Hormone, Cortisol, and Ketones) before correcting the glucose to identify the underlying etiology.

Q: What are the common clinical features of Turner syndrome?

Edema of hands and feet. **Explanation:** Turner Syndrome (45,XO) is the most common cause of primary amenorrhea and results from complete or partial monosomy of the X chromosome. **Why Option B is Correct:** **Lymphedema of the hands and feet** is a classic clinical feature, especially in neonates. It occurs due to congenital hypoplasia or malformation of the lymphatic system. In addition to peripheral edema, this lymphatic dysfunction often manifests as a **cystic hygroma** or a **webbed neck** (pterygium colli) in older children. **Why the other options are incorrect:** * **Option A:** Turner syndrome typically presents with **Primary Amenorrhea** due to "streak ovaries" (accelerated oocyte atresia). While secondary amenorrhea can occur in mosaic forms (e.g., 45,X/46,XX), primary amenorrhea is the hallmark. * **Option C:** The genotype is **45,XO** (monosomy). An XY genotype is seen in Swyer syndrome or Androgen Insensitivity Syndrome. * **Option D:** **Intelligence is usually normal** in Turner syndrome. While there may be specific learning disabilities (e.g., visuospatial tasks), generalized mental retardation is not a characteristic feature, unlike in autosomal trisomies (e.g., Down syndrome). **High-Yield Clinical Pearls for NEET-PG:** * **Short Stature:** The most consistent clinical finding (due to loss of the *SHOX* gene). * **Cardiac Anomalies:** Bicuspid aortic valve (most common) and Coarctation of the aorta. * **Renal Anomalies:** Horseshoe kidney. * **Hormonal Profile:** Hypergonadotropic hypogonadism (High FSH/LH, Low Estrogen). * **Ultrasound:** Increased Nuchal Translucency (NT) in the first trimester.

Q: True about Laron dwarfism is:

Growth hormone insensitivity. **Explanation:** **Laron Syndrome (Laron Dwarfism)** is an autosomal recessive condition characterized by severe short stature due to **Growth Hormone (GH) insensitivity**. 1. **Why Option B is Correct:** The primary defect in Laron syndrome is a mutation in the **Growth Hormone Receptor (GHR)** gene. Although the pituitary gland secretes GH normally (or even in excess), the peripheral tissues cannot respond to it. This failure of GH to bind to its receptor leads to a failure in the production of **Insulin-like Growth Factor-1 (IGF-1)**, which is the mediator of GH's growth-promoting effects. 2. **Why Other Options are Incorrect:** * **Option A:** GH levels are typically **elevated or normal**, not deficient. The body attempts to compensate for the perceived lack of GH action by secreting more. * **Option C:** Plasma **IGF-1 is markedly decreased**, not increased. Since the GH receptor is defective, the liver cannot synthesize IGF-1. * **Option D:** Plasma **IGF-BP3 (and GHBP) levels are low**. IGF-BP3 is GH-dependent; without functional GH signaling, its levels fall significantly. **High-Yield Clinical Pearls for NEET-PG:** * **Phenotype:** Patients present with "doll-like" facies, prominent forehead, small chin, high-pitched voice, and truncal obesity. * **Biochemical Hallmark:** High GH + Low IGF-1. * **Metabolic Feature:** Recurrent **fasting hypoglycemia** (due to the lack of the counter-regulatory effects of IGF-1/GH). * **Treatment:** Recombinant human **IGF-1 (Mecasermin)**. Exogenous GH is ineffective because the receptors are non-functional. * **Unique Fact:** Interestingly, individuals with Laron syndrome show a striking **resistance to cancer and Type 2 diabetes**.

Q: What is the recommended screening time for neonatal hypothyroidism after birth?

