Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 1491: A patient presents with nocturnal muscle cramps and a recent onset of hypertension. Which endocrine disorder should be considered?

A. Primary hyperparathyroidism
B. Hyperthyroidism
C. Pheochromocytoma (Correct Answer)
D. Cushing's syndrome

Explanation: ***Pheochromocytoma*** - **Pheochromocytoma** can cause episodic hypertension, often associated with symptoms like **palpitations**, headache, and **sweating**, which can manifest as nocturnal events or muscle cramps due to catecholamine surge. - The elevated **catecholamines** lead to vasoconstriction and increased cardiac output, resulting in hypertension and potentially **muscle disturbances**. *Hyperthyroidism* - While hyperthyroidism can cause hypertension, it typically presents with symptoms like **weight loss**, heat intolerance, **tachycardia**, and nervousness, rather than nocturnal muscle cramps as a primary complaint. - Muscle weakness and fatigue are more common in hyperthyroidism than cramps. *Primary hyperparathyroidism* - Primary hyperparathyroidism primarily affects **calcium metabolism**, leading to hypercalcemia; symptoms include **fatigue**, kidney stones, and bone pain. - Hypertension can be present, but **muscle cramps** are not a typical or prominent feature, and muscle weakness or bone-related issues are more characteristic. *Cushing's syndrome* - **Cushing's syndrome** is characterized by symptoms like central obesity, moon facies, striae, and **proximal muscle weakness**, all due to excess cortisol. - Although hypertension is common, nocturnal muscle cramps are not a hallmark symptom of **Cushing's syndrome**, and the muscle weakness is usually distinct from cramping.

Question 1492: A 45-year-old patient presents with muscle weakness and hyperpigmentation. Which condition is indicated by increased ACTH levels?

A. Cushing's disease
B. Addison's disease (Correct Answer)
C. Secondary hyperparathyroidism
D. Pheochromocytoma

Explanation: ***Addison's disease*** - **Addison's disease** (primary adrenal insufficiency) leads to decreased cortisol production, which in turn causes a **compensatory increase in ACTH** [1]. - **High ACTH** stimulates melanocytes, resulting in characteristic **hyperpigmentation** along with symptoms of adrenal insufficiency like muscle weakness [1]. *Cushing's disease* - Cushing's disease is caused by an **ACTH-producing pituitary adenoma**, leading to **excessive cortisol production** [2]. - While ACTH levels are high, the primary presentation is typically **Cushingoid features** (e.g., central obesity, moon facies), and **hyperpigmentation** is less prominent than in Addison's disease. *Secondary hyperparathyroidism* - This condition involves **excessive parathyroid hormone (PTH)** secretion in response to hypocalcemia or vitamin D deficiency, unrelated to ACTH. - Symptoms are primarily related to **bone and mineral metabolism**, not muscle weakness nor hyperpigmentation caused by ACTH. *Pheochromocytoma* - A pheochromocytoma is a tumor of the adrenal medulla that secretes **catecholamines** (epinephrine and norepinephrine). - It causes symptoms like **hypertension, palpitations, and headaches**, and has no direct relationship with ACTH levels, muscle weakness, or hyperpigmentation.

Question 1493: A 40-year-old female experiences muscle fatigue and cramping during exercise. Which metabolic condition is most likely contributing to her symptoms?

A. Hypokalemia (Correct Answer)
B. Hypocalcemia
C. Hyperkalemia
D. Hypercalcemia

Explanation: ***Hypokalemia*** - **Low potassium levels** can lead to impaired muscle contraction and relaxation, causing **muscle fatigue** and **cramping**, especially during exercise. - Potassium plays a crucial role in maintaining the **resting membrane potential** of muscle cells and nerve transmission. *Hypocalcemia* - Characterized by **decreased serum calcium**, which typically presents with **tetany**, **muscle spasms**, and paresthesias. - While it can cause muscle issues, the primary symptoms are often more severe and include excitability of nerves, not just fatigue and cramping. *Hyperkalemia* - Involves **elevated potassium levels**, which can result in **muscle weakness**, paralysis, and potentially life-threatening cardiac arrhythmias. - It does not typically manifest as exercise-induced fatigue and cramping, but rather a more generalized and persistent weakness. *Hypercalcemia* - Characterized by **elevated serum calcium** levels, which often lead to symptoms like **muscle weakness**, lethargy, and constipation. - It tends to cause generalized muscle weakness rather than specific exercise-induced fatigue and cramping.

