Endocrinology — MCQs

A 20-year-old female presents with increasing hair growth on her face and chest, deepening of her voice, and acne over the past year. She has no history of other medical problems. On examination, she has acne, abnormal male pattern balding, and enlargement of her clitoris. Blood tests show normal serum testosterone levels but a markedly elevated level of dihydroepiandrosterone sulphate. What is the most likely diagnosis?

Q1686

A common finding in osteomalacia is

Q1687

A middle-aged female presents with increasing visual loss, breast enlargement, and irregular menses. What is the most appropriate investigation to diagnose the underlying condition?

Q1688

Which of the following is NOT consistent with pheochromocytoma?

Q1689

All of the following are features of hypothyroidism except which of the following?

Q1690

Which of the following glands is NOT involved in Type I MEN?

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 1681: 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 1682: What percentage of cold thyroid nodules are malignant?

A. 70-80%
B. 50-60%
C. 40-50%
D. 10-20% (Correct Answer)

Explanation: ***10-20%*** - While a **cold thyroid nodule** indicates reduced or absent uptake of radioactive iodine, suggesting a non-functional status, the vast majority are **benign** [1]. - A malignancy rate of **10-20%** is consistent with current epidemiological data for these nodules [1]. *70-80%* - This percentage is **significantly higher** than the actual malignancy rate observed in cold thyroid nodules. - Such a high rate would imply that most cold nodules are cancerous, which is **not true** clinically [1]. *50-60%* - This range is a substantial **overestimation** of the malignancy risk associated with cold thyroid nodules. - If half or more of cold nodules were malignant, the clinical approach to their management would be **much more aggressive** [1]. *40-50%* - This percentage is also a **considerable overestimation** and does not reflect the typical malignancy rate. - Thyroid nodules, even cold ones, are far more frequently **benign** than malignant [1].

Question 1683: The most common cause of hyperthyroidism in a young female is?

A. TSH-secreting pituitary adenoma
B. Graves' disease (Correct Answer)
C. Subacute thyroiditis
D. Toxic multinodular goiter

Explanation: ***Graves' disease*** - This is an **autoimmune disorder** where antibodies stimulate the thyroid gland, leading to **overproduction of thyroid hormones** [1], [2]. - It is the **most common cause of hyperthyroidism** in young to middle-aged women, making it highly probable in a young female patient [1], [2]. *Toxic multinodular goiter* - This condition is characterized by **multiple nodules** within the thyroid gland that autonomously produce thyroid hormones. - While a cause of hyperthyroidism, it is **more common in older individuals**, typically those over 50 years of age. *Subacute thyroiditis* - This is a **self-limiting inflammatory condition** of the thyroid often following a viral infection, causing a transient hyperthyroid phase due to the release of preformed hormones. - It presents with **painful thyroid enlargement** and is usually followed by a hypothyroid phase, which is different from sustained hyperthyroidism. *TSH-secreting pituitary adenoma* - This is a **very rare cause of hyperthyroidism** where a pituitary tumor produces excess **Thyroid-Stimulating Hormone (TSH)**, leading to thyroid overstimulation. - It is often accompanied by other symptoms of a pituitary mass like **headaches or visual field defects**, which are not implied here.

Question 1684: In Klinefelter syndrome, which of the following statements is false?

A. Negative feedback on FSH and LH is lost
B. Increased Androstenedione levels
C. Hypoplastic male external genitalia (Correct Answer)
D. Most common cause of secondary testicular failure

Explanation: ***Hypoplastic male external genitalia*** - This statement is false because individuals with **Klinefelter syndrome** typically have **normal male external genitalia**, though the testes are usually small and firm [1], [2]. - The condition is characterized by the presence of an extra X chromosome (47, XXY), which affects testicular development, leading to **dysgenesis of the seminiferous tubules** and subsequent hormonal imbalances [2]. *Negative feedback on FSH and LH is lost* - This statement is true because the **dysfunctional testes** in Klinefelter syndrome produce very little **inhibin** and **testosterone**. - This lack of negative feedback to the pituitary results in **elevated levels of FSH and LH** [2]. *Increased Androstenedione levels* - This statement is true, although it is an indirect effect. In Klinefelter syndrome, there is **hypergonadotropic hypogonadism** which leads to an increase in **gonadotropins (LH and FSH)** [3]. - Increased LH can stimulate adrenal production of **androstenedione**, and peripheral aromatization of androstenedione can contribute to higher estrogen levels typical in these patients. *Most common cause of secondary testicular failure* - This statement is true; Klinefelter syndrome is considered the most common genetic cause of **primary hypogonadism**. - Testicular failure in Klinefelter syndrome is usually primary (due to testicular dysfunction), but the hormonal dysregulation can lead to secondary effects [3].

