Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 1391: A female child presents with hypertension, hyperpigmentation and virilization, she is most likely to be suffering from deficiency of?

A. 3 beta hydroxylase
B. 21 alpha hydroxylase
C. 11 beta hydroxylase deficiency (Correct Answer)
D. 17 alpha hydroxylase

Explanation: ***11 beta hydroxylase deficiency*** - This deficiency leads to an accumulation of **11-deoxycorticosterone (DOC)**, a potent mineralocorticoid that causes **hypertension**. [1] - The excess adrenal androgens (due to shunting of precursors down the androgen pathway) cause **virilization** and **hyperpigmentation** from increased ACTH stimulating melanocortin receptors. [1] *3 beta hydroxylase* - This deficiency causes a severe form of **congenital adrenal hyperplasia (CAH)** with impaired synthesis of all adrenal steroids. [1] - It presents with **salt wasting** and **ambiguous genitalia** in females due to lack of cortisol, aldosterone, and sex steroids. *21 alpha hydroxylase* - The most common form of CAH, resulting in decreased **cortisol** and **aldosterone**, and increased adrenal androgens. - It presents with **salt wasting** or **virilization** (depending on severity), but typically **hypotension** rather than hypertension. *17 alpha hydroxylase* - This deficiency impairs the synthesis of **cortisol** and **androgens**, leading to an accumulation of **mineralocorticoid precursors** like DOC. - Patients present with **hypertension**, **hypokalemia**, and **sexual infantilism** (lack of pubertal development) rather than virilization.

Question 1392: A female is on hormone replacement therapy for her menopausal symptoms. She is worried about her bone strength because her mom and sister had osteoporosis after the age of 50. All are given for prevention of osteoporosis along with hormonal replacement therapy, EXCEPT:

A. Calcium
B. Vitamin-E (Correct Answer)
C. Vit.D
D. None of the options

Explanation: ***Vitamin-E*** - **Vitamin-E** is an **antioxidant** vitamin that primarily protects cells from oxidative damage. - It does not play a direct role in **bone metabolism** or the prevention of osteoporosis. *Calcium* - **Calcium** is a fundamental component of bone tissue and is essential for maintaining **bone density** [1]. - Adequate calcium intake is crucial for **osteoporosis prevention**, especially in postmenopausal women [1], [2]. *Vit.D* - **Vitamin D** is essential for **calcium absorption** in the gut and its incorporation into bones. - Without sufficient Vitamin D, calcium cannot be effectively utilized, leading to compromised **bone health**. *None of the options* - This option is incorrect because Vitamin E does not contribute to osteoporosis prevention, making it the correct answer to the "EXCEPT" question. - Calcium and Vitamin D are both vital for bone strength, so stating that none of the options fit would be inaccurate [1].

Question 1393: Apparent mineralocorticoid excess is due to

A. Sgk gene
B. CYP 11B2
C. CYP11A
D. 11-β hydroxysteroid dehydrogenase (Correct Answer)

Explanation: ***11-β hydroxysteroid dehydrogenase*** - Apparent mineralocorticoid excess (AME) is caused by a deficiency of **11-β-hydroxysteroid dehydrogenase type 2 (11β-HSD2)**, which is responsible for inactivating **cortisol** to **cortisone** [1]. - Without proper inactivation, elevated cortisol levels can then **bind to and activate mineralocorticoid receptors (MR)** in the kidney, leading to symptoms mimicking hyperaldosteronism [1]. *Sgk gene* - The **SGK1 gene** encodes for **serum and glucocorticoid-regulated kinase 1**, which plays a role in renal sodium absorption, but not directly in the cause of AME [1]. - While **SGK1** is involved in epithelial sodium channel (ENaC) regulation, its overactivity is a downstream effect, not the primary cause of AME [1]. *CYP 11B2* - **CYP11B2** (aldosterone synthase) is responsible for the final step in **aldosterone synthesis** [1]. - While it's crucial for mineralocorticoid production, a deficiency in **11β-HSD2** causes **cortisol-induced mineralocorticoid effects**, not issues with aldosterone synthesis itself. *CYP11A* - **CYP11A** (cholesterol side-chain cleavage enzyme) initiates the synthesis of all steroid hormones from **cholesterol** [1]. - Defects in **CYP11A** would lead to a more severe and broad deficiency in steroid production, not specifically apparent mineralocorticoid excess.

Question 1394: Hypocalcemia is characterized by all except

A. Carpopedal spasm
B. Hyperactive tendon reflexes
C. Numbness and tingling of circumoral region
D. Shortening of Q-T interval in ECG (Correct Answer)

Explanation: ***Shortening of Q-T interval in ECG*** - Hypocalcemia typically causes **prolongation of the QT interval** on an ECG due to delayed repolarization of ventricular myocardial cells. - A **shortened QT interval** is usually associated with hypercalcemia or conditions like short QT syndrome. *Carpopedal spasm* - This is a classic sign of hypocalcemia, known as **Trousseau's sign**, elicited by inflating a blood pressure cuff above systolic pressure, which causes spasm of the hand and foot. - It results from increased neuromuscular irritability due to lower calcium levels. *Hyperactive tendon reflexes* - Hypocalcemia leads to **increased neuromuscular excitability**, which manifests as hyperactive or brisk deep tendon reflexes. - This heightened reflex activity is a common neurological symptom of low calcium. *Numbness and tingling of circumoral region* - This symptom, known as **paresthesia**, is a very common and early manifestation of hypocalcemia. - It occurs due to the increased excitability of peripheral nerves caused by reduced extracellular calcium.

