Endocrinology Practice Questions

Q: Laron syndrome is due to which of the following?

Growth hormone insensitivity. **Explanation:** **Laron Syndrome** (also known as Laron-type dwarfism) is an autosomal recessive disorder characterized by a mutation in the **Growth Hormone Receptor (GHR) gene**. This results in **Growth Hormone (GH) insensitivity**, meaning that while the pituitary gland produces GH, the peripheral tissues (especially the liver) cannot respond to it. Consequently, there is a failure to produce **Insulin-like Growth Factor-1 (IGF-1)**, which is essential for linear growth. * **Why Option A is correct:** The primary defect is at the receptor level. Patients present with clinical features of GH deficiency but have **elevated or normal serum GH levels** and **very low IGF-1 levels**. * **Why Option B is incorrect:** GH deficiency (Hypopituitarism) involves a lack of hormone production. In Laron syndrome, GH is present but ineffective. * **Why Option C is incorrect:** "Paradoxical GH deficiency" is not a standard clinical term for this pathology. * **Why Option D is incorrect:** Cushing syndrome causes growth failure due to hypercortisolism, which inhibits the growth plate directly and interferes with GH secretion, but it is not the mechanism for Laron syndrome. **High-Yield Clinical Pearls for NEET-PG:** * **Phenotype:** Severe short stature, "doll-like" facies (prominent forehead, depressed nasal bridge), small hands/feet, and truncal obesity. * **Biochemical Hallmark:** ↑ GH + ↓ IGF-1. * **Treatment:** Recombinant human **IGF-1 (Mecasermin)**. Exogenous GH is ineffective because the receptors are non-functional. * **Unique Fact:** Patients with Laron syndrome have a notably **reduced risk of developing cancer and Type 2 diabetes.**

Q: The diagnostic triad of exophthalmos, diabetes insipidus, and bone lesions is characteristic of which condition?

Hand-Schüller-Christian disease. ### Explanation **Hand-Schüller-Christian disease** is a chronic disseminated form of **Langerhans Cell Histiocytosis (LCH)**. It typically presents in children and is classically defined by the **Christian Triad**: 1. **Bone Lesions:** Specifically "punched-out" lytic lesions in the skull. 2. **Exophthalmos:** Caused by histiocytic infiltration of the retro-orbital space. 3. **Diabetes Insipidus:** Resulting from infiltration of the posterior pituitary or hypothalamus (leading to polyuria and polydipsia). #### Analysis of Incorrect Options: * **B. Letterer-Siwe disease:** This is the acute disseminated form of LCH, occurring usually in infants (<2 years). It presents with a seborrheic-like skin rash, hepatosplenomegaly, and lymphadenopathy. It is more aggressive and lacks the specific triad mentioned. * **C. Fibrous dysplasia:** A skeletal disorder where normal bone is replaced by fibrous tissue. While it can cause bone lesions and facial asymmetry (Leontiasis ossea), it does not cause diabetes insipidus. * **D. Osteoporosis:** A metabolic bone disease characterized by low bone mineral density and increased fracture risk; it has no association with exophthalmos or diabetes insipidus. #### High-Yield Clinical Pearls for NEET-PG: * **LCH Pathology:** Characterized by the proliferation of Langerhans cells which are **CD1a+**, **S100+**, and **CD207 (Langerin)+**. * **Electron Microscopy:** Look for **Birbeck granules** (tennis-racket shaped cytoplasmic inclusions). * **Radiology:** Skull X-rays show "punched-out" lytic lesions without a sclerotic rim. * **Eosinophilic Granuloma:** The mildest, localized form of LCH, usually involving a single bone.

Q: Which of the following is true in cretinism?