Question 1494: A 30-year-old female with a goiter has an elevated level of thyroid-stimulating hormone (TSH). What is the likely cause of her condition?

A. Hyperthyroidism
B. Hypothyroidism (Correct Answer)
C. Thyroid neoplasm
D. Iodine sufficiency

Explanation: **Hypothyroidism** - An **elevated TSH** in the presence of a **goiter** is characteristic of **primary hypothyroidism**, where the thyroid gland is failing to produce enough thyroid hormones [1]. - The high TSH stimulates the thyroid gland, attempting to compensate for low thyroid hormone levels, leading to its enlargement (**goiter**) [2]. *Hyperthyroidism* - **Hyperthyroidism** is associated with **low or suppressed TSH** levels because the excessive thyroid hormones feedback negatively on the pituitary gland [1]. - While a goiter can occur, it's typically due to **Grave's disease** (which would have low TSH) or toxic multinodular goiter, not primary hypothyroidism. *Thyroid neoplasm* - A **thyroid neoplasm** (cancer) can sometimes present with a goiter or nodule, but it doesn't directly cause an elevated TSH unless it infiltrates and destroys normal thyroid tissue, leading to hypothyroidism. - Many thyroid cancers are found in euthyroid or hyperthyroid patients. *Iodine sufficiency* - **Iodine sufficiency** is the optimal amount of iodine for normal thyroid function and would typically not cause either a goiter or elevated TSH. - An elevated TSH with a goiter is often seen in **iodine deficiency**, which leads to hypothyroidism, not iodine sufficiency.

Question 1495: A 40-year-old woman presents with fatigue, muscle weakness, and skin hyperpigmentation. Laboratory tests reveal hyponatremia and hyperkalemia. Which test would be most helpful in confirming the suspected diagnosis?

A. Morning cortisol level (Correct Answer)
B. Thyroid function tests
C. Serum aldosterone level
D. Blood urea nitrogen

Explanation: Morning cortisol level - **Adrenal insufficiency** (Addison's disease) is characterized by reduced **cortisol** production, leading to symptoms like **fatigue**, **muscle weakness**, and **hyperpigmentation** [1], [3]. - **Hyponatremia** and **hyperkalemia** are also classic features of adrenal insufficiency due to deficient **aldosterone**, making a **low morning cortisol level** the most direct and crucial diagnostic test [1]. *Thyroid function tests* - While **fatigue** can be a symptom of **thyroid dysfunction**, this option does not explain the **hyperpigmentation**, **hyponatremia**, or **hyperkalemia**. - **Hypothyroidism** can cause **fatigue** and muscle weakness, but it typically presents with **constipation**, **weight gain**, and **dry skin**, not **hyperpigmentation** or electrolyte imbalances seen here [2]. *Serum aldosterone level* - A **low serum aldosterone level** would be consistent with adrenal insufficiency, but it is typically ordered *after* an initial screening test like morning cortisol or ACTH stimulation test confirms adrenal dysfunction [1]. - Measuring **aldosterone** alone is less specific for primary adrenal insufficiency, as it can also be affected by other conditions, and **cortisol** deficiency is typically part of the presenting picture. *Blood urea nitrogen* - **Blood urea nitrogen (BUN)** is a marker of **kidney function** and **hydration status**, which might be elevated in cases of dehydration or kidney injury associated with severe illness. - While electrolyte imbalances can indirectly affect kidney function, measuring **BUN** does not directly assess adrenal function or confirm the suspected diagnosis in this context.

Question 1496: A 45-year-old woman with a history of hypertension is found to have a high plasma aldosterone level. Which condition is most likely present?

