Endocrinology — MCQs

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 1501: A 45-year-old woman presents with fatigue and muscle weakness. Blood tests reveal hypercalcemia. What is the most likely cause of her symptoms?

A. Increased parathyroid hormone secretion (Correct Answer)
B. Decreased bone resorption
C. Increased calcitonin secretion
D. Decreased renal calcium reabsorption

Explanation: ***Increased parathyroid hormone secretion*** - **Primary hyperparathyroidism** is a common cause of hypercalcemia, often presenting with fatigue and muscle weakness due to the effects of high calcium levels [2], [3]. - **Parathyroid hormone (PTH)** directly increases serum calcium by promoting bone resorption, renal calcium reabsorption, and intestinal calcium absorption (indirectly via vitamin D activation) [1]. *Decreased bone resorption* - **Decreased bone resorption** would lead to lower serum calcium levels, as less calcium would be mobilized from bones into the bloodstream. - This option contradicts the clinical finding of **hypercalcemia**. *Increased calcitonin secretion* - **Calcitonin** lowers serum calcium by inhibiting bone resorption and increasing renal calcium excretion. - An increase in calcitonin would therefore cause **hypocalcemia**, not hypercalcemia. *Decreased renal calcium reabsorption* - **Decreased renal calcium reabsorption** would result in increased urinary calcium excretion and thus contribute to **hypocalcemia**, counteracting the observed hypercalcemia. - This mechanism is the opposite of what occurs in primary hyperparathyroidism, where PTH increases renal calcium reabsorption [1].

Question 1502: A 30-year-old man complains of severe recurrent headaches and has been found to have elevated blood pressure. What diagnostic test is essential to evaluate the underlying cause?

A. Brain MRI for structural brain issues
B. Thyroid function tests for thyroid disorders
C. Electroencephalogram (EEG) for seizure disorders
D. 24-hour urine test to evaluate for pheochromocytoma (Correct Answer)

Explanation: 24-hour urine test to evaluate for pheochromocytoma - The combination of **recurrent severe headaches** and **elevated blood pressure** in a young adult is highly suspicious for a **pheochromocytoma**, a tumor of the adrenal medulla that secretes catecholamines. - A **24-hour urine test** for metanephrines and normetanephrines is the gold standard for diagnosing pheochromocytoma by measuring catecholamine metabolites. *Brain MRI for structural brain issues* - While headaches can be caused by structural brain issues, **elevated blood pressure** is not a primary symptom suggesting a brain tumor or other structural pathology as the direct cause of the hypertension [1]. - An MRI would be more relevant if there were focal neurological deficits, vision changes, or other red flags for intracranial pathology [1]. *Thyroid function tests for thyroid disorders* - **Hyperthyroidism** can cause hypertension, but it typically presents with other symptoms like weight loss, palpitations, tremor, and heat intolerance, which are not mentioned in this case. - While a general workup for hypertension might include thyroid function, it's not the essential test for the specific combination of severe headaches and hypertension in this context, especially given the paroxysmal nature implied by "recurrent severe headaches" [2]. *Electroencephalogram (EEG) for seizure disorders* - **Seizure disorders** are characterized by altered consciousness, convulsions, or other episodic neurological events, which are not described. - An EEG assesses brain electrical activity and would not be the initial or essential diagnostic test for evaluating the cause of recurrent headaches paired with elevated blood pressure.

Question 1503: A 35-year-old man presents with fatigue and salt craving. His laboratory results show low cortisol and aldosterone levels. Which condition is he most likely to have?

A. Cushing's syndrome
B. Addison's disease (Correct Answer)
C. Hyperthyroidism
D. Pheochromocytoma

Explanation: ***Addison's disease*** - **Addison's disease** (primary adrenal insufficiency) is characterized by the destruction of the adrenal cortex, leading to **low cortisol and aldosterone levels** [1]. - Symptoms like **fatigue** and **salt craving** are classic manifestations due to mineralocorticoid deficiency (aldosterone) leading to sodium loss [1], [2]. *Cushing's syndrome* - **Cushing's syndrome** is caused by **excess cortisol**, leading to symptoms like central obesity, moon facies, and muscle weakness, which are opposite to the symptoms presented. - Aldosterone levels are typically normal or elevated, not low, unless there's a co-existing adrenal issue. *Hyperthyroidism* - **Hyperthyroidism** involves overproduction of **thyroid hormones**, leading to symptoms such as weight loss, heat intolerance, and palpitations. - It does not directly affect cortisol or aldosterone levels, nor does it typically cause salt craving. *Pheochromocytoma* - **Pheochromocytoma** is a tumor of the adrenal medulla that secretes **excess catecholamines** (epinephrine and norepinephrine). - This leads to symptoms such as hypertension, palpitations, and headaches, and does not directly cause low cortisol or aldosterone.

Question 1504: A 45-year-old man presents with a neck mass and elevated serum calcium levels. A biopsy of the mass shows sheets of chief cells. What is the most likely diagnosis?

A. Papillary carcinoma
B. Follicular carcinoma
C. Parathyroid adenoma (Correct Answer)
D. Anaplastic carcinoma

Explanation: ***Parathyroid adenoma*** - The presence of **elevated serum calcium levels** along with **sheets of chief cells** in the biopsy is typical for parathyroid adenoma, which is responsible for primary hyperparathyroidism. - It commonly presents as a **mass in the neck** or jaw due to its location in the parathyroid glands, which aligns with the patient's symptoms. *Anaplastic carcinoma* - This is a highly aggressive cancer that would typically present with **rapid growth** and potential invasion, rather than benign appearing **chief cells**. - It is not associated with **elevated serum calcium** as a primary feature. *Follicular carcinoma* - Follicular carcinoma primarily arises from thyroid follicular cells and usually presents with **thyroid nodules**, not chief cells associated with calcium metabolism. - It typically does not result in significant **elevated serum calcium levels**, as it is more related to thyroid hormone production. *Papillary carcinoma* - This carcinoma usually presents with **nuclear features** such as **nuclear grooves** and is not associated with chief cells or **hypercalcemia**. - It primarily affects the thyroid gland and leads to **thyroid dysfunction**, rather than calcium regulation issues.

Question 1505: In a patient diagnosed with hyperaldosteronism, which electrolyte imbalance is most commonly observed?

A. Hypernatremia
B. Hyponatremia
C. Hyperkalemia
D. Hypokalemia (Correct Answer)

Explanation: Detailed explanation of electrolyte imbalance in hyperaldosteronism below: ***Hypokalemia*** - In **hyperaldosteronism**, excessive **aldosterone** secretion leads to increased sodium reabsorption and **potassium excretion** in the renal tubules [1]. - This persistent loss of potassium through the urine results in **low serum potassium levels**, causing **hypokalemia** [2]. *Hypernatremia* - While aldosterone increases **sodium reabsorption**, the body's **compensatory mechanisms**, such as increased water intake and natriuresis from pressure, usually prevent significant **hypernatremia** [3]. - Significant hypernatremia is **not the most common** electrolyte imbalance observed in primary hyperaldosteronism. *Hyponatremia* - **Hyponatremia** is not directly caused by hyperaldosteronism; in fact, increased sodium reabsorption would tend to oppose it. - It suggests **fluid overload** or other diseases, not typical of hyperaldosteronism. *Hyperkalemia* - **Hyperkalemia** is the opposite of what occurs in hyperaldosteronism, as aldosterone's primary role in electrolyte balance includes promoting **potassium excretion** [1]. - Therefore, **excessive aldosterone** activity leads to **hypokalemia**, not hyperkalemia [2].

Question 1506: A 15-year-old with a history of type 1 diabetes presents with confusion, headache, and palpitations. Blood glucose is 55 mg/dL. After administering oral glucose, what is the most important next step in managing this patient?

A. Reassess blood glucose in 15 minutes (Correct Answer)
B. Administer intravenous glucose immediately
C. Perform a continuous glucose monitoring system placement
D. Adjust the insulin pump settings immediately

Explanation: ***Reassess blood glucose in 15 minutes*** - Following initial treatment with oral glucose for **hypoglycemia**, it is crucial to recheck the blood glucose level to confirm that it has risen to a safe range and to prevent a recurrence of symptoms [1]. - This step allows for a determination of whether further intervention is needed or if the initial treatment was sufficient. *Administer intravenous glucose immediately* - **Intravenous glucose** is typically reserved for severe hypoglycemia in patients who are unconscious, unable to swallow, or when oral glucose is ineffective. - Since the patient was able to take oral glucose, this immediate aggressive measure is generally not the first next step. *Perform a continuous glucose monitoring system placement* - While **continuous glucose monitoring (CGM)** is valuable for long-term management and trend analysis in diabetes, it is not an immediate treatment or assessment tool for an acute hypoglycemic episode. - Placement and calibration of a CGM system take time and do not address the immediate need to confirm glucose normalization. *Adjust the insulin pump settings immediately* - Adjusting **insulin pump settings** is part of preventing future hypoglycemic events, but it is not the most immediate next step after initial treatment for an acute episode. - The priority is to ensure the current hypoglycemic event is resolved before addressing long-term management changes.

Question 1507: A 48-year-old woman with a history of thyroidectomy presents with muscle cramps and perioral tingling. Her serum calcium level is 7.2 mg/dL. What is the most likely diagnosis?

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

Explanation: The patient's symptoms of **muscle cramps** and **perioral tingling** are classic manifestations of **hypocalcemia** [1]. A **serum calcium level of 7.2 mg/dL** (normal range 8.5-10.2 mg/dL) confirms a low calcium concentration. Post-thyroidectomy, accidental removal or damage to the **parathyroid glands** is a common cause of hypocalcemia [1]. *Hypercalcemia* - **Hypercalcemia** would present with symptoms such as **constipation, polyuria, polydipsia, fatigue**, and **confusion**, which are opposite to the patient's presentation. - The patient's calcium level is significantly low (7.2 mg/dL), directly contradicting a diagnosis of hypercalcemia. *Hypokalemia* - **Hypokalemia** (low potassium) can cause muscle weakness and cramps, but typically does not cause **perioral tingling**. - No information is provided about the patient's potassium levels, and the primary issue is clearly related to calcium. *Hyponatremia* - **Hyponatremia** (low sodium) can cause symptoms like nausea, confusion, headache, and in severe cases, seizures, but not typically **perioral tingling** or generalized muscle cramps as the primary complaint. - The provided information specifically points to a calcium imbalance, not a sodium imbalance.

Question 1508: A teenager with type 1 diabetes experiences fluctuating blood glucose levels despite adhering to prescribed insulin therapy. What intervention could best help stabilize her glycemic control?

A. Switch to a different type of insulin
B. Introduce a continuous glucose monitoring system (Correct Answer)
C. Increase carbohydrate intake at each meal
D. Reduce physical activity

Explanation: A **continuous glucose monitoring (CGM) system** provides real-time glucose readings, allowing for immediate adjustments to insulin doses and dietary intake in response to fluctuations [1]. This continuous feedback helps identify patterns of **hypoglycemia** and **hyperglycemia** that might be missed with periodic finger-prick tests, leading to better overall glycemic control [1]. While insulin regimens can be optimized, simply switching to a different type of insulin might not address the underlying issue of **fluctuating glucose levels** if the timing and dosing are still based on infrequent measurements [1]. Increasing **carbohydrate intake** without adjusting insulin doses appropriately would likely exacerbate the problem, leading to higher post-meal glucose spikes and further instability [2]. Regular physical activity is beneficial for overall health, and its impact on glucose levels can be managed through appropriate insulin adjustments and carbohydrate intake [1].

Question 1509: A patient presents with hyperglycemia and ketosis without significant acidosis. What is the most likely diagnosis?

