Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 81: All of the following syndromes are associated with short stature EXCEPT?

A. Seckel syndrome
B. Turner syndrome
C. Down syndrome
D. Klinefelter syndrome (Correct Answer)

Explanation: **Explanation:** The core concept in this question is differentiating between chromosomal and genetic syndromes that cause growth failure versus those that cause tall stature. **Why Klinefelter Syndrome (47, XXY) is the correct answer:** Unlike most chromosomal abnormalities, Klinefelter syndrome is classically associated with **tall stature**. This is due to the presence of an extra X chromosome, which carries the **SHOX gene** (Short Stature Homeobox gene). Triple dosage of the SHOX gene leads to increased longitudinal bone growth. Clinically, these patients present with long limbs (increased lower segment), small firm testes, gynecomastia, and infertility. **Why the other options are incorrect:** * **Turner Syndrome (45, X):** This is the classic "textbook" cause of short stature in females. The loss of one SHOX gene (haploinsufficiency) leads to significant growth retardation, along with webbed neck and streak ovaries. * **Seckel Syndrome:** Also known as "bird-headed dwarfism," this is an autosomal recessive disorder characterized by **primordial short stature** (severe intrauterine and postnatal growth restriction) and microcephaly. * **Down Syndrome (Trisomy 21):** Children with Down syndrome consistently plot below the 3rd percentile on standard growth charts. Their short stature is multifactorial, involving skeletal dysplasia and associated endocrine issues like hypothyroidism. **High-Yield Clinical Pearls for NEET-PG:** * **SHOX Gene:** 1 copy = Turner (Short); 2 copies = Normal; 3 copies = Klinefelter/Triple X (Tall). * **Tall Stature Syndromes:** Klinefelter, Marfan syndrome, Homocystinuria, and Sotos syndrome (Cerebral gigantism). * **Short Stature Syndromes:** Turner, Noonan (often called "Male Turner"), Prader-Willi, and Silver-Russell syndrome. * **Bone Age:** In Klinefelter, bone age is usually delayed, whereas in many primordial dwarfisms (like Seckel), it may be normal for height.

Question 82: Hypothyroidism in infancy is characterized by which of the following findings, EXCEPT?

A. Constipation
B. Coarse facies
C. Wide open cranial sutures
D. Hyperthermia (Correct Answer)

Explanation: **Explanation:** Congenital hypothyroidism (CH) results in a generalized slowing of metabolic processes and delayed physical development. **Why Hyperthermia is the correct answer:** Hypothyroidism leads to a **decreased basal metabolic rate (BMR)** and reduced thermogenesis. Consequently, infants with hypothyroidism typically present with **hypothermia** and cold intolerance, not hyperthermia. Hyperthermia is more characteristic of hyperthyroidism (thyroid storm). **Analysis of incorrect options:** * **Constipation:** Thyroid hormones are essential for normal gut motility. Deficiency leads to decreased peristalsis, making constipation one of the earliest and most common signs. * **Coarse Facies:** Due to the accumulation of glycosaminoglycans (myxedema) in the subcutaneous tissues, infants develop a puffy face, macroglossia (large tongue), and a flattened nasal bridge. * **Wide open cranial sutures:** Thyroid hormone is critical for bone maturation. Deficiency causes delayed ossification, resulting in large anterior and posterior fontanelles and wide cranial sutures. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause:** Thyroid dysgenesis (Ectopy is the most frequent specific type). * **Earliest Sign:** Prolonged physiological jaundice (due to delayed glucuronyl transferase activity). * **Other Key Features:** Hoarse cry, umbilical hernia, hypotonia ("floppy baby"), and developmental delay. * **Diagnosis:** Newborn screening (increased TSH, decreased T4). * **Radiology:** Absence of the distal femoral epiphysis at birth is a strong indicator of in-utero hypothyroidism.

Question 83: Which of the following is true in cretinism?

A. Prolonged physiological jaundice present
B. Common in iodine deficiency endemic areas
C. Delayed skeletal development
D. All of these (Correct Answer)

Explanation: **Explanation:** Cretinism, or **Congenital Hypothyroidism**, is a condition of severe thyroid hormone deficiency present at birth. Thyroid hormones ($T_3$ and $T_4$) are critical for metabolic processes, skeletal growth, and neurodevelopment. * **Option A (Prolonged physiological jaundice):** Thyroid hormones are essential for the maturation of the hepatic enzyme **UDP-glucuronyltransferase**. Deficiency leads to delayed conjugation of bilirubin, resulting in indirect hyperbilirubinemia that persists beyond the typical 10–14 days. * **Option B (Common in iodine deficiency):** While "sporadic cretinism" is usually due to thyroid dysgenesis, **"endemic cretinism"** occurs in geographical areas with severe iodine deficiency. It remains the most common cause of preventable intellectual disability worldwide. * **Option C (Delayed skeletal development):** Thyroid hormones stimulate osteoblast activity and epiphyseal maturation. Deficiency leads to delayed bone age, retarded linear growth (short stature), and characteristic **epiphyseal dysgenesis** (stippled epiphysis). Since all three clinical features are hallmark signs of the condition, **Option D** is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** * **Earliest Sign:** Prolonged jaundice or feeding difficulties. * **Classic Triad:** Coarse facies, protuberant tongue (macroglossia), and umbilical hernia. * **Diagnosis:** Newborn screening (best done at 48–72 hours) showing **High TSH** and **Low $T_4$**. * **Radiology:** Absence of the **distal femoral epiphysis** at birth (normally appears at 36 weeks gestation) is a strong indicator of prenatal hypothyroidism. * **Treatment:** Levothyroxine (10–15 μg/kg/day). Treatment must start within 2 weeks of birth to prevent permanent intellectual disability.

Question 84: McCune-Albright syndrome is characterized by which of the following findings?

A. Delayed puberty
B. Hypoparathyroidism
C. Neurofibromas
D. Cafe-au-lait macules (Correct Answer)

Explanation: **Explanation:** **McCune-Albright Syndrome (MAS)** is a rare genetic disorder caused by a post-zygotic somatic mutation in the **GNAS gene**. This mutation leads to constitutive activation of the **Gs-alpha protein**, resulting in the overproduction of cAMP and subsequent overactivity of various endocrine glands. **Why Option D is Correct:** The classic clinical triad of MAS includes: 1. **Polyostotic Fibrous Dysplasia:** Bone is replaced by fibrous tissue, leading to fractures and deformities (e.g., "Shepherd’s crook" deformity). 2. **Cafe-au-lait Macules:** These are typically large, unilateral, and have irregular borders described as the **"Coast of Maine"** appearance (unlike the smooth "Coast of California" borders seen in Neurofibromatosis). 3. **Peripheral Precocious Puberty:** Most common in girls, presenting as recurrent follicular cysts and vaginal bleeding. **Why Other Options are Incorrect:** * **A. Delayed Puberty:** MAS causes **Precocious Puberty** (early onset) due to autonomous ovarian or testicular function, not delayed puberty. * **B. Hypoparathyroidism:** The GNAS mutation in MAS causes *hyperfunction*. While GNAS mutations are linked to pseudohypoparathyroidism, MAS itself is associated with hyper-functioning endocrinopathies like hyperthyroidism or GH excess. * **C. Neurofibromas:** These are hallmark features of **Neurofibromatosis Type 1 (NF1)**. While NF1 also features cafe-au-lait spots, it does not involve fibrous dysplasia or the specific endocrine abnormalities of MAS. **High-Yield Clinical Pearls for NEET-PG:** * **Inheritance:** It is **not inherited**; it occurs due to a spontaneous somatic mutation (mosaicism). * **Radiology:** Fibrous dysplasia shows a characteristic **"Ground-glass appearance"** on X-ray. * **Endocrine involvement:** Can also include GH-secreting pituitary adenomas (Acromegaly) and Cushing syndrome (adrenal hyperplasia).

Question 85: A baby girl with ambiguous genitalia is found to have 21-hydroxylase deficiency of the salt-wasting type. Which of the following karyotypes would you expect to find?