A. Primary hyperaldosteronism (Correct Answer)
B. Hypothyroidism
C. Addison's disease
D. Pheochromocytoma

Explanation: ***Primary hyperaldosteronism*** - This condition is characterized by **excessive aldosterone production** directly from the adrenal glands, leading to **hypertension** and often **hypokalemia**. A high plasma aldosterone level in a hypertensive patient strongly points to this diagnosis. - The adrenal glands autonomously secrete aldosterone, uninhibited by the **renin-angiotensin system**. *Hypothyroidism* - This condition involves **insufficient thyroid hormone production**, which typically presents with symptoms such as fatigue, weight gain, and cold intolerance [1]. - While it can indirectly affect blood pressure, it does not directly cause primary elevation of **plasma aldosterone levels**. *Addison's disease* - This is a condition of **adrenal insufficiency**, meaning the adrenal glands produce **insufficient cortisol and aldosterone** [2]. - Therefore, patients with Addison's disease would have **low plasma aldosterone levels**, not high. *Pheochromocytoma* - This is a tumor of the adrenal medulla that secretes **catecholamines** (epinephrine and norepinephrine), leading to paroxysmal or sustained **hypertension**. - While it causes hypertension, it does not directly lead to primary elevation of **aldosterone levels** [3].

Question 1497: A 45-year-old female presents with fatigue, hypotension, hyperpigmentation, hyponatremia, and hyperkalemia, and has a history of autoimmune disorders. What is the likely cause?

A. Adrenal insufficiency leading to cortisol and aldosterone deficiency (Correct Answer)
B. Hypothyroidism resulting in decreased metabolic rate and electrolyte imbalance
C. Parathyroid hormone dysregulation affecting calcium and sodium homeostasis
D. Pituitary adenoma causing ACTH hypersecretion and electrolyte disturbance

Explanation: ***Adrenal insufficiency leading to cortisol and aldosterone deficiency*** - The combination of **fatigue, hypotension, hyperpigmentation, hyponatremia, and hyperkalemia** is classic for **primary adrenal insufficiency** (Addison's disease), often autoimmune in origin [1], [2]. - **Cortisol deficiency** contributes to fatigue and hypotension, while **aldosterone deficiency** leads to potassium retention (hyperkalemia) and sodium loss (hyponatremia) [1]. **Hyperpigmentation** results from increased ACTH and melanocyte-stimulating hormone (MSH) due to lack of negative feedback from cortisol [3]. *Hypothyroidism resulting in decreased metabolic rate and electrolyte imbalance* - While **fatigue** and **hyponatremia** can be seen in **hypothyroidism**, it does not typically cause **hyperpigmentation** or **hyperkalemia**. - **Hypotension** is less common in hypothyroidism; **hypertension** is more frequently observed. *Parathyroid hormone dysregulation affecting calcium and sodium homeostasis* - **Parathyroid hormone dysregulation** primarily affects **calcium and phosphorus metabolism**, leading to symptoms like bone pain, kidney stones, or tetany. - It does not explain the full constellation of symptoms, particularly **hyperpigmentation, hypotension, hyponatremia, and hyperkalemia**. *Pituitary adenoma causing ACTH hypersecretion and electrolyte disturbance* - A **pituitary adenoma causing ACTH hypersecretion** (Cushing's disease) leads to **excess cortisol**, presenting with central obesity, moon facies, striae, and often **hypertension and hypokalemia**, which are opposite to the symptoms described. - While it can cause some electrolyte disturbances, it typically results in **hypernatremia and hypokalemia** due to mineralocorticoid effects of high cortisol, not hyponatremia and hyperkalemia [4].

Question 1498: A 40-year-old male with generalized anxiety disorder on an SSRI presents with fatigue, weight gain, and cold intolerance. Physical examination reveals dry skin and bradycardia. Laboratory results show elevated TSH and decreased FT4. Evaluate the situation and determine the treatment.

A. Add levothyroxine (Correct Answer)
B. Refer to an endocrinologist for further evaluation.
C. Add a triiodothyronine (T3) supplement.
D. Evaluate for SSRI-induced hypothyroidism and consider dose adjustment.