Question 1395: A 10 day old male pseudohermaphrodite child with 46 XY karyotype presents with BP of 110/80 mmHg. Most likely enzyme deficiency is:

A. 17 hydroxylase (Correct Answer)
B. 3-beta hydroxylase
C. 11 hydroxylase
D. 21 hydroxylase

Explanation: ***17-hydroxylase*** - Deficiency of **17α-hydroxylase** leads to impaired synthesis of androgens and estrogens, resulting in **male pseudohermaphroditism** (46 XY DSD) [1]. - The block in cortisol and sex steroid synthesis shunts precursors toward mineralocorticoid production (e.g., **corticosterone, deoxycorticosterone**), causing **hypertension** and **hypokalemia** [1]. *3-beta hydroxysteroid dehydrogenase* - This deficiency affects the synthesis of all three classes of adrenal steroids (glucocorticoids, mineralocorticoids, and androgens). - It would typically lead to **salt wasting**, **hypotension**, and severe **masculinization in females** or **pseudohermaphroditism in males**, but without hypertension. *11-hydroxylase* - Deficiency of **11β-hydroxylase** leads to accumulation of **11-deoxycorticosterone** (DOC) and **11-deoxycortisol**, which have mineralocorticoid activity. - This causes **hypertension** and **virilization** (overproduction of weak androgens), but it does not cause male pseudohermaphroditism. *21-hydroxylase* - This is the most common form of **congenital adrenal hyperplasia** (CAH) and results in impaired synthesis of cortisol and aldosterone, leading to an accumulation of androgen precursors. - Clinical features include **virilization in females**, **salt wasting** (due to aldosterone deficiency), and **hypotension** rather than hypertension in the severe forms, and no DSD in males.

Question 1396: Most common endocrine complication of intracranial radiotherapy is

A. TSH deficiency
B. Addison's disease
C. Cushing's syndrome
D. Growth hormone deficiency (Correct Answer)

Explanation: **Growth hormone deficiency** - **Growth hormone (GH)-producing cells** in the pituitary are highly sensitive to radiation, making GH deficiency the earliest and most common endocrine complication after intracranial radiotherapy [1]. - This deficiency can manifest years after radiation and cause growth failure in children and reduced bone mineral density or fatigue in adults. *TSH deficiency* - While **TSH deficiency** (central hypothyroidism) can occur, it typically manifests later than GH deficiency and is less common [1]. - It indicates damage to the **thyrotrophs** of the pituitary, which are generally more resistant to radiation than somatotrophs. *Addison's disease* - **Addison's disease** is primary adrenal insufficiency, where the adrenal glands fail to produce enough cortisol and aldosterone. It is not caused by intracranial radiotherapy [1]. - Intracranial radiotherapy can lead to **central adrenal insufficiency** due to ACTH deficiency, but not primary Addison's. *Cushing's syndrome* - **Cushing's syndrome** is caused by prolonged exposure to high levels of cortisol, often due to an **ACTH-producing pituitary adenoma** (Cushing's disease) or adrenal tumor [2]. It is not a complication of intracranial radiotherapy itself. - Radiotherapy may be used **to treat** Cushing's disease, but it does not cause the condition.

Question 1397: Hypophosphatemia is caused by-

A. Primary hyperthyroidism
B. Primary hypothyroidism
C. Hypoparathyroidism
D. Primary hyperparathyroidism (Correct Answer)

Explanation: ***Primary hyperparathyroidism*** - In **primary hyperparathyroidism**, excessive parathyroid hormone (PTH) leads to increased **renal phosphate excretion** and inhibition of its reabsorption, resulting in hypophosphatemia [1][2]. - PTH's primary role is to raise **serum calcium**, but it indirectly lowers phosphate by acting on the kidneys and bones [3]. *Primary hyperthyroidism* - **Hyperthyroidism** typically causes an increase in **bone turnover**, but does not directly lead to **hypophosphatemia** as a primary feature. - While high thyroid hormone levels can affect calcium and phosphate metabolism, it's more commonly associated with hypercalcemia rather than hypophosphatemia. *Primary hypothyroidism* - **Hypothyroidism** can lead to altered bone metabolism, but it does not directly cause **hypophosphatemia**. - Renal phosphate handling is generally not significantly impaired in a way that would lead to low serum phosphate levels. *Hypoparathyroidism* - **Hypoparathyroidism** is characterized by deficient PTH production, which leads to **decreased renal phosphate excretion**, resulting in **hyperphosphatemia**, not hypophosphatemia [4]. - The lack of PTH also causes hypocalcemia due to reduced bone resorption and impaired renal calcium reabsorption.