Prolonged physiological jaundice present. **Explanation:** Congenital hypothyroidism (Cretinism) is one of the most common preventable causes of intellectual disability. The clinical presentation is often subtle at birth due to the transplacental passage of maternal thyroid hormones. **Why Option C is Correct:** Prolonged physiological jaundice (unconjugated hyperbilirubinemia) is one of the earliest clinical signs of cretinism. Thyroid hormones are essential for the maturation of the enzyme **hepatic glucuronosyltransferase**. Deficiency leads to delayed conjugation of bilirubin, causing jaundice to persist beyond the typical 10–14 day window. **Analysis of Incorrect Options:** * **Option A:** Goiter is **not** a universal finding. While it can occur in dyshormonogenesis or maternal antithyroid drug use, the most common cause of sporadic cretinism is **thyroid dysgenesis** (aplasia, hypoplasia, or ectopy), where the thyroid gland is absent or small, meaning no goiter is present. * **Option B:** While T4 levels are low, the **gold standard screening test** and the most sensitive indicator for primary hypothyroidism is an **elevated serum TSH**. Relying solely on T4 can miss cases of mild or compensated hypothyroidism. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause:** Thyroid Dysgenesis (80-85%). * **Early Signs:** Poor feeding, lethargy, macroglossia, large posterior fontanelle (>0.5 cm), and umbilical hernia. * **Radiological Sign:** Absence of the **distal femoral epiphysis** (normally present at birth) indicates prenatal hypothyroidism. * **Treatment:** Levothyroxine (10-15 μg/kg/day) should be started immediately to prevent irreversible neurodevelopmental delay.

Q: Which of the following may be a presenting feature of phenylketonuria?

Salaam spasms. **Explanation:** **Phenylketonuria (PKU)** is an autosomal recessive inborn error of metabolism caused by a deficiency of the enzyme **phenylalanine hydroxylase (PAH)**. This leads to the accumulation of phenylalanine and its metabolites (like phenylpyruvic acid) in the blood and brain. **Why Option A is Correct:** Untreated PKU leads to severe intellectual disability and neurological manifestations. **Salaam spasms** (also known as infantile spasms or West Syndrome) are a classic neurological presentation in infants with PKU. The accumulation of phenylalanine interferes with neurotransmitter synthesis (dopamine and serotonin) and myelination, leading to hypsarrhythmia on EEG and clinical spasms. **Analysis of Incorrect Options:** * **B. Huntington’s chorea:** This is an autosomal dominant neurodegenerative disorder characterized by CAG repeats. It is unrelated to phenylalanine metabolism. * **C. Diarrhoea:** While some metabolic disorders present with GI distress, PKU is not typically associated with diarrhea. * **D. Haematemesis:** This refers to vomiting blood, usually seen in portal hypertension or peptic ulcer disease, and is not a feature of PKU. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Triad:** Intellectual disability, seizures (Salaam spasms), and hypopigmentation (fair skin/blue eyes due to decreased melanin). * **Odour:** Patients often have a characteristic **"mousy" or "musty" odor** in urine and sweat. * **Diagnosis:** Guthrie test (bacterial inhibition assay) or tandem mass spectrometry for screening. * **Management:** Lifelong restriction of dietary phenylalanine (maintain levels between 2–6 mg/dL). * **Maternal PKU:** If a mother has high phenylalanine levels during pregnancy, the fetus may develop microcephaly, CHD, and growth restriction (teratogenic effect).

Q: A 5-year-old boy with IDDM (Insulin-Dependent Diabetes Mellitus) on a single morning dose of insulin has begun to have nightly enuresis. His fasting blood sugar (FBS) level generally is 200-250 mg/dl, and his blood glucose level before supper generally is 75-150 mg/dl. What is the most likely cause of this patient's enuresis?