A. 46, XX (Correct Answer)
B. 46, XY
C. 47, XXY
D. 47, XYY

Explanation: **Explanation:** The correct answer is **46, XX**. This case describes **Congenital Adrenal Hyperplasia (CAH)**, specifically the most common form: **21-hydroxylase deficiency**. **Why 46, XX is correct:** In 21-hydroxylase deficiency, there is a block in the conversion of progesterone to deoxycorticosterone and 17-OH progesterone to 11-deoxycortisol. This leads to a deficiency in cortisol and aldosterone (causing salt-wasting) and a shunting of precursors toward the **androgen pathway**. In a genetic female (**46, XX**), the resulting high levels of adrenal androgens during fetal development cause virilization of the external genitalia (clitoromegaly, labial fusion), leading to **ambiguous genitalia**. However, since the internal female organs (uterus, ovaries) are dependent on the absence of Anti-Müllerian Hormone (AMH) and not on adrenal hormones, they develop normally. **Why the other options are incorrect:** * **46, XY:** A male with 21-hydroxylase deficiency will have normal male external genitalia (though they may show signs of precocious puberty later). They do not present with ambiguous genitalia at birth. * **47, XXY (Klinefelter Syndrome):** This presents as a phenotypically male individual, usually diagnosed after puberty due to infertility or gynecomastia, not with neonatal ambiguous genitalia or salt-wasting. * **47, XYY:** This is associated with tall stature and sometimes behavioral issues, but the phenotype is male with normal genitalia. **Clinical Pearls for NEET-PG:** * **Most common cause** of ambiguous genitalia in a newborn is CAH (21-hydroxylase deficiency). * **Biochemical Marker:** Elevated **17-hydroxyprogesterone (17-OHP)** is the diagnostic hallmark. * **Salt-wasting crisis:** Presents at 1–3 weeks of life with hyponatremia, hyperkalemia, and metabolic acidosis. * **Management:** Life-long glucocorticoid (hydrocortisone) and mineralocorticoid (fludrocortisone) replacement.

Question 86: All of the following are true about rickets except?

A. Craniotabes
B. Rachitic rosary
C. Knock-knees
D. Hypotonia (Correct Answer)

Explanation: **Explanation:** The question asks for the "except" statement regarding Rickets. While **Hypotonia** can occur in severe cases of Vitamin D deficiency rickets due to the role of calcium in muscle contraction, it is **not a pathognomonic or specific skeletal sign** of rickets compared to the classic bony deformities listed. In the context of standard NEET-PG questions, the focus is on identifying the characteristic skeletal manifestations versus non-specific systemic signs. **Analysis of Options:** * **Craniotabes (Option A):** This is the earliest skeletal sign of rickets, typically seen in infants <6 months. It refers to the softening of the skull bones (ping-pong ball sensation) over the occiput or parietal bones. * **Rachitic Rosary (Option B):** A classic sign caused by the expansion of the osteochondral junctions of the ribs. These palpable "beads" are prominent in the mid-chest. * **Knock-knees (Genu Valgum) (Option C):** As the child begins to bear weight, the softened long bones deform. While **Genu Varum (bow-legs)** is more common in toddlers, **Genu Valgum (knock-knees)** is a frequent presentation in older children with rickets. * **Hypotonia (Option D):** While muscle weakness and "pot-belly" (due to abdominal wall hypotonia) are associated with rickets, it is considered a secondary or non-skeletal feature. In many standardized exams, if a question asks for "features of rickets," the focus is on the diagnostic bony changes. **High-Yield Clinical Pearls for NEET-PG:** 1. **Earliest Sign:** Craniotabes. 2. **Earliest Radiological Sign:** Widening of the growth plate; followed by **Cupping, Splaying, and Fraying** of the metaphysis (best seen at the lower end of the radius/ulna). 3. **Biochemical Profile:** Low/Normal Calcium, **Low Phosphate**, and **High Alkaline Phosphatase (ALP)**. High ALP is the most sensitive marker for disease activity. 4. **Harrison’s Sulcus:** A horizontal groove along the lower border of the thorax corresponding to the insertion of the diaphragm.

Question 87: All are true about Hypothyroidism except?

