Endocrinology — MCQs

A patient presented to OPD with complaints of fatigue, loss of appetite, constipation, urinary symptoms of kidney stone, and increased urination. The patient has a history of psychiatric disorder; you suspect a case of hyperparathyroidism. Which of the following investigations is useful in this condition?

Q1297

A 49-year-old male presents with recurrent episodes of watery diarrhoea, dehydration, hypokalemia, and achlorhydria. Which of the following neuroendocrine tumours can be responsible for these symptoms?

Q1298

What is the most common cause of Cushing's disease in a 60-year-old male?

Q1299

Which of the following is the most common cause of mortality in diabetic ketoacidosis?

Q1300

A patient presents with complaints of sudden onset headache, palpitation, and profuse sweating. The patient has had multiple similar episodes in the past. During these episodes, the patient's blood pressure is elevated. A 24-hour urinary metanephrine is elevated. What is the most likely diagnosis?

Endocrinology Indian Medical PG Practice Questions and MCQs

Question 1291: A 23-year-old female visited the clinician with a solitary thyroid nodule and was advised for thyroid function tests where TSH level is 27.3 mU/L, T3 is 1.24 ng/mL, and T4 is 4.87 μg/dL. Which of the following manifestations is true regarding the condition?

A. Weight gain (Correct Answer)
B. Diarrhea
C. Tachycardia
D. Heat intolerance

Explanation: ***Weight gain***- The patient's thyroid function tests (TFTs), showing a **highly elevated TSH** (27.3 mU/L) and **low T4** (4.87 μg/dL), confirm a diagnosis of **Primary Hypothyroidism** [1].- Weight gain is a classic symptom of hