Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 1481: A 62-year-old male with a history of hypertension and type 2 diabetes presents with fatigue and weight loss. His blood pressure is 160/100 mmHg. Laboratory tests show elevated aldosterone and low plasma renin activity. What is the most likely diagnosis?

A. Primary hyperaldosteronism (Correct Answer)
B. Cushing's syndrome
C. Pheochromocytoma
D. Secondary hypertension

Explanation: ***Primary hyperaldosteronism*** - The combination of **hypertension**, **elevated aldosterone**, and **low plasma renin activity** [2] is characteristic of primary hyperaldosteronism, where the adrenal glands produce excessive aldosterone independently of the renin-angiotensin system. - While fatigue and weight loss are non-specific, persistent hypertension unresponsive to usual treatments and associated with electrolyte imbalances (though not explicitly mentioned here) further points to this diagnosis. *Cushing's syndrome* - This condition is characterized by **excess cortisol**, leading to symptoms like **central obesity**, **moon facies**, **buffalo hump**, and **striae**, which are not described in the patient's presentation. - While hypertension can occur, the key lab findings of **elevated aldosterone and low renin** are not primary features of Cushing's syndrome [3]. *Pheochromocytoma* - A pheochromocytoma is a tumor that secretes **catecholamines**, causing **paroxysmal hypertension**, **tachycardia**, **palpitations**, **sweating**, and **headaches** [1]. - The characteristic laboratory findings would be **elevated plasma metanephrines or normetanephrines**, not elevated aldosterone or low renin. *Secondary hypertension* - This is a broad category, but the specific lab findings of **elevated aldosterone and low renin** in this patient precisely identify the *cause* of the secondary hypertension as primary hyperaldosteronism. - Without these specific findings, other causes of secondary hypertension (e.g., renal artery stenosis, thyroid dysfunction) would need to be considered [4], but the current data points to a specific etiology.

Question 1482: A 30-year-old patient presents with symptoms of hyperthyroidism, including palpitations and heat intolerance. Which hormone is primarily responsible for these symptoms?

A. Thyroxine (T4)
B. Thyroid-stimulating hormone (TSH)
C. Parathyroid hormone (PTH)
D. Triiodothyronine (T3) (Correct Answer)

Explanation: ***Triiodothyronine (T3)*** - **T3** is the **biologically active form** of thyroid hormone and is several times more potent than T4, directly mediating the effects of hyperthyroidism [1]. - Symptoms like **palpitations** and **heat intolerance** are direct consequences of increased metabolic rate and heightened adrenergic sensitivity driven by elevated T3 [3]. *Thyroxine (T4)* - **Thyroxine (T4)** is the primary hormone secreted by the thyroid gland, but it is largely a **prohormone** that must be converted to T3 to exert its full biological effects. - While elevated T4 is present in hyperthyroidism, the symptoms are primarily mediated by its conversion to T3 at the tissue level. *Thyroid-stimulating hormone (TSH)* - **TSH** is produced by the pituitary gland and *stimulates* the thyroid to produce T3 and T4; in primary hyperthyroidism, TSH levels are typically **suppressed** due to negative feedback [2]. - TSH itself does not directly cause the symptoms of hyperthyroidism but rather regulates the production of the hormones that do. *Parathyroid hormone (PTH)* - **PTH** is involved in **calcium and phosphate homeostasis** and is produced by the parathyroid glands. - It has no direct role in regulating metabolism or causing symptoms of thyroid dysfunction.

Question 1483: A patient presents with polyuria, polydipsia, and dilute urine. Which hypothalamic hormone deficiency is most likely responsible for these symptoms?

A. ADH (antidiuretic hormone) (Correct Answer)
B. Oxytocin
C. GnRH (gonadotropin-releasing hormone)
D. CRH (corticotropin-releasing hormone)

Explanation: ***ADH (antidiuretic hormone)*** - **Deficiency of ADH**, also known as **vasopressin**, leads to **diabetes insipidus**, characterized by the kidneys' inability to reabsorb water, resulting in **polyuria** (excessive urination) and **polydipsia** (excessive thirst) to compensate for fluid loss [1],[2],[3]. - ADH plays a crucial role in maintaining **water balance** by stimulating water reabsorption in the renal tubules; its absence means large volumes of **dilute urine** are excreted [1]. *Oxytocin* - Primarily involved in **uterine contractions** during childbirth and **milk ejection** during lactation. - A deficiency would affect reproductive functions and milk release, not directly cause polyuria or polydipsia. *GnRH (gonadotropin-releasing hormone)* - Stimulates the release of **FSH (follicle-stimulating hormone)** and **LH (luteinizing hormone)** from the pituitary, which are essential for reproductive function. - Deficiency leads to hypogonadism, affecting fertility and sex hormone production, but not water balance. *CRH (corticotropin-releasing hormone)* - Stimulates the release of **ACTH (adrenocorticotropic hormone)** from the pituitary, which in turn regulates the adrenal glands' production of cortisol. - CRH deficiency would impact the stress response and cortisol levels, not fluid and electrolyte balance in the manner described.

Question 1484: A patient presents with hypotension and hyperkalemia. Which endocrine disorder is most likely to be diagnosed?

A. Addison's disease (Correct Answer)
B. Graves' disease (autoimmune hyperthyroidism)
C. Hyperaldosteronism (Conn's syndrome)
D. Cushing's syndrome (adrenal hyperfunction)

Explanation: ***Addison's disease*** - **Addison's disease** (primary adrenal insufficiency) leads to decreased production of **mineralocorticoids** (like aldosterone) and **glucocorticoids** (like cortisol) [1], [2]. - The lack of aldosterone causes impaired sodium reabsorption and potassium excretion in the kidneys, leading to **hypotension** (due to volume depletion) and **hyperkalemia** [1]. *Graves' disease (autoimmune hyperthyroidism)* - **Graves' disease** is characterized by **hyperthyroidism**, which typically presents with symptoms like **tachycardia**, **weight loss**, and **heat intolerance** [3]. - It does not directly cause **hypotension** or **hyperkalemia**; electrolyte imbalances are generally not a primary feature. *Hyperaldosteronism (Conn's syndrome)* - **Hyperaldosteronism** is characterized by **excessive aldosterone secretion**, leading to increased sodium reabsorption and potassium excretion. - This typically results in **hypertension** and **hypokalemia**, which are the opposite of the patient's symptoms [1]. *Cushing's syndrome (adrenal hyperfunction)* - **Cushing's syndrome** is caused by excessive **cortisol levels**, leading to symptoms like **weight gain**, **moon facies**, and **hypertension**. - It does not typically cause **hypotension** or **hyperkalemia**; cortisol excess can, in some cases, have mineralocorticoid effects leading to hypokalemia.

Question 1485: A 60-year-old male with generalized anxiety disorder, stable on an SSRI, presents with tremor, insomnia, and palpitations. Laboratory results show increased FT4 and decreased TSH. Evaluate the management approach.

A. Add propranolol, monitor thyroid function (Correct Answer)
B. Switch SSRI to mirtazapine
C. Switch SSRI to SNRI
D. Lower SSRI dose, add propranolol

Explanation: ***Add propranolol, monitor thyroid function*** - The patient presents with symptoms such as **tremor, insomnia, and palpitations**, along with lab results showing **increased FT4 and decreased TSH**, which are classic signs of **hyperthyroidism**. [1] - **Propranolol**, a beta-blocker, is effective in rapidly alleviating the adrenergic symptoms of hyperthyroidism (e.g., palpitations, tremor, anxiety) while further investigation and definitive treatment for the underlying thyroid condition are pursued. [1] *Switch SSRI to SNRI* - Switching antidepressants would not address the underlying **hyperthyroidism** and its physiological symptoms. - While the patient has a history of anxiety, the current presentation suggests a new **medical condition** rather than solely a psychiatric one requiring an antidepressant change. *Switch SSRI to mirtazapine* - **Mirtazapine** is an antidepressant that would not target the **adrenergic symptoms** or the hormonal imbalance caused by hyperthyroidism. - Switching to an entirely different class of antidepressant in this acute presentation would delay appropriate medical management for the **thyroid dysfunction**. *Lower SSRI dose, add propranolol* - While adding **propranolol** would help with the symptoms, lowering the SSRI dose is not indicated as there is no evidence that the SSRI is causing these new symptoms; the labs clearly point to **hyperthyroidism**. - The patient's **generalized anxiety disorder** is stable on the current SSRI, and dose reduction without a clear reason could exacerbate his anxiety symptoms. [2]

Question 1486: In a patient with suspected pheochromocytoma, which test is essential for diagnosis?

A. Plasma renin activity
B. Blood glucose levels
C. 24-hour urine catecholamines and metanephrines
D. Urine vanillylmandelic acid (VMA) (Correct Answer)

Explanation: ***Urine vanillylmandelic acid (VMA)*** - **VMA** is a major **metabolite of norepinephrine and epinephrine**, and elevated levels in urine are indicative of increased catecholamine production associated with pheochromocytoma. - While other catecholamine metabolites can be measured, VMA has historically been a reliable diagnostic marker, though often combined with metanephrines for higher sensitivity. *24-hour urine catecholamines and metanephrines* - This test measures the total excretion of **norepinephrine, epinephrine**, and their O-methylated metabolites, **metanephrines**, over a 24-hour period [1]. - It is currently considered the most accurate and sensitive biochemical test for diagnosing pheochromocytoma, with plasma-free metanephrines being a strong alternative, but VMA is still highly relevant [1]. *Plasma renin activity* - **Plasma renin activity** measures the amount of **renin**, an enzyme produced by the kidneys, which is involved in blood pressure regulation. - This test is primarily used in the diagnosis of **primary aldosteronism** and **renovascular hypertension**, not pheochromocytoma [1]. *Blood glucose levels* - While **catecholamines** can cause **hyperglycemia** by increasing glycogenolysis and gluconeogenesis, measuring blood glucose is a non-specific test for pheochromocytoma. - Elevated blood glucose levels could be due to numerous other conditions, such as **diabetes mellitus**, and are not diagnostic for pheochromocytoma.

Question 1487: A patient presents with polyuria, polydipsia, and hyperglycemia. Which diagnostic test would best confirm the diagnosis of diabetes mellitus?

A. Oral glucose tolerance test
B. Random blood glucose test
C. HbA1c test
D. Fasting blood glucose test (Correct Answer)

Explanation: ***Fasting blood glucose test*** - A **fasting plasma glucose (FPG)** level of **≥ 126 mg/dL (7.0 mmol/L)** on two separate occasions is diagnostic for diabetes mellitus [1]. - It directly measures the body's ability to regulate glucose after a period of fasting, making it highly specific for diagnosing diabetes [1]. *Oral glucose tolerance test* - While definitive, the **oral glucose tolerance test (OGTT)** is more cumbersome and time-consuming, requiring multiple blood draws after ingesting a glucose solution. - It is typically used when fasting glucose results are equivocal or to diagnose **gestational diabetes**, rather than as a primary confirmation in this scenario. *HbA1c test* - An **HbA1c level of ≥ 6.5%** is diagnostic of diabetes, reflecting average blood glucose levels over the preceding 2-3 months. - However, it can be affected by conditions altering red blood cell lifespan (e.g., anemia, hemoglobinopathies), which might lead to inaccurate results in some patients. *Random blood glucose test* - A **random plasma glucose** **≥ 200 mg/dL (11.1 mmol/L)** in a patient with classic symptoms of hyperglycemia (polyuria, polydipsia) is suggestive of diabetes [1]. - While useful for initial screening or in symptomatic patients, it does not provide the same level of diagnostic confirmation as a fasting or OGTT.

Question 1488: In a patient with newly diagnosed type 1 diabetes, which antibody is most likely to be positive?

A. Anti-glutamic acid decarboxylase (anti-GAD) antibody (Correct Answer)
B. Anti-islet cell antibodies
C. Anti-insulin autoantibodies
D. Anti-thyroid peroxidase antibodies

Explanation: ***Anti-glutamic acid decarboxylase (anti-GAD) antibody*** - **Anti-GAD antibodies** are the most common and often the **first detectable autoantibody** in new-onset type 1 diabetes, present in about 70-80% of patients. - They target an enzyme found in the pancreatic beta cells, playing a crucial role in the **autoimmune destruction** leading to insulin deficiency [1]. *Anti-insulin autoantibodies* - While present in type 1 diabetes, **anti-insulin autoantibodies (IAA)** are more common in **younger children** and those who have not yet received exogenous insulin. - Their presence often declines with age and insulin treatment, making GAD antibodies generally more prevalent in newly diagnosed patients across all age groups. *Anti-islet cell antibodies* - **Islet cell antibodies (ICAs)** are a panel of antibodies targeting various components of pancreatic islet cells, including GAD [1]. - While ICAs are predictive of type 1 diabetes, the anti-GAD antibody is a more specific and frequently tested individual marker within this broader category. *Anti-thyroid peroxidase antibodies* - **Anti-thyroid peroxidase (anti-TPO) antibodies** are markers for **autoimmune thyroid diseases** (e.g., Hashimoto's thyroiditis), not type 1 diabetes. - Although type 1 diabetes can co-exist with other autoimmune conditions like thyroid disease [1], anti-TPO antibodies are not directly involved in the pathogenesis or diagnosis of type 1 diabetes itself.

Question 1489: What is the primary metabolic disorder that characteristically causes severe hypertriglyceridemia?

A. Familial hypercholesterolemia
B. Familial chylomicronemia syndrome (Correct Answer)
C. Type 2 diabetes mellitus
D. Hypothyroidism

Explanation: ***Familial chylomicronemia syndrome*** - This syndrome is characterized by a severe deficiency in **lipoprotein lipase (LPL)** activity or its cofactors, leading to the accumulation of **chylomicrons** in the bloodstream [1]. - The inability to clear chylomicrons results in extremely high **triglyceride levels**, often exceeding 1000 mg/dL, which can cause pancreatitis and eruptive xanthomas [1]. *Familial hypercholesterolemia* - This genetic disorder primarily affects the metabolism of **low-density lipoprotein (LDL) cholesterol**, leading to very high **LDL levels** [2]. - While it can be associated with some increase in triglycerides, **hypertriglyceridemia** is not its primary or characteristic feature [1]. *Type 2 diabetes mellitus* - Poorly controlled **Type 2 diabetes** can cause **secondary hypertriglyceridemia** due to increased very-low-density lipoprotein (VLDL) production and impaired triglyceride clearance [3]. - However, it's a secondary cause and often does not reach the extremely high levels seen in primary chylomicronemia syndromes unless compounded by other factors. *Hypothyroidism* - **Hypothyroidism** can lead to **dyslipidemia**, primarily characterized by elevated **LDL cholesterol** and moderately elevated **triglycerides** due to decreased LPL activity and slower chylomicron clearance. - While it can cause hypertriglyceridemia, the severity typically does not approximate the extreme levels seen in familial chylomicronemia syndrome.

Question 1490: A 35-year-old woman with a goiter presents with difficulty swallowing and an ultrasound revealing a 3 cm nodule. What is the most appropriate management?

A. Thyroid hormone suppression therapy
B. Ultrasound-guided fine needle aspiration (Correct Answer)
C. Total thyroidectomy
D. Observation and ultrasound follow-up in 6 months

Explanation: Ultrasound-guided fine-needle aspiration (FNA) - A 3 cm thyroid nodule in a 35-year-old woman, especially with difficulty swallowing (a compressive symptom), warrants further investigation to rule out malignancy [1]. - FNA is the most appropriate initial step for diagnosis, as it can differentiate between benign and malignant lesions and guide subsequent management [1]. Thyroid hormone suppression therapy - This therapy is primarily used to shrink benign, autonomously functioning nodules or to suppress TSH in cases of differentiated thyroid cancer post-surgery [1]. - It is not indicated as an initial diagnostic step for a new, symptomatic thyroid nodule, especially one with compressive symptoms, before malignancy has been ruled out [1]. Total thyroidectomy - Total thyroidectomy is a definitive surgical treatment, typically reserved for confirmed thyroid cancer or large, symptomatic benign goiters refractory to other treatments [1]. - Performing a total thyroidectomy without a definitive diagnosis from FNA would be premature and potentially an overtreatment if the nodule proves benign. Observation and ultrasound follow-up in 6 months - Observation with follow-up is generally appropriate for smaller, asymptomatic thyroid nodules (<1 cm or 1-1.5 cm depending on risk factors and ultrasound features) with benign characteristics. - A 3 cm nodule causing dysphagia is considered high-risk and requires immediate diagnostic evaluation rather than delayed follow-up [1].

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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