Explanation: A 40-year-old male with generalized anxiety disorder on an SSRI presents with fatigue, weight gain, and cold intolerance. Physical examination reveals dry skin and bradycardia. Laboratory results show elevated TSH and decreased FT4. Evaluate the situation and determine the treatment. ***Add levothyroxine*** - The patient's symptoms (fatigue, weight gain, cold intolerance, dry skin, bradycardia) combined with laboratory findings of **elevated TSH** and **decreased free T4 (FT4)** are definitive for **primary hypothyroidism** [1]. - **Levothyroxine** is the synthetic form of **thyroxine (T4)** and is the standard and most effective treatment for hypothyroidism, replacing the deficient thyroid hormone [1]. *Add a triiodothyronine (T3) supplement.* - While T3 is the active form of thyroid hormone, **T4 (levothyroxine)** is primarily used for treatment because it has a longer half-life and is converted to T3 as needed by the body [1]. - Adding T3 is generally not recommended as initial monotherapy or in addition to T4 for standard hypothyroidism due to potential for **fluctuating levels** and side effects. *Refer to an endocrinologist for further evaluation.* - The diagnosis of **primary hypothyroidism** is clear based on the clinical presentation and laboratory results (high TSH, low FT4). - While an endocrinologist can manage the condition, a referral is not immediately necessary for diagnosis or initiation of treatment, which can often be managed by a primary care physician. *Evaluate for SSRI-induced hypothyroidism and consider dose adjustment.* - Although SSRIs can rarely cause mild thyroid dysfunction, the patient's severe symptoms and clear lab findings (significantly elevated TSH, decreased FT4) point to **clinical hypothyroidism**, not merely drug-induced subclinical changes [2]. - The primary action in such a case is to treat the hypothyroidism, not to assume the SSRI is the direct cause requiring dose adjustment of the antidepressant.

Question 1499: A 50-year-old woman with a history of thyroidectomy presents with hypocalcemia, and her serum calcium level is 6.5 mg/dL. What is the appropriate management plan?

A. Oral calcium supplementation
B. Intravenous calcium gluconate (Correct Answer)
C. Vitamin D supplementation
D. Observation

Explanation: ***Intravenous calcium gluconate*** - A critically low serum calcium level of 6.5 mg/dL warrants **immediate correction** to prevent severe complications such as seizures or cardiac arrhythmias [1]. - **Intravenous calcium gluconate** is the preferred treatment for acute severe hypocalcemia due to its rapid onset of action. *Oral calcium supplementation* - **Oral calcium supplementation** is typically used for chronic, less severe hypocalcemia or as maintenance therapy after acute correction. - It would be **insufficiently rapid** to address the acute, symptomatic hypocalcemia in this patient. *Vitamin D supplementation* - **Vitamin D supplementation** is important for calcium absorption and metabolism, especially in conditions causing chronic hypocalcemia, but it has a slow onset of action [1]. - It is **not the primary treatment** for acute, severe hypocalcemia requiring immediate intervention. *Observation* - A serum calcium level of 6.5 mg/dL is **dangerously low** and can lead to life-threatening complications. - **Observation alone** is inappropriate and would put the patient at significant risk.

Question 1500: A 38-year-old woman presents with headache, visual changes, and hormone imbalance. MRI shows a sellar mass with suprasellar extension and optic chiasm compression. Laboratory results indicate high prolactin levels. What is the likely diagnosis?

A. Meningioma
B. Pituitary adenoma (Correct Answer)
C. Craniopharyngioma
D. Metastatic lesion

Explanation: ***Pituitary adenoma*** - The combination of a **sellar mass with suprasellar extension**, **optic chiasm compression** (leading to visual changes) [1], **hormone imbalance** (high prolactin) [3], and headache is highly characteristic of a **pituitary adenoma** [3]. - **Prolactinomas** are the most common type of pituitary adenoma and directly cause elevated prolactin levels, explaining the hormone imbalance [4]. *Meningioma* - While meningiomas can cause headaches and visual changes due to mass effect, they typically arise from the **meninges** and are less commonly located predominantly in the sella. - They are generally not associated with **hormone imbalances** or elevated prolactin levels. *Craniopharyngioma* - Craniopharyngiomas are typically **suprasellar masses** that can cause visual disturbances and hormone deficiencies, but they often present in childhood or adolescence. - They are usually **cystic or partially calcified** and do not typically cause isolated **hyperprolactinemia**. *Metastatic lesion* - A metastatic lesion to the pituitary gland is possible, but it is much **less common** than a pituitary adenoma [2]. - While it could cause mass effect symptoms, a metastatic tumor is less likely to selectively produce **high prolactin levels** or present in this specific manner without a known primary cancer [2].

Practice by Chapter

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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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