2-4 days after birth. **Explanation:** The primary goal of screening for Congenital Hypothyroidism (CH) is to detect the condition early to prevent irreversible intellectual disability. **Why 2-4 days (48-96 hours) is the correct timing:** Immediately after birth, there is a physiological **"TSH surge"** caused by the cold stress of delivery. TSH levels peak within 30–60 minutes of birth and remain high for the first 24–48 hours. If screening is performed during this window, it leads to a high rate of **false-positive** results. Waiting until 48–96 hours allows TSH levels to stabilize, ensuring that an elevated TSH is truly indicative of hypothyroidism rather than a transient neonatal surge. **Analysis of Incorrect Options:** * **Options C & D (1-4 hours):** These are incorrect because they coincide with the peak of the physiological TSH surge, leading to inaccurate results. * **Option A (1-2 days):** While some programs screen after 24 hours to facilitate early discharge, the risk of false positives remains higher than the 2-4 day window. **High-Yield Clinical Pearls for NEET-PG:** * **Most Common Cause:** Thyroid dysgenesis (Ectopy is the most common specific type). * **Clinical Presentation:** Most neonates are **asymptomatic** at birth due to maternal T4 crossing the placenta. Early signs include a large posterior fontanelle, prolonged jaundice, hoarse cry, and umbilical hernia. * **Treatment Goal:** Start Levothyroxine (10-15 μg/kg/day) within the first **2 weeks** of life to ensure normal neurodevelopment. * **Sample Collection:** Capillary blood via **heel prick** onto a Guthrie card (filter paper).

Q: What is the most common cause of congenital hypothyroidism?

Thyroid dysgenesis. **Explanation:** **Thyroid dysgenesis** is the most common cause of congenital hypothyroidism (CH), accounting for approximately **80–85% of cases**. It refers to a developmental abnormality of the thyroid gland, which includes: * **Ectopy:** The most common form (the gland is usually at the base of the tongue). * **Aplasia:** Complete absence of the gland. * **Hypoplasia:** An underdeveloped gland in the normal location. **Analysis of Incorrect Options:** * **Option C (Defective hormone synthesis):** Also known as **Dysmhorgonogenesis**, this accounts for about 10–15% of cases. It is typically inherited in an autosomal recessive pattern (e.g., TPO deficiency) and often presents with a goiter. * **Options A & D (Antithyroid drugs & Excessive iodine):** These are causes of **transient congenital hypothyroidism**. Maternal intake of drugs like methimazole or excessive iodine (povidone-iodine exposure) can temporarily suppress the fetal thyroid, but these are not the "most common" causes. **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Presentation:** Most neonates are asymptomatic at birth due to maternal T4 transfer. Early signs include a large posterior fontanelle, prolonged physiological jaundice, umbilical hernia, and a hoarse cry. * **Screening:** The best time for screening is **48–72 hours after birth** to avoid the physiological TSH surge. * **Management:** Levothyroxine is the treatment of choice. To prevent permanent neurocognitive impairment (Cretinism), treatment must be started within the **first 2 weeks of life**. * **Imaging:** Technetium-99m pertechnetate scan or Ultrasound is used to differentiate dysgenesis from dyshormonogenesis.

Q: Mental retardation is not typically seen in which of the following conditions?

Hypopituitarism. **Explanation:** The core concept tested here is the role of specific hormones and insults in neurodevelopment. **Hypopituitarism** (Option C) typically involves deficiencies in Growth Hormone (GH), ACTH, TSH, and Gonadotropins. While GH is essential for linear growth and metabolic functions, it is **not required for brain development** or cognitive function. Children with isolated GH deficiency or panhypopituitarism usually have normal intelligence, though they may experience delayed physical milestones and "doll-like" facial features. **Why the other options are incorrect:** * **Down Syndrome (Option A):** This is the most common chromosomal cause of intellectual disability (mental retardation). It is characterized by varying degrees of cognitive impairment due to trisomy 21. * **Cretinism (Option B):** Congenital hypothyroidism is a leading cause of *preventable* mental retardation. Thyroid hormones (T3/T4) are critical for neuronal migration, myelination, and synaptic connectivity during the first two years of life. * **Birth Asphyxia (Option D):** Hypoxic-Ischemic Encephalopathy (HIE) resulting from birth asphyxia leads to permanent neuronal damage. It is a major cause of cerebral palsy and associated intellectual disability. **High-Yield Clinical Pearls for NEET-PG:** 1. **GH vs. Thyroid:** GH deficiency causes "Short Stature with Normal IQ"; Thyroid deficiency causes "Short Stature with Low IQ." 2. **Laron Syndrome:** A type of GH insensitivity characterized by very short stature but normal intelligence. 3. **Bone Age:** In both Hypothyroidism and Hypopituitarism, bone age is significantly delayed compared to chronological age. 4. **Micropenis:** In a neonate, the triad of hypoglycemia, jaundice, and micropenis strongly suggests Congenital Hypopituitarism.

Q: What is the most common cause of peripheral precocious puberty in males?