Question 1685: A 20-year-old female presents with increasing hair growth on her face and chest, deepening of her voice, and acne over the past year. She has no history of other medical problems. On examination, she has acne, abnormal male pattern balding, and enlargement of her clitoris. Blood tests show normal serum testosterone levels but a markedly elevated level of dihydroepiandrosterone sulphate. What is the most likely diagnosis?

A. Polycystic Ovary Syndrome (PCOS)
B. Adrenal Tumor (Correct Answer)
C. Ovarian Tumor
D. Drug Induced Adverse Effects

Explanation: ***Adrenal Tumor*** - The combination of **rapid onset virilization** (deepening voice, male pattern balding, clitoromegaly) and **markedly elevated DHEAS** points strongly to an adrenal source of androgens, typically an adrenal tumor. - **DHEAS** is almost exclusively produced by the **adrenal glands**, making its high levels a key indicator of adrenal pathology [1]. *Polycystic Ovary Syndrome (PCOS)* - While PCOS can cause **hirsutism** and **acne**, it usually presents with milder virilization and elevated testosterone, not typically with severe features like **clitoromegaly** or significantly elevated DHEAS [1]. - The onset in PCOS is usually more gradual, and **DHEAS levels** are typically normal or only mildly elevated, with **testosterone** being the predominant elevated androgen [1]. *Ovarian Tumor* - Ovarian tumors can cause **virilization** due to androgen production, but they primarily lead to **elevated testosterone levels**, not usually markedly elevated DHEAS [1]. - The **rapid progression of virilization** could be consistent with an ovarian tumor, but the specific DHEAS elevation makes an adrenal source more likely. *Drug Induced Adverse Effects* - Certain medications can cause symptoms like **acne** or **hirsutism**, but it's rare for drugs to induce such a full spectrum of **virilization** including **clitoromegaly** and **deepening voice** without other clear drug history. - Drug-induced virilization would not specifically cause a **markedly elevated DHEAS** level with normal testosterone, which points to an endogenous androgen-producing pathology.

Question 1686: A common finding in osteomalacia is

A. Low serum phosphate
B. Normal hydroxy proline levels in urine
C. Normal level of 1, 25 di-hydroxy vit D3
D. Low serum calcium (Correct Answer)

Explanation: ***Low serum calcium*** - **Osteomalacia** is characterized by defective **bone mineralization**, often due to vitamin D deficiency, which leads to impaired calcium absorption and subsequent **hypocalcemia** [1]. - To compensate for low serum calcium, **parathyroid hormone (PTH)** levels increase, further contributing to altered bone metabolism [1]. *Low serum phosphate* - While osteomalacia often features **hypophosphatemia**, it is not always the primary or most consistent finding, as **calcium** dysregulation is central to the disease [1]. - **Secondary hyperparathyroidism** in some cases of osteomalacia can lead to increased phosphate excretion, causing low phosphate, but **hypocalcemia** is more directly related to the mineralization defect [1]. *Normal level of 1, 25 di-hydroxy vit D3* - **1,25-dihydroxyvitami n D3** (calcitriol) levels are typically **low** in nutritional osteomalacia, as this is the active form crucial for calcium absorption and bone mineralization [1]. - Normal levels would contradict the underlying pathology of vitamin D deficiency that causes the condition. *Normal hydroxy proline levels in urine* - **Hydroxyproline** is an amino acid found in collagen, and its urinary excretion reflects **bone turnover**; in osteomalacia, due to defective mineralization and sometimes increased bone resorption, hydroxyproline levels can be elevated or altered. - Normal levels would not be expected given the significant bone metabolic disturbances in osteomalacia.

Question 1687: A middle-aged female presents with increasing visual loss, breast enlargement, and irregular menses. What is the most appropriate investigation to diagnose the underlying condition?

