Endocrinology Practice Questions

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: 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: Precocious puberty is defined as all of the following except?

Menstruation before age of 8 years.. **Explanation:** Precocious puberty refers to the onset of secondary sexual characteristics earlier than the statistically normal age (typically defined as >2.5 standard deviations below the mean). **Why Option C is the Correct Answer:** Precocious puberty in females is defined by the onset of breast development (Thelarche) before **8 years** of age. However, menstruation (Menarche) is a late event in the pubertal sequence. The specific definition for **precocious menarche** is the onset of menstruation before the age of **9 or 10 years** (depending on the textbook, but definitely not 8). Therefore, stating that menstruation before 8 years is the definition is incorrect, making it the "except" choice. **Analysis of Other Options:** * **Option B & D:** These represent the standard diagnostic thresholds. Precocious puberty is defined as breast budding (Tanner Stage 2) before **8 years in girls** and testicular enlargement (>4ml volume) before **9 years in boys**. * **Option A:** As mentioned, menarche before age 10 is considered precocious. While thelarche is the usual first sign, isolated menarche before age 10 warrants investigation. **High-Yield Clinical Pearls for NEET-PG:** * **Sequence in Girls:** Thelarche (Breast) → Adrenarche/Pubarche (Hair) → Growth Spurt → Menarche. * **Sequence in Boys:** Testicular enlargement (First sign) → Penile growth → Pubarche. * **Central vs. Peripheral:** Central precocious puberty (GnRH dependent) is **isosexual** and follows the normal sequence; it is most commonly **idiopathic in girls** but often due to **CNS lesions in boys**. * **McCune-Albright Syndrome:** Triad of precocious puberty, café-au-lait spots (Coast of Maine), and polyostotic fibrous dysplasia.

Q: Delayed eruption of teeth is seen in which of the following conditions?

All of the above. **Explanation:** Delayed eruption of teeth is a significant clinical marker in pediatric endocrinology and nutrition, generally defined when the first tooth does not appear by **13 months of age**. **1. Underlying Medical Concept:** Tooth eruption is a complex process involving bone remodeling and hormonal regulation. Deficiencies in hormones or nutrients essential for bone mineralization and cellular metabolism lead to a delay in this process. **2. Analysis of Options:** * **Hypovitaminosis (specifically Vitamin D):** Vitamin D is crucial for calcium and phosphate homeostasis. Deficiency (Rickets) leads to poor mineralization of the alveolar bone and dental tissues, significantly delaying eruption. * **Hypothyroidism:** Thyroid hormones are essential for skeletal maturation and linear growth. In congenital or juvenile hypothyroidism, there is a generalized delay in bone age and a marked retardation in the eruption of both deciduous and permanent teeth. * **Hypoparathyroidism:** Low levels of Parathyroid Hormone (PTH) lead to hypocalcemia. This disruption in calcium metabolism interferes with the normal eruptive path and can cause developmental defects like enamel hypoplasia and delayed eruption. **3. High-Yield Clinical Pearls for NEET-PG:** * **Most common cause:** Idiopathic/Familial is the most common cause of delayed eruption. * **Endocrine causes:** Apart from the above, **Growth Hormone deficiency (Hypopituitarism)** also causes delayed eruption. * **Genetic Syndromes:** **Cleidocranial dysplasia** (characterized by multiple supernumerary teeth and absent clavicles) and **Down Syndrome** are high-yield associations with delayed eruption. * **Mnemonic:** Remember **"CHID"** for delayed eruption: **C**leidocranial dysplasia/Cretinism, **H**ypothyroidism/Hypopituitarism, **I**diopathic, **D**own syndrome/Vitamin **D** deficiency.

Q: Sweat chloride levels are increased in all of the following conditions except?

Obesity. **Explanation:** The sweat chloride test is the gold standard for diagnosing Cystic Fibrosis (CF), but several other conditions can cause false-positive elevations. **1. Why Obesity is the Correct Answer:** Obesity is **not** associated with increased sweat chloride levels. In fact, there is no physiological mechanism linking increased adipose tissue to altered electrolyte transport in the eccrine glands. Therefore, it does not interfere with the interpretation of a sweat chloride test. **2. Analysis of Incorrect Options (Conditions with Elevated Sweat Chloride):** * **Cystic Fibrosis (Option A):** The primary cause. A defect in the CFTR protein prevents chloride reabsorption in sweat ducts, leading to levels >60 mmol/L. * **G-6-PD Deficiency (Option B):** This is a recognized metabolic cause of false-positive sweat chloride tests, likely due to alterations in the metabolic pathways of the sweat gland cells. * **Hereditary Nephrogenic Diabetes Insipidus (Option C):** This condition can cause elevated sweat chloride levels due to chronic volume depletion and secondary hyperaldosteronism, which affects electrolyte handling. **3. High-Yield Clinical Pearls for NEET-PG:** Other important conditions causing **False Positive** Sweat Chloride tests (High-yield for exams): * **Endocrine:** Untreated Adrenal Insufficiency (Addison’s), Hypothyroidism, Pseudohypoaldosteronism. * **Metabolic:** Galactosemia, Mucopolysaccharidosis, Fucosidosis. * **Nutritional/Other:** Protein-energy malnutrition (PEM), Ectodermal dysplasia, Anorexia nervosa. **Diagnostic Thresholds for CF:** * **Normal:** ≤29 mmol/L * **Intermediate:** 30–59 mmol/L (Requires repeat testing or genetic analysis) * **Abnormal (CF Likely):** ≥60 mmol/L

Question 1

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 2

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 3

A 2-month-old boy is evaluated for failure to thrive. The child experiences a seizure during examination. Physical examination reveals hepatomegaly, confirmed by CT scan, which also shows renomegaly. Serum chemistries demonstrate severe hypoglycemia, hyperlipidemia, lactic acidosis, and ketosis. Which of the following diseases best accounts for this presentation?

Accepted Answer

Von Gierke's disease

Answer

Gaucher's disease

Answer

McArdle's disease

Answer

Niemann-Pick disease

Question 4

Which of the following is NOT a clinical manifestation of Marfan syndrome?

Accepted Answer

Mental retardation

Answer

Corneal opacity

Answer

Stunted growth

Answer

Absent clavicle

Question 5

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 6

A 30-year-old pregnant woman and her 2-year-old child reside in a high-altitude area. The child presents with short stature, a potbelly, an enlarged protruding tongue, and developmental delay. Iodine supplementation is initiated for both mother and child to prevent mental retardation in the developing fetus. All statements regarding iodide oxidation are true EXCEPT:

Accepted Answer

Iodide transported to the follicular lumen by Na-I symporter

Answer

Conversion of iodide to iodine

Answer

Promoted by the enzyme peroxidase

Answer

Propylthiouracil blocks this step

Question 7

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 8

Precocious puberty is defined as all of the following except?

Accepted Answer

Menstruation before age of 8 years.

Answer

Onset of menstruation before age of 10 years.

Answer

Appearance of breast budding before age of 8 years in females.

Answer

Puberty occurring before 9 years in males.

Question 9

Delayed eruption of teeth is seen in which of the following conditions?

Accepted Answer

All of the above

Answer

Hypovitaminosis

Answer

Hypothyroidism

Answer

Hypoparathyroidism

Question 10

Sweat chloride levels are increased in all of the following conditions except?

Accepted Answer

Obesity

Answer

Cystic fibrosis

Answer

G-6-PD deficiency

Answer

Hereditary nephrogenic diabetes insipidus

Endocrinology — MCQs

Endocrinology — MCQs

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