Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 1671: Among the following, which is a feature of testicular feminization syndrome?

A. XX pattern
B. Commonly reared as male
C. Well formed female internal genitalia
D. High testosterone levels (Correct Answer)

Explanation: High testosterone levels - Individuals with testicular feminization syndrome (also known as androgen insensitivity syndrome) have testes that produce normal to high levels of testosterone. [1] - However, due to a lack of functional androgen receptors, the body cannot respond to this testosterone, leading to feminization. [1] XX pattern - Testicular feminization syndrome is characterized by a 46,XY karyotype, meaning individuals have male chromosomes. - The XX pattern refers to female chromosomal makeup, which is not present in this syndrome. Commonly reared as male - Due to their female external phenotype and development, individuals with testicular feminization syndrome are almost invariably reared as females. - Their condition is often diagnosed when they present with primary amenorrhea or lack of pubertal feminization. Well formed female internal genitalia - Individuals with this syndrome have undescended testes but lack a uterus and fallopian tubes because the testes produce Müllerian Inhibiting Substance (MIS), which causes regression of Müllerian structures. - They typically have a shortened or blind-ended vagina but no other internal female reproductive organs.

Question 1672: Which of the following statements about 21-Hydroxylase deficiency is false?

A. It leads to female pseudohermaphroditism.
B. It is the most common cause of congenital adrenal hyperplasia.
C. It is inherited in an autosomal recessive manner.
D. It leads to male pseudohermaphroditism. (Correct Answer)

Explanation: ***It leads to male pseudohermaphroditism.*** - **21-Hydroxylase deficiency** does not lead to male pseudohermaphroditism; instead, it causes **virilization in females** (female pseudohermaphroditism) due to increased androgen production. - Males with 21-hydroxylase deficiency typically present with **salt-wasting crises** or **premature pubarche**, but their internal and external genitalia are normal. *It is the most common cause of congenital adrenal hyperplasia.* - This statement is **true**. **21-hydroxylase deficiency** accounts for approximately 90-95% of all cases of congenital adrenal hyperplasia (CAH) [1]. - Its prevalence and significant role in cortisol and aldosterone synthesis pathways make it the predominant form of the disorder [1]. *It is inherited in an autosomal recessive manner.* - This statement is **true**. 21-hydroxylase deficiency is caused by mutations in the **CYP21A2 gene**, which is inherited in an **autosomal recessive pattern**. - Both parents must be carriers for a child to be affected, with each child having a 25% chance of inheriting the disorder. *It leads to female pseudohermaphroditism.* - This statement is **true**. In affected females, the deficiency of 21-hydroxylase shunts steroid precursors towards the **androgen pathway**, leading to excess adrenal androgens. - This excess androgen exposure *in utero* causes **virilization** of external genitalia, resulting in varying degrees of **ambiguous genitalia** (female pseudohermaphroditism).

Question 1673: What is the most common cause of thyroiditis?

A. Reidel's Thyroiditis
B. Subacute Thyroiditis
C. Hashimoto's Thyroiditis (Correct Answer)
D. Viral Thyroiditis

Explanation: ***Hashimoto's Thyroiditis*** - **Hashimoto's thyroiditis** is the most common cause of thyroiditis, characterized by **autoimmune destruction** of the thyroid gland. - It often leads to **hypothyroidism** and is associated with elevated antithyroid antibodies (anti-TPO, anti-Tg). [1] *Riedl' s Thyroiditis* - This is a rare condition characterized by a **fibrous and painless** infiltration of the thyroid gland. - It does not represent the most common cause of thyroiditis and typically presents differently. *Viral thyroiditis* - This form of thyroiditis may occur following a **viral infection** (e.g., mumps) but is not as prevalent as Hashimoto's. - Symptoms are often acute and resolve quickly, differing from the chronic nature of Hashimoto's. *Subacute Thyroiditis* - Subacute thyroiditis, often post-viral, typically causes a **transient** inflammation of the thyroid. [1] - While it can cause significant pain and thyroid hormone fluctuations, it is less common than Hashimoto's thyroiditis.

Question 1674: Which of the following statements is true regarding primary hyperparathyroidism?

A. Adenoma is the most common cause of primary hyperparathyroidism. (Correct Answer)
B. Elevated serum calcium is a key diagnostic criterion.
C. Surgery is indicated for symptomatic patients or those with significant biochemical abnormalities.
D. Parathyroid carcinoma is the most common cause of primary hyperparathyroidism.