A. S. calcitonin
B. S. prolactin (Correct Answer)
C. S. hemoglobin concentration
D. S. calcium

Explanation: ***S. prolactin*** - **Hyperprolactinemia** is the most likely cause of the presented symptoms: **galactorrhea** (**breast enlargement** with milk production), **amenorrhea** (**irregular menses**), and **visual field defects** due to a pituitary tumor compressing the optic chiasm [1]. - Measuring serum prolactin levels directly confirms or rules out **hyperprolactinemia**, guiding further management, including imaging of the pituitary gland if elevated [1]. *S. calcitonin* - **Calcitonin** is a hormone primarily involved in **calcium regulation** and is typically elevated in medullary thyroid carcinoma. - The presented symptoms (visual loss, breast enlargement, irregular menses) are not characteristic of elevated calcitonin levels or a **medullary thyroid carcinoma**. *S. hemoglobin concentration* - **Hemoglobin concentration** measures the amount of oxygen-carrying protein in red blood cells and is used to diagnose **anemia** or polycythemia. - While general labs might include this, it is not directly relevant to the specific constellation of symptoms pointing towards an **endocrine or pituitary issue**. *S. calcium* - **Serum calcium** levels are checked for disorders of calcium metabolism, such as **hyperparathyroidism** or hypocalcemia. - Though calcium is regulated by hormones, the symptoms of **visual loss**, **breast enlargement**, and **menstrual irregularities** are not typically associated with primary disturbances in calcium levels.

Question 1688: Which of the following is NOT consistent with pheochromocytoma?

A. Episodic diarrhea (Correct Answer)
B. Paroxysm, palpitation and sweating
C. Episodic flushing of skin
D. Episodes of hypertension

Explanation: Episodic diarrhea - While pheochromocytoma can cause gastrointestinal symptoms due to **catecholamine excess**, **diarrhea** is not a classic or consistent feature; constipation or abdominal pain are more commonly reported. - **Vasoactive intestinal peptide (VIP)**-secreting tumors (VIPomas) are more typically associated with chronic watery diarrhea [1]. *Episodic flushing of skin* - **Flushing** can occur in pheochromocytoma due to the **vasodilatory effects** of excessive catecholamines, particularly epinephrine. - It's a common symptom often seen alongside other classic paroxysmal episodes. *Paroxysm, palpitation and sweating* - These are classic components of the **"PHEochromocytoma triad"**: **Palpitations**, **Headache**, and **Episodic sweating**, commonly occurring in paroxysms. - They result directly from the release of large amounts of **norepinephrine and epinephrine** from the tumor. *Episodes of hypertension* - **Episodic or paroxysmal hypertension** is a hallmark symptom of pheochromocytoma, caused by the sudden surge of catecholamines leading to vasoconstriction. - This can manifest as severe, sudden increases in blood pressure, often accompanied by other symptoms like headache and palpitations.

Question 1689: All of the following are features of hypothyroidism except which of the following?

A. Dry skin
B. Myxedema
C. Cold intolerance
D. Lid retraction (Correct Answer)

Explanation: ***Lid retraction*** - **Lid retraction** is a characteristic feature of **hyperthyroidism** (e.g., Graves' disease), not hypothyroidism [1]. - It results from increased sympathetic stimulation of the **Müller's muscle** and/or superior rectus muscle overactivity. *Cold intolerance* - **Cold intolerance** is a common symptom of **hypothyroidism** due to a reduced metabolic rate and decreased heat production [2]. - The body's ability to maintain core temperature is impaired, leading to increased sensitivity to cold environments. *Dry skin* - **Dry, scaly skin** (xerosis) is a frequent manifestation of **hypothyroidism**. - It is caused by decreased sebaceous and sweat gland activity, as well as changes in epidermal cell turnover. *Myxedema* - **Myxedema** refers to the characteristic non-pitting edema seen in severe or long-standing **hypothyroidism** [2]. - It results from the accumulation of **glycosaminoglycans** (e.g., hyaluronic acid) in the interstitial spaces, leading to swelling, particularly in the face, hands, and feet [1].

Question 1690: Which of the following glands is NOT involved in Type I MEN?

A. Parathyroid
B. Adrenal (Correct Answer)
C. Pituitary
D. Pancreas

Explanation: ***Adrenal*** - The **adrenal glands** are predominantly involved in **Multiple Endocrine Neoplasia type 2 (MEN2)**, particularly with pheochromocytomas, rather than MEN type 1. - While adrenal lesions (e.g., adenomas, hyperplasia) can occur sporadically or rarely in MEN1, they are not considered a primary or core component of the MEN1 syndrome as defined by the classic "3 Ps." [1] *Pancreas* - The **pancreas** is a primary gland involved in MEN1, frequently developing **neuroendocrine tumors** (e.g., gastrinomas, insulinomas). - These pancreatic tumors are a major cause of morbidity and mortality in MEN1 patients. *Pituitary* - The **pituitary gland** is one of the classic "3 P's" involved in MEN1, commonly developing **adenomas**, especially **prolactinomas**. [1] - These pituitary tumors can cause hormonal imbalances and mass effects within the sella turcica. *Parathyroid* - The **parathyroid glands** are almost universally involved in MEN1, with **hyperplasia** leading to **primary hyperparathyroidism**. [1] - This is often the earliest and most common clinical manifestation of MEN1.

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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