A. Diabetic ketoacidosis; start IV fluids and insulin
B. Lactic acidosis; administer IV fluids and sodium bicarbonate
C. Severe hypoglycemia; provide IV glucose
D. Hyperosmolar hyperglycemic state; initiate IV fluids and insulin (Correct Answer)

Explanation: Hyperosmolar hyperglycemic state; initiate IV fluids and insulin - **Hyperosmolar hyperglycemic state (HHS)** is characterized by **severe hyperglycemia**, often exceeding 600 mg/dL, leading to **profound dehydration** and elevated serum osmolality [1]. - While hyperglycemia and sometimes mild ketosis may be present, **significant acidosis is typically absent**, differentiating it from DKA. Initial management focuses on aggressive intravenous fluid resuscitation and cautious insulin administration [1]. Diabetic ketoacidosis; start IV fluids and insulin - **Diabetic ketoacidosis (DKA)** involves **hyperglycemia, ketosis, and metabolic acidosis** (pH <7.3 and bicarbonate <18 mEq/L), which is not fully consistent with the patient's presentation of "without significant acidosis" [2]. - While treatment includes IV fluids and insulin, the **lack of significant acidosis** makes DKA less likely as the primary diagnosis [2]. Lactic acidosis; administer IV fluids and sodium bicarbonate - **Lactic acidosis** is characterized by **elevated lactate levels** and **metabolic acidosis**, irrespective of ketosis, which is not described. - The patient's presentation includes **hyperglycemia and ketosis**, which are not typical features of primary lactic acidosis. Severe hypoglycemia; provide IV glucose - **Severe hypoglycemia** is defined by **low blood glucose levels** (typically <70 mg/dL or with symptoms requiring assistance), which contradicts the patient's presentation of **hyperglycemia** [1]. - Treatment with IV glucose would be appropriate for hypoglycemia, but the diagnostic criteria are not met.

Question 1510: A 50-year-old male with poorly controlled diabetes presents with severe dehydration, metabolic acidosis, hyperglycemia, and ketonemia. What processes are likely occurring?

A. Lactic acidosis with increased renal ammonium production
B. Glucose-induced hyperkalemia with enhanced gluconeogenesis
C. Hyperosmolar hyperglycemic state with decreased insulin sensitivity
D. Diabetic ketoacidosis with ketoacid production (Correct Answer)

Explanation: ### Diabetic ketoacidosis with ketoacid production - The combination of **poorly controlled diabetes**, **severe dehydration**, **metabolic acidosis**, **hyperglycemia**, and **ketonemia** is pathognomonic for **diabetic ketoacidosis (DKA)** [1]. - In DKA, **insulin deficiency** leads to unchecked lipolysis, resulting in the production of **ketone bodies** (acetoacetate, beta-hydroxybutyrate, and acetone), which are strong acids, causing **metabolic acidosis** [2], [3]. ### Lactic acidosis with increased renal ammonium production - While metabolic acidosis is present, **lactic acidosis** would be characterized by elevated **lactate levels** and typically occurs in states of tissue hypoperfusion or hypoxia, which is not primarily indicated here. - **Increased renal ammonium production** is a compensatory mechanism for chronic metabolic acidosis, but it doesn't describe the primary pathological process. ### Glucose-induced hyperkalemia with enhanced gluconeogenesis - **Hyperkalemia** can occur in DKA due to acidosis and insulin deficiency, as H+ ions drive K+ out of cells while lack of insulin prevents K+ entry [2], [4]. However, "glucose-induced" hyperkalemia is not an accurate descriptor of the primary mechanism. - **Enhanced gluconeogenesis** does occur in DKA due to insulin deficiency and counter-regulatory hormones, but it's not the central process explaining the full clinical picture. ### Hyperosmolar hyperglycemic state with decreased insulin sensitivity - **Hyperosmolar hyperglycemic state (HHS)** also involves severe hyperglycemia and dehydration, but it is characterized by **minimal or no ketosis/acidosis**, distinguishing it from DKA [2]. - **Decreased insulin sensitivity** is a feature of type 2 diabetes and contributes to hyperglycemia in both DKA and HHS, but it doesn't explain the significant ketonemia and acidosis seen here.

Practice by Chapter

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