Endocrinology — MCQs
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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?
What is the most common enzyme deficiency leading to childhood hypertension?
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?
Which of the following is NOT a clinical manifestation of Marfan syndrome?
Hypoglycemia in late infant and child occurs if blood glucose level is:
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:
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?
Precocious puberty is defined as all of the following except?
Delayed eruption of teeth is seen in which of the following conditions?
Sweat chloride levels are increased in all of the following conditions except?
Endocrinology Indian Medical PG Practice Questions and MCQs
Question 11: 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?
- A. 21-hydroxylase deficiency
- B. 11-hydroxylase deficiency (Correct Answer)
- C. 17-hydroxylase deficiency
- D. 3β-hydroxysteroid dehydrogenase deficiency
Explanation: **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.
Question 12: What is the most common enzyme deficiency leading to childhood hypertension?
- A. 17-Alpha hydroxylase
- B. 21-Beta hydroxylase
- C. 11-Beta hydroxylase (Correct Answer)
- D. All
Explanation: **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**.
Question 13: 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?
- A. Gaucher's disease
- B. McArdle's disease
- C. Niemann-Pick disease
- D. Von Gierke's disease (Correct Answer)
Explanation: **Explanation:** The clinical presentation of severe fasting hypoglycemia, hepatomegaly, renomegaly, and a metabolic profile of "lactic acidosis, hyperlipidemia, and hyperuricemia" is classic for **Von Gierke’s Disease (Glycogen Storage Disease Type I)**. **1. Why Von Gierke’s Disease is Correct:** This condition is caused by a deficiency of **Glucose-6-Phosphatase**, the enzyme responsible for converting Glucose-6-Phosphate into free glucose. Since this is the final common pathway for both glycogenolysis and gluconeogenesis, the liver cannot release glucose into the blood, leading to **severe fasting hypoglycemia** (often causing seizures). The accumulation of G6P shunts into alternative pathways: * **Glycogen accumulation:** Causes massive hepatomegaly and renomegaly. * **Glycolysis:** Leads to excessive pyruvate and **lactic acidosis**. * **HMP Shunt:** Increases ribose-5-phosphate, leading to hyperuricemia. * **Lipogenesis:** Causes marked **hyperlipidemia** (doll-like facies). **2. Why Incorrect Options are Wrong:** * **Gaucher’s Disease:** A lysosomal storage disease (Glucocerebrosidase deficiency). While it causes hepatosplenomegaly, it does **not** cause hypoglycemia or lactic acidosis. * **McArdle’s Disease (GSD Type V):** A muscle-specific glycogen phosphorylase deficiency. It presents in adolescence with exercise-induced cramps and myoglobinuria; it does not affect the liver or blood glucose. * **Niemann-Pick Disease:** A lysosomal storage disease (Sphingomyelinase deficiency) characterized by hepatosplenomegaly and neurodegeneration (cherry-red spot), but not metabolic hypoglycemia. **High-Yield Clinical Pearls for NEET-PG:** * **Key Triad:** Fasting hypoglycemia + Lactic acidosis + Hyperuricemia. * **Physical Sign:** "Doll-like facies" due to fat deposition in cheeks. * **Distinction:** Unlike GSD Type III (Cori disease), Von Gierke’s presents with **lactic acidosis** and **renomegaly**. * **Treatment:** Frequent feeds with uncooked cornstarch (slow-release glucose) and avoidance of fructose/galactose.
Question 14: Which of the following is NOT a clinical manifestation of Marfan syndrome?
- A. Corneal opacity
- B. Mental retardation (Correct Answer)
- C. Stunted growth
- D. Absent clavicle
Explanation: **Explanation:** Marfan syndrome is an **autosomal dominant** connective tissue disorder caused by a mutation in the **FBN1 gene** on chromosome 15, leading to defective **fibrillin-1**. **Why "Mental Retardation" is the correct answer:** Intelligence in Marfan syndrome is typically **normal**. Unlike other multisystem genetic disorders (such as Homocystinuria, which is a common differential), Marfan syndrome does not involve the central nervous system in a way that impairs cognitive development. Therefore, mental retardation is not a clinical manifestation of this syndrome. **Analysis of other options:** * **Corneal Opacity:** While ectopia lentis (superotemporal lens subluxation) is the hallmark ocular finding, other ocular complications like high myopia and retinal detachment are common. However, corneal opacity is not a classic feature; in the context of this specific (and somewhat controversial) MCQ, it is often listed as a "distractor" or a less common finding compared to the definitive absence of intellectual disability. * **Stunted Growth:** Patients with Marfan syndrome are characteristically **tall** with dolichostenomelia (long limbs). Stunted growth is the opposite of the expected phenotype. * **Absent Clavicle:** This is a hallmark of **Cleidocranial Dysplasia**, not Marfan syndrome. *Note: In many standard medical exams, this specific question is used to differentiate Marfan from Homocystinuria.* **High-Yield Clinical Pearls for NEET-PG:** 1. **Marfan vs. Homocystinuria:** Marfan has normal IQ and **upward** lens subluxation; Homocystinuria has mental retardation, thromboembolism, and **downward** lens subluxation. 2. **Cardiovascular:** The most common cause of death is **Aortic Root Dilatation** leading to aortic dissection or mitral valve prolapse (MVP). 3. **Skeletal:** Look for a positive **Steinberg sign** (thumb) and **Walker-Murdoch sign** (wrist). 4. **Genetics:** Fibrillin-1 mutation results in the overactivity of **TGF-β** signaling.
Question 15: Hypoglycemia in late infant and child occurs if blood glucose level is:
- A. 40 mg/dl (Correct Answer)
- B. 60 mg/dl
- C. 10 mg/dl
- D. 20 mg/dl
Explanation: **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.