Question 1398: Gigantism is most commonly caused by:

A. Chromosomal abnormalities
B. Pituitary adenomas (Correct Answer)
C. Parathyroid disorders
D. Thyroid disorders

Explanation: Pituitary adenomas - Gigantism is characterized by excessive growth and height, primarily caused by hypersecretion of growth hormone (GH) before the fusion of epiphyseal plates [1]. - The most common cause of sustained GH hypersecretion leading to gigantism is a pituitary adenoma, a benign tumor of the pituitary gland's somatotroph cells [2], [3]. Chromosomal abnormalities - While some genetic conditions can cause tall stature (e.g., Klinefelter syndrome), they are not the primary cause of gigantism, which is specifically related to excessive GH production. - Conditions like Marfan syndrome may cause tall stature but do not involve GH excess or pituitary adenomas. Parathyroid disorders - These primarily affect calcium and phosphate metabolism, leading to conditions like hypercalcemia or hypocalcemia. - They do not directly cause excessive growth hormone secretion or gigantism. Thyroid disorders - Hyperthyroidism can cause increased metabolic rate and weight loss, but it does not lead to the massive skeletal overgrowth seen in gigantism. - Hypothyroidism in childhood can cause dwarfism or stunted growth, which is the opposite of gigantism.

Question 1399: Mr. Murali has 126 mg/dl of fasting plasma glucose. His venous plasma glucose 2h after ingestion of 75g oral glucose load is 149 mg/dl. This patient comes under which stage of WHO diagnostic criteria of diabetes & intermediate hyperglycemia?

A. Decreased glucose resistance
B. IFG - Impaired fasting glucose
C. Diagnosis of diabetes (Correct Answer)
D. Impaired glucose tolerance

Explanation: **Diagnosis of diabetes** - The **fasting plasma glucose (FPG)** of 126 mg/dL meets the WHO criterion for **diabetes**, which is FPG ≥ 126 mg/dL [1]. - Although the 2-hour post-glucose load (149 mg/dL) falls within the **impaired glucose tolerance (IGT)** range (140-199 mg/dL), the elevated fasting glucose alone is sufficient for a diabetes diagnosis according to WHO guidelines. *Decreased glucose resistance* - This term is not a standard diagnostic category recognized by the WHO for glucose metabolism disorders. - Glucose resistance is more commonly associated with conditions like **insulin resistance** rather than a specific diagnostic stage [1]. *IFG - Impaired fasting glucose* - **Impaired fasting glucose (IFG)** is defined by a fasting plasma glucose level between 100 mg/dL and 125 mg/dL. - Mr. Murali's fasting glucose of 126 mg/dL is higher than the upper limit for IFG [1]. *Impaired glucose tolerance* - **Impaired glucose tolerance (IGT)** is defined by a 2-hour post-glucose load plasma glucose level between 140 mg/dL and 199 mg/dL. - While Mr. Murali's 2-hour reading of 149 mg/dL falls within this range, the elevated fasting glucose level takes precedence for the overall diagnosis [1].

Question 1400: Short 4th metacarpal is a feature of

A. Achondroplasia
B. Scleroderma
C. Turner syndrome
D. Pseudohypoparathyroidism (Correct Answer)

Explanation: ***Pseudohypoparathyroidism*** - **Short 4th metacarpal** is a classic skeletal feature, often referred to as **Albright's hereditary osteodystrophy**, which is pathognomonic for pseudohypoparathyroidism type 1A [2]. - This condition results from **end-organ resistance to parathyroid hormone (PTH)**, leading to hypocalcemia and hyperphosphatemia despite elevated PTH levels [2]. *Achondroplasia* - Characterized by **short limbs** due to abnormal endochondral ossification, but typically affects all long bones symmetrically and does not specifically cause a short 4th metacarpal as a distinct feature [1]. - While patients have short hands, the **overall hand structure** is disproportionate rather than a specific short metacarpal [1]. *Scleroderma* - This is a **connective tissue disease** characterized by fibrosis of the skin and internal organs; it does not typically cause skeletal abnormalities like a short 4th metacarpal. - Skeletal manifestations usually involve **erosions** and **joint contractures** due to skin tightening, not developmental bone anomalies. *Turner syndrome* - Patients with Turner syndrome often have **short stature** and various skeletal findings, including **short 4th metacarpals** in some cases [3]. - However, pseudohypoparathyroidism is more specifically and consistently associated with the **Albright's hereditary osteodystrophy phenotype**, which includes the short 4th metacarpal.

Practice by Chapter

Diabetes Mellitus

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Thyroid Disorders

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Adrenal Gland Disorders

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Pituitary Disorders

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Calcium and Bone Metabolism

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Reproductive Endocrinology

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Lipid Disorders

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Endocrine Hypertension

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Multiple Endocrine Neoplasia

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Obesity and Metabolic Syndrome

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Neuroendocrine Tumors

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Endocrine Emergencies

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