Congenital adrenal hyperplasia. **Explanation:** Precocious puberty is defined as the onset of secondary sexual characteristics before age 9 in boys. It is divided into **Central (GnRH-dependent)** and **Peripheral (GnRH-independent)** types. **1. Why Congenital Adrenal Hyperplasia (CAH) is correct:** In males, peripheral precocious puberty is characterized by virilization (pubic hair, phallic enlargement) without a corresponding increase in testicular volume (testes remain prepubertal, <4ml). **Congenital Adrenal Hyperplasia (specifically 21-hydroxylase deficiency)** is the most common cause. It leads to an overproduction of adrenal androgens, which bypasses the Hypothalamic-Pituitary-Gonadal (HPG) axis, causing "isosexual" precocity. **2. Analysis of Incorrect Options:** * **Constitutional (Option B):** This refers to "Constitutional Delay," which is a variation of normal growth leading to *late* puberty, not precocious puberty. * **Klinefelter's syndrome (Option C):** This is a chromosomal anomaly (47, XXY) typically associated with *delayed* puberty and hypergonadotropic hypogonadism, not precocity. * **CNS Pathology (Option D):** CNS lesions (e.g., hypothalamic hamartomas) are the most common cause of **Central** (True) precocious puberty in males, where the HPG axis is activated early, leading to increased testicular volume. **High-Yield Clinical Pearls for NEET-PG:** * **Testicular Volume Rule:** In precocious puberty, if testes are **enlarged** (>4ml), think **Central** causes. If testes are **small/prepubertal**, think **Peripheral** (Adrenal) causes. * **Exception:** In CAH, if ectopic adrenal rests are present in the testes, they may appear enlarged, but this is rare. * **McCune-Albright Syndrome:** A classic cause of peripheral precocity in girls (triad of café-au-lait spots, polyostotic fibrous dysplasia, and autonomous endocrine function).

Question 1

Hypoglycemia in late infant and child occurs if blood glucose level is:

Accepted Answer

40 mg/dl

Answer

60 mg/dl

Answer

10 mg/dl

Answer

20 mg/dl

Question 2

A 36-year-old G2 P1 woman at 10 weeks gestation presents for an antenatal visit. Her first child, a female, was born with ambiguous genitalia and died at 6 months of age due to a metabolic problem. How would you counsel this patient regarding the risk of having a child with ambiguous genitalia in this pregnancy?

Accepted Answer

There is a one in four chance of having a child with the same disability.

Answer

There is no risk of having an affected child in subsequent pregnancies.

Answer

The risk of having an affected child is doubled.

Answer

This pregnancy is unaffected, but future pregnancies carry a high risk.

Question 3

What are the common clinical features of Turner syndrome?

Accepted Answer

Edema of hands and feet

Answer

Secondary amenorrhea

Answer

XY genotype

Answer

Mental retardation is common

Question 4

True about Laron dwarfism is:

Accepted Answer

Growth hormone insensitivity

Answer

Growth hormone deficiency

Answer

Plasma IGF-1 is markedly increased

Answer

Plasma IGF-BP3 at normal levels

Question 5

What is the recommended screening time for neonatal hypothyroidism after birth?

Accepted Answer

2-4 days after birth

Answer

1-2 days after birth

Answer

1-2 hours after birth

Answer

2-4 hours after birth

Question 6

What is the most common cause of congenital hypothyroidism?

Accepted Answer

Thyroid dysgenesis

Answer

Antithyroid drugs

Answer

Defective hormone synthesis

Answer

Excessive iodine consumption

Question 7

A newborn with ambiguous genitalia and a 46,XY karyotype develops vomiting, low serum sodium concentration, and high serum potassium. Which of the following enzymes is most likely to be abnormal?

Accepted Answer

21-hydroxylase

Answer

An enzyme involved in ovarian development

Answer

5a-reductase

Answer

An androgen receptor

Question 8

Mental retardation is not typically seen in which of the following conditions?

Accepted Answer

Hypopituitarism

Answer

Down syndrome

Answer

Cretinism

Answer

Birth asphyxia

Question 9

What is the most common cause of peripheral precocious puberty in males?

Accepted Answer

Congenital adrenal hyperplasia

Answer

Constitutional

Answer

Klinefelter's syndrome

Answer

CNS pathology

Question 10

Pseudohermaphroditism in a female child is most commonly due to which of the following enzymatic deficiencies?

Accepted Answer

21-hydroxylase deficiency

Answer

17-hydroxylase deficiency

Answer

11-hydroxylase deficiency

Answer

3-hydroxylase deficiency

Endocrinology — MCQs

Endocrinology — MCQs

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