Explanation: ***Adenoma is the most common cause of primary hyperparathyroidism.*** [1] - A **solitary parathyroid adenoma** accounts for approximately 85% of all cases of primary hyperparathyroidism. - This benign tumor leads to the **overproduction of parathyroid hormone (PTH)**, resulting in hypercalcemia [2]. *Elevated serum calcium is a key diagnostic criterion.* - While **elevated serum calcium** (hypercalcemia) is a **hallmark** of primary hyperparathyroidism, it is not the *only* diagnostic criterion. - The diagnosis also requires **elevated or inappropriately normal parathyroid hormone (PTH)** levels in the presence of hypercalcemia [3]. *Surgery is indicated for symptomatic patients or those with significant biochemical abnormalities.* - **Surgery (parathyroidectomy)** is indeed the definitive treatment for primary hyperparathyroidism in appropriate candidates, including symptomatic patients or those meeting specific criteria for intervention [1]. - However, labeling this statement as "true regarding primary hyperparathyroidism" in a general sense, while factually correct, does not describe a fundamental characteristic *of the condition itself* but rather its management. The question asks what is true *regarding* the condition, and the most common cause is a more direct answer describing the disease. *Parathyroid carcinoma is the most common cause of primary hyperparathyroidism.* - **Parathyroid carcinoma** is an extremely rare cause of primary hyperparathyroidism, accounting for less than 1% of cases. - It typically presents with **significantly higher calcium and PTH levels** compared to adenomas and is often associated with a palpable neck mass.

Question 1675: Which of the following is the initial investigation of choice for a patient presenting with a solitary nodule of the thyroid?

A. Thyroid function test
B. FNAC (Correct Answer)
C. Radionuclide scan
D. MRI

Explanation: ***FNAC*** - **Fine needle aspiration cytology (FNAC)** is the most important initial investigation for a solitary thyroid nodule to determine if it is benign or malignant. [1] - It offers a highly accurate and minimally invasive method for **cytological analysis** to guide further management. *Thyroid function test* - While important for assessing **thyroid hormone levels** and diagnosing hyper or hypothyroidism, it does not directly evaluate the **malignant potential** of a nodule. [1] - Normal thyroid function does **not rule out malignancy** within a nodule. *Radionuclide scan* - A **radionuclide scan** is useful for assessing the **functional status** of a nodule (hot or cold). [1] - However, non-functional (**cold**) nodules are more suspicious for malignancy, but the scan doesn't provide **histological diagnosis**. *MRI* - **MRI** provides detailed anatomical imaging of the thyroid and surrounding structures but is generally not the **initial diagnostic test of choice** for evaluating a solitary nodule. [1] - It is typically reserved for assessing **nodule extension** or **lymph node involvement** once malignancy is suspected or confirmed. [1]

Question 1676: Foot ulcers in diabetes are due to all except which of the following?

A. Microangiopathy
B. Macroangiopathy
C. Neuropathy
D. Hypoglycemia (Correct Answer)

Explanation: ***Hypoglycemia*** - **Hypoglycemia** refers to abnormally low blood glucose levels and is typically managed by consuming glucose. - It does not directly cause foot ulcers but is a complication of diabetes management [2]. *Neuropathy* - **Diabetic neuropathy** leads to loss of protective sensation, making patients unaware of minor injuries or pressure points on their feet [1]. - This lack of sensation makes the foot vulnerable to repeated trauma and ulceration [2], [3]. *Microangiopathy* - **Microangiopathy** in diabetes affects small blood vessels, impairing blood flow to the skin and peripheral tissues of the feet. - Reduced blood supply compromises tissue healing and increases susceptibility to infection, contributing to ulcer formation [4]. *Macroangiopathy* - **Macroangiopathy** involves large blood vessels, leading to **peripheral artery disease** which reduces blood flow to the feet [1]. - Poor circulation impedes wound healing and increases the risk of infection, making ulcers more likely and harder to treat [3].

Question 1677: What is the best screening test for pheochromocytoma?

A. Clonidine suppression test
B. Serum catecholamine estimation
C. Urinary metanephrine (Correct Answer)
D. Urinary VMA estimation

Explanation: ***Urinary metanephrine*** - **Urinary fractionated metanephrines** (metanephrine and normetanephrine) are catabolites of catecholamines and are now considered the most sensitive and specific screening test for **pheochromocytoma**. - The test involves collecting a **24-hour urine sample** to measure their levels, as their excretion is more constant than that of parent catecholamines. *Urinary VMA estimation* - **Vanillylmandelic acid (VMA)** is a metabolite of catecholamines, but its measurement in urine is generally **less sensitive** and specific than metanephrine measurement for screening pheochromocytoma. - While it can be elevated in pheochromocytoma, there are **more accurate and reliable tests** available. *Serum catecholamine estimation* - **Plasma free metanephrines** are often considered the most sensitive test, but measurement of **serum (or plasma) catecholamines** (epinephrine, norepinephrine, dopamine) can be highly variable due to their pulsatile release and short half-lives. - Levels can be significantly affected by **stress, exercise, and diet**, leading to false positives or negatives, making it less reliable for initial screening than metanephrines. *Clonidine suppression test* - The **clonidine suppression test** is a **confirmatory test**, not a screening test, used when there is biochemical evidence suggestive of pheochromocytoma, but the diagnosis is unclear [1]. - It helps differentiate between essential hypertension with elevated catecholamines and hypertension caused by pheochromocytoma, as clonidine suppresses neurogenically mediated catecholamine release but not release from a tumor [1].