A. Delayed dentition
B. Widened fontanelle
C. Distended abdomen
D. Short fontanelle (Correct Answer)

Explanation: **Explanation:** Congenital hypothyroidism (CH) is a common cause of preventable intellectual disability. The clinical manifestations result from a generalized slowing of metabolic processes and delayed skeletal maturation. **Why "Short fontanelle" is the correct answer (the false statement):** In hypothyroidism, there is a significant **delay in bone mineralization and ossification**. This leads to large, **widened fontanelles** (both anterior and posterior) and a wide sagittal suture. A "short" or small fontanelle is not a feature of hypothyroidism; rather, a posterior fontanelle larger than 0.5 cm in a newborn is a classic early diagnostic clue for CH. **Analysis of incorrect options (True statements):** * **A. Delayed dentition:** Thyroid hormones are essential for dental development. Deficiency leads to delayed eruption of deciduous and permanent teeth, as well as enamel hypoplasia. * **B. Widened fontanelle:** As explained above, delayed ossification of the skull bones results in abnormally large fontanelles. * **C. Distended abdomen:** Hypothyroidism causes decreased gastrointestinal motility, leading to constipation and gas accumulation. This, combined with hypotonia (weak abdominal muscles) and an umbilical hernia, results in a protuberant or distended abdomen. **NEET-PG High-Yield Pearls:** * **Most common cause:** Thyroid dysgenesis (Ectopy is the most common specific type). * **Early signs:** Prolonged physiological jaundice, poor feeding, lethargy, and a large posterior fontanelle. * **Late signs:** Hoarse cry, macroglossia (large tongue), umbilical hernia, and "cretinoid" facies. * **Radiology:** Absence of the **distal femoral epiphysis** (normally present at birth) is a hallmark of prenatal thyroid deficiency. * **Screening:** Best done at 48–72 hours of life to avoid the neonatal TSH surge.

Question 88: A child from Southeast Asia presents with severe developmental delay. Physical examination reveals a pot-bellied appearance, pallor, a puffy face, and an enlarged tongue. Which of the following dietary deficiencies is most likely to cause this presentation?

A. Calcium
B. Iodine (Correct Answer)
C. Iron
D. Magnesium

Explanation: ### Explanation The clinical presentation described—severe developmental delay, pot-bellied appearance, puffy face (myxedema), and macroglossia (enlarged tongue)—is a classic description of **Congenital Hypothyroidism** (formerly known as Cretinism). **1. Why Iodine is Correct:** Iodine is an essential trace element required for the synthesis of thyroid hormones ($T_3$ and $T_4$). In regions like Southeast Asia, where soil and water are often iodine-deficient, maternal iodine deficiency leads to fetal iodine deficiency. This results in primary hypothyroidism in the newborn. Thyroid hormones are critical for brain development and linear bone growth during early life; their absence leads to irreversible intellectual disability and the characteristic physical features mentioned. **2. Why the Other Options are Incorrect:** * **Calcium:** Deficiency typically presents as rickets (bony deformities) or tetany/seizures due to hypocalcemia, not developmental delay or macroglossia. * **Iron:** While iron deficiency causes **pallor** (anemia), it does not cause the structural changes like a puffy face or an enlarged tongue. * **Magnesium:** Deficiency usually manifests as neuromuscular irritability, tremors, or seizures, often in association with hypocalcemia. **3. NEET-PG High-Yield Pearls:** * **Most common cause worldwide:** Iodine deficiency (Endemic Cretinism). * **Most common cause in developed nations:** Thyroid dysgenesis (Ectopic thyroid is the most common subtype). * **Early signs:** Prolonged physiological jaundice, hoarse cry, and umbilical hernia. * **Screening:** Best done via **heel-prick test** for TSH levels between 48–72 hours of birth. * **Treatment:** Levothyroxine; if started within the first 2 weeks of life, the prognosis for neurodevelopment is excellent.

Question 89: Short stature secondary to growth hormone deficiency is associated with all of the following EXCEPT?

A. Normal body proportion
B. Normal bone age (Correct Answer)
C. Delayed dentition
D. Delayed puberty

Explanation: **Explanation** Growth Hormone Deficiency (GHD) is a classic cause of **proportionate short stature** resulting from the inadequate production of growth hormone from the anterior pituitary. **Why "Normal bone age" is the correct answer:** In GHD, there is a significant delay in skeletal maturation. Growth hormone is essential for the progression of the epiphyseal plates; therefore, its absence leads to a **delayed bone age** (Bone Age < Chronological Age). A "normal bone age" in a child with short stature usually points toward **Constitutional Delay of Growth and Puberty (CDGP)** or **Genetic/Familial Short Stature**, rather than an endocrine deficiency. **Analysis of other options:** * **Normal body proportion:** Unlike skeletal dysplasias (e.g., Achondroplasia) or Hypothyroidism, GHD causes proportionate growth failure. The upper segment to lower segment (US:LS) ratio remains appropriate for the child's age. * **Delayed dentition:** Growth hormone influences the development and eruption of teeth. Children with GHD typically show a significant delay in the eruption of both deciduous and permanent teeth. * **Delayed puberty:** GH acts synergistically with gonadotropins. Deficiency often results in delayed onset of puberty and underdeveloped secondary sexual characteristics. **NEET-PG High-Yield Pearls:** * **Clinical Triad of GHD:** "Cherubic" appearance (doll-like facies), truncal obesity (increased subcutaneous fat), and a high-pitched voice. * **Screening Test:** Insulin-like Growth Factor 1 (IGF-1) and IGFBP-3 levels. * **Gold Standard Diagnosis:** GH Stimulation Test (using Insulin, Arginine, or Clonidine). A peak GH level **<10 ng/mL** is diagnostic. * **Micropenis:** In neonates, GHD may present with hypoglycemia and a micropenis (due to lack of synergistic effect with LH/FSH).

Question 90: A 6-month-old boy weighing 3.2 kg presents with recurrent vomiting and polyuria. Investigations show blood urea 60 mg/dL, creatinine 0.7 mg/dL, calcium 12.8 mg/dL, phosphate 3 mg/dL, pH 7.45, bicarbonate 25 mEq/L, and PTH 140 pg/mL. What is the most likely diagnosis?

A. Bartter syndrome
B. Mutation of the calcium-sensing receptor (Correct Answer)
C. Pseudopseudohypoparathyroidism
D. Parathyroid adenoma

Explanation: **Explanation:** The clinical presentation of hypercalcemia (12.8 mg/dL), failure to thrive (weight 3.2 kg at 6 months), and polyuria in an infant, combined with an inappropriately elevated PTH (140 pg/mL), points toward **Neonatal Severe Hyperparathyroidism (NSHPT)**. This condition is caused by a homozygous inactivating **mutation of the calcium-sensing receptor (CaSR)**. In a normal state, high calcium levels suppress PTH secretion via the CaSR. When these receptors are defective, the "set-point" for calcium sensing is shifted upward; the parathyroid glands do not "see" the high calcium and continue to secrete PTH. This leads to severe hypercalcemia, bone demineralization, and renal salt/water loss. **Why other options are incorrect:** * **Bartter Syndrome:** Presents with hypokalemia, metabolic alkalosis, and polyuria, but calcium levels are typically normal (though hypercalciuria is present). * **Pseudopseudohypoparathyroidism:** Characterized by Albright Hereditary Osteodystrophy (AHO) phenotype but with **normal** calcium, phosphate, and PTH levels. * **Parathyroid Adenoma:** Extremely rare in infants. While it causes hypercalcemia and high PTH, the neonatal onset and severity in this age group strongly favor a genetic CaSR mutation. **High-Yield Clinical Pearls for NEET-PG:** * **Familial Hypocalciuric Hypercalcemia (FHH):** The heterozygous form of CaSR mutation; usually asymptomatic with low urinary calcium excretion. * **NSHPT:** The homozygous form; life-threatening hypercalcemia in neonates. * **Key Lab Triad for CaSR mutations:** Hypercalcemia + Inappropriately high/normal PTH + Low urinary calcium (fractional excretion of calcium <0.01).

Practice by Chapter

Disorders of Growth

Practice Questions

Thyroid Disorders

Practice Questions

Disorders of Puberty

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Adrenal Disorders

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Diabetes Mellitus in Children

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Disorders of Calcium and Phosphate Metabolism

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Disorders of Sexual Development

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Hypoglycemia

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Obesity and Metabolic Syndrome

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Pituitary Disorders

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Multiple Endocrine Neoplasia Syndromes

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Endocrine Emergencies

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