Glycosuria from under-insulinization overnight. **Explanation:** The core issue in this clinical scenario is **inadequate insulin coverage** during the night. The patient is on a single morning dose of insulin, which typically peaks in the afternoon and wears off by the evening/night. 1. **Why Option A is correct:** The high Fasting Blood Sugar (FBS) of 200–250 mg/dl indicates that the insulin effect has dissipated overnight. When blood glucose exceeds the **renal threshold (approx. 180 mg/dl)**, glucose is excreted in the urine (glycosuria). Glucose acts as an osmotic diuretic, leading to **polyuria**. In a child, this increased urine volume during sleep manifests as secondary nocturnal enuresis. 2. **Why other options are incorrect:** * **Option B:** While chronic disease can cause psychological stress, the physiological evidence of hyperglycemia (FBS 200+) strongly points toward a metabolic cause. * **Option C:** UTIs can cause enuresis, but the classic presentation would include dysuria, frequency, or urgency, and it wouldn't explain the high FBS. * **Option D:** The **Somogyi phenomenon** refers to rebound hyperglycemia in the morning following *nocturnal hypoglycemia*. However, this patient's pre-supper glucose (75–150 mg/dl) is relatively normal/low, and a single morning dose is unlikely to cause midnight hypoglycemia followed by such high fasting levels without intermediate coverage. **Clinical Pearls for NEET-PG:** * **Renal Threshold for Glucose:** 180 mg/dl. * **Dawn Phenomenon:** Early morning hyperglycemia due to a physiological surge in growth hormone and cortisol (requires *increasing* nighttime insulin). * **Somogyi Effect:** Post-hypoglycemic hyperglycemia (requires *decreasing* nighttime insulin). * **Management:** For this patient, the best step is moving to a **split-mixed regimen** (morning and evening doses) or a basal-bolus regimen to ensure 24-hour coverage.

Q: In Pheochromocytoma, which of the following is increased in urine?

VMA. **Explanation:** **Pheochromocytoma** is a catecholamine-secreting tumor arising from the chromaffin cells of the adrenal medulla (or extra-adrenal sympathetic ganglia). The pathophysiology involves the overproduction of epinephrine and norepinephrine. **Why VMA is the correct answer:** Catecholamines are metabolized via two primary pathways involving the enzymes **COMT** (Catechol-O-methyltransferase) and **MAO** (Monoamine oxidase). * Norepinephrine and Epinephrine are first converted into **Metanephrines** (Metanephrine and Normetanephrine). * These are further broken down into **Vanillylmandellic Acid (VMA)**, which is the final stable end-product excreted in the urine. * *Note:* While 24-hour urinary VMA is a classic marker, **urinary/plasma metanephrines** are now considered more sensitive for screening. **Why other options are incorrect:** * **B. Aldosterone:** Secreted by the *Zona Glomerulosa* of the adrenal cortex. It is increased in Conn’s Syndrome, not Pheochromocytoma. * **C. Cortisol:** Secreted by the *Zona Fasciculata* of the adrenal cortex. It is the hallmark of Cushing’s Syndrome. * **D. 17-Hydroxyprogesterone:** A precursor in the cortisol synthesis pathway. It is the primary screening marker for **Congenital Adrenal Hyperplasia (CAH)** due to 21-hydroxylase deficiency. **High-Yield Clinical Pearls for NEET-PG:** * **Rule of 10s:** 10% are bilateral, 10% are malignant, 10% are extra-adrenal (Paragangliomas), and 10% occur in children. * **Clinical Triad:** Episodic headache, sweating (diaphoresis), and tachycardia/palpitations. * **Associated Syndromes:** MEN 2A and 2B, von Hippel-Lindau (VHL), and Neurofibromatosis type 1 (NF1). * **Surgical Management:** Always give **Alpha-blockers** (e.g., Phenoxybenzamine) *before* Beta-blockers to prevent a hypertensive crisis.

Q: What is the most common cause of congenital adrenal hyperplasia?

21-Hydroxylase deficiency. **Explanation:** Congenital Adrenal Hyperplasia (CAH) is a group of autosomal recessive disorders caused by a deficiency of enzymes required for cortisol synthesis. **Why 21-Hydroxylase deficiency is correct:** Deficiency of **21-Hydroxylase** is the most common cause, accounting for **>90-95% of all CAH cases**. This enzyme is responsible for converting progesterone to 11-deoxycorticosterone and 17-hydroxyprogesterone to 11-deoxycortisol. Its absence leads to decreased cortisol and aldosterone, with a compensatory increase in ACTH. This "shunts" precursors toward the androgen pathway, leading to virilization. **Why the other options are incorrect:** * **11-beta-Hydroxylase deficiency:** The second most common cause (~5-8%). It presents with virilization but is uniquely characterized by **hypertension** due to the accumulation of 11-deoxycorticosterone (a mineralocorticoid). * **17-alpha-Hydroxylase deficiency:** Rare. It leads to a decrease in both cortisol and sex hormones, resulting in **delayed puberty/sexual infantilism** and hypertension (due to excess mineralocorticoids). * **3-beta-Hydroxysteroid dehydrogenase deficiency:** Very rare. It affects all three pathways (mineralocorticoids, glucocorticoids, and sex steroids), often leading to ambiguous genitalia in both males and females. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Presentation:** Salt-wasting (hypotension, hyponatremia, hyperkalemia) and ambiguous genitalia in females. * **Diagnostic Marker:** Elevated **17-hydroxyprogesterone (17-OHP)** levels. * **Treatment:** Glucocorticoid (Hydrocortisone) and Mineralocorticoid (Fludrocortisone) replacement. * **Rule of Thumb:** If the enzyme starts with **'1'** (11, 17), it causes **Hypertension**. If it ends with **'1'** (21, 11), it causes **Virilization**.

Question 1

Laron syndrome is due to which of the following?

Accepted Answer

Growth hormone insensitivity

Answer

Growth hormone deficiency

Answer

Paradoxical growth hormone deficiency

Answer

Growth failure due to Cushing syndrome

Question 2

An 18-month-old child with ambiguous genitalia presented to the hospital. His BP is 118/78 mm Hg, serum K+ is 6 mEq/L, and serum sodium is 120 mEq/L. The patient was started on I.V. fluids. What additional specific therapy will you add?

Accepted Answer

Hydrocortisone

Answer

Potassium binding resin

Answer

Digoxin

Answer

Calcium gluconate

Question 3

The diagnostic triad of exophthalmos, diabetes insipidus, and bone lesions is characteristic of which condition?

Accepted Answer

Hand-Schüller-Christian disease

Answer

Letterer-Siwe disease

Answer

Fibrous dysplasia

Answer

Osteoporosis

Question 4

A child has deficient bone mineralization with low serum calcium, high serum phosphorus, with decreased urinary excretion of calcium and phosphorus, and elevated levels of alkaline phosphatase. What is the most likely diagnosis?

Accepted Answer

Renal glomerular rickets

Answer

Nutritional rickets

Answer

Renal tubular rickets

Answer

Celiac rickets

Question 5

Which of the following is true in cretinism?

Accepted Answer

Prolonged physiological jaundice present

Answer

Goiter present at birth

Answer

Can be diagnosed by serum T4 levels

Answer

All of the above

Question 6

Which of the following may be a presenting feature of phenylketonuria?

Accepted Answer

Salaam spasms

Answer

Huntington's chorea

Answer

Diarrhoea

Answer

Haematemesis

Question 7

A 5-year-old boy with IDDM (Insulin-Dependent Diabetes Mellitus) on a single morning dose of insulin has begun to have nightly enuresis. His fasting blood sugar (FBS) level generally is 200-250 mg/dl, and his blood glucose level before supper generally is 75-150 mg/dl. What is the most likely cause of this patient's enuresis?

Accepted Answer

Glycosuria from under-insulinization overnight

Answer

Stress of chronic disease

Answer

Urinary tract infection

Answer

Somogyi phenomenon

Question 8

In Pheochromocytoma, which of the following is increased in urine?

Accepted Answer

VMA

Answer

Aldosterone

Answer

Cortisol

Answer

17 hydroxyprogesterone

Question 9

Mental retardation is not a feature of which one of the following mucopolysaccharidoses?

Accepted Answer

Morquio syndrome (MPS IV)

Answer

Hurler syndrome (MPS I)

Answer

Hunter syndrome (MPS II)

Answer

Sanfilippo syndrome (MPS III)

Question 10

What is the most common cause of congenital adrenal hyperplasia?

Accepted Answer

21-Hydroxylase deficiency

Answer

11-Hydroxylase deficiency

Answer

17-a-Hydroxylase deficiency

Answer

3-beta-Hydroxysteroid dehydrogenase deficiency

Endocrinology — MCQs

Endocrinology — MCQs

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