Question 1678: VIPoma is associated with which syndrome?

A. Cushing's syndrome
B. Verner-Morrison syndrome (Correct Answer)
C. Carcinoid syndrome (serotonin syndrome)
D. Zollinger-Ellison syndrome

Explanation: ***Verner-Morrison syndrome*** - **VIPoma** is a neuroendocrine tumor that secretes **vasoactive intestinal peptide (VIP)**, causing symptoms like watery diarrhea, hypokalemia, and achlorhydria (WDHA syndrome) [1]. - This clinical presentation is also known as **Verner-Morrison syndrome**, directly linking the VIPoma to this syndrome [1]. *Cushing's syndrome* - Characterized by excessive **cortisol** production, leading to symptoms like central obesity, moon facies, and hypertension [3]. - This syndrome is not directly associated with VIP excess or the watery diarrhea seen in VIPoma [2]. *Carcinoid syndrome (serotonin syndrome)* - Caused by tumors, typically in the gastrointestinal tract, that produce **serotonin**, leading to flushing, diarrhea, and bronchospasm [1]. - While it involves diarrhea, the primary mediator is serotonin, not VIP, and the other classic VIPoma symptoms (hypokalemia, achlorhydria) are absent [1]. *Zollinger-Ellison syndrome* - Characterized by a **gastrin-producing tumor (gastrinoma)**, which causes excessive gastric acid secretion and severe peptic ulcer disease [4]. - The hormonal excess is **gastrin**, not VIP, and symptoms are related to acid overproduction rather than massive watery diarrhea and hypokalemia [4].

Question 1679: All of the following are seen in MEN 2B except which of the following?

A. Neuromas
B. Pheochromocytoma
C. Medullary carcinoma thyroid
D. Hyperparathyroidism (Correct Answer)

Explanation: ***Hyperparathyroidism*** - **Hyperparathyroidism** is a characteristic feature of **MEN 1** and **MEN 2A**, but it is typically **absent in MEN 2B**. - MEN 2B is primarily associated with **RET gene mutations** that do not commonly lead to parathyroid gland hyperplasia or adenomas. *Neuromas* - **Mucosal neuromas**, particularly in the lips, tongue, and gastrointestinal tract, are a **hallmark feature of MEN 2B**. - These benign tumors are a key diagnostic clue for this syndrome. *Medullary carcinoma thyroid* - **Medullary thyroid carcinoma (MTC)** is a **nearly universal and aggressive component of MEN 2B**, arising from parafollicular C-cells. - It is often the presenting feature and requires early detection and thyroidectomy due to its high metastatic potential. *Pheochromocytoma* - **Pheochromocytoma**, a tumor of the adrenal medulla, occurs in approximately 50-70% of individuals with **MEN 2B**. - It can cause severe hypertension and is an important component of the syndrome that needs to be screened for due to its potential for life-threatening hypertensive crises.

Question 1680: A 24-year-old accountant complains of a white discharge from his breasts. He is most likely experiencing which one of the following conditions?

A. Deficient testosterone receptors in the mammary glands
B. A tumor of the posterior pituitary that could be surgically removed
C. Excessive production of OT in the hypothalamus
D. A prolactinoma (Correct Answer)

Explanation: ***A prolactinoma*** - A **prolactinoma** is a benign tumor of the pituitary gland that secretes **prolactin**, leading to **galactorrhea** (white discharge from the breasts) in both men and women. - In men, high prolactin levels can also cause **hypogonadism**, resulting in **decreased libido** and **erectile dysfunction**. *A tumor of the posterior pituitary that could be surgically removed* - The **posterior pituitary** primarily secretes **oxytocin** and **ADH** (antidiuretic hormone), not prolactin. Tumors here would likely present with symptoms related to these hormones, such as **diabetes insipidus**. - While pituitary tumors can be surgically removed, a **posterior pituitary tumor** is not the typical cause of galactorrhea. *Excessive production of OT in the hypothalamus* - **Oxytocin (OT)** is primarily involved in uterine contractions and milk ejection during lactation, not in milk production or spontaneous galactorrhea. - Excessive OT production would not cause a white discharge from the breasts in a non-lactating individual and is not typically associated with pituitary tumors. *Deficient testosterone receptors in the mammary glands* - **Testosterone receptors** are not directly involved in the production of milk or glandular discharge in mammary tissue. - While hormonal imbalances can affect breast tissue, a deficiency in testosterone receptors would not autonomously cause galactorrhea.

Practice by Chapter

Diabetes Mellitus

Practice Questions

Thyroid Disorders

Practice Questions

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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