Question 16: 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:
- A. Conversion of iodide to iodine
- B. Promoted by the enzyme peroxidase
- C. Iodide transported to the follicular lumen by Na-I symporter (Correct Answer)
- D. Propylthiouracil blocks this step
Explanation: **Explanation:** The clinical presentation of short stature, potbelly, macroglossia, and developmental delay in a child from a high-altitude (iodine-deficient) area is classic for **Congenital Hypothyroidism (Cretinism)**. The question focuses on the biochemistry of thyroid hormone synthesis. **Why Option C is the Correct Answer (The "Except" statement):** The **Sodium-Iodide (Na-I) Symporter (NIS)** is responsible for the active transport of iodide from the **blood into the thyroid follicular cell** (basolateral membrane), not into the follicular lumen. The transport of iodide from the cell across the apical membrane into the **follicular lumen** is mediated by a different transporter called **Pendrin**. **Analysis of Incorrect Options:** * **Option A:** Oxidation is chemically defined as the conversion of iodide ($I^-$) to nascent iodine ($I^0$) or $I_2$, which is essential for it to bind to tyrosine residues on thyroglobulin. * **Option B:** This oxidation step is catalyzed by the enzyme **Thyroid Peroxidase (TPO)**, located at the apical membrane. * **Option C (Incorrect statement):** As explained, NIS moves iodide into the cell; Pendrin moves it into the lumen. * **Option D:** Thionamides like **Propylthiouracil (PTU)** and Methimazole specifically inhibit the Thyroid Peroxidase enzyme, thereby blocking the oxidation of iodide and the subsequent coupling reactions. **High-Yield Clinical Pearls for NEET-PG:** * **Wolff-Chaikoff Effect:** Transient inhibition of thyroid hormone synthesis due to high levels of circulating iodide. * **Pendred Syndrome:** Characterized by sensorineural hearing loss and goiter due to a defect in the Pendrin transporter. * **Most Common Cause:** Globally, iodine deficiency is the most common cause of hypothyroidism; in iodine-sufficient areas, it is Hashimoto’s thyroiditis. * **Screening:** Neonatal screening for hypothyroidism (measuring TSH) is vital as early intervention prevents irreversible mental retardation.
Question 17: 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?
- A. There is no risk of having an affected child in subsequent pregnancies.
- B. The risk of having an affected child is doubled.
- C. There is a one in four chance of having a child with the same disability. (Correct Answer)
- D. This pregnancy is unaffected, but future pregnancies carry a high risk.
Explanation: ### Explanation **1. Why the Correct Answer is Right:** The clinical presentation (ambiguous genitalia in a female sibling and death due to a "metabolic problem," likely an adrenal crisis) is classic for **Congenital Adrenal Hyperplasia (CAH)**, most commonly due to **21-hydroxylase deficiency**. CAH is an **Autosomal Recessive (AR)** disorder. In AR inheritance, if both parents are carriers (which is assumed here as they have already produced one affected child), every subsequent pregnancy carries a: * **25% (1 in 4)** chance of being affected. * **50% (2 in 4)** chance of being an asymptomatic carrier. * **25% (1 in 4)** chance of being unaffected and a non-carrier. **2. Why the Incorrect Options are Wrong:** * **Option A:** Incorrect because AR conditions have a high recurrence risk (25%) in every pregnancy involving the same couple. * **Option B:** The risk is constant (25%) for each pregnancy; it does not "double" based on previous outcomes. * **Option D:** Each pregnancy is an independent event. There is no biological basis for this pregnancy being "safe" while others are high-risk. **3. Clinical Pearls for NEET-PG:** * **Most Common Cause of CAH:** 21-hydroxylase deficiency (90-95%). * **Biochemical Marker:** Elevated **17-hydroxyprogesterone (17-OHP)**. * **Clinical Features:** Virilization in females (ambiguous genitalia) and salt-wasting crisis (hyponatremia, hyperkalemia, hypotension) usually occurring in the 2nd week of life. * **Prenatal Management:** If a fetus is at risk, maternal **Dexamethasone** can be started early (before 9 weeks) to prevent virilization of a female fetus, though this remains a specialized intervention.
Question 18: Precocious puberty is defined as all of the following except?
- A. Onset of menstruation before age of 10 years.
- B. Appearance of breast budding before age of 8 years in females.
- C. Menstruation before age of 8 years. (Correct Answer)
- D. Puberty occurring before 9 years in males.
Explanation: **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.
Question 19: Delayed eruption of teeth is seen in which of the following conditions?
- A. Hypovitaminosis
- B. Hypothyroidism
- C. Hypoparathyroidism
- D. All of the above (Correct Answer)
Explanation: **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.
Question 20: Sweat chloride levels are increased in all of the following conditions except?
- A. Cystic fibrosis
- B. G-6-PD deficiency
- C. Hereditary nephrogenic diabetes insipidus
- D. Obesity (Correct Answer)
Explanation: **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
Practice by Chapter
Disorders of Growth
Practice Questions
Thyroid Disorders
Practice Questions
Disorders of Puberty
Practice Questions
Adrenal Disorders
Practice Questions
Diabetes Mellitus in Children
Practice Questions
Disorders of Calcium and Phosphate Metabolism
Practice Questions
Disorders of Sexual Development
Practice Questions
Hypoglycemia
Practice Questions
Obesity and Metabolic Syndrome
Practice Questions
Pituitary Disorders
Practice Questions
Multiple Endocrine Neoplasia Syndromes
Practice Questions
Endocrine Emergencies
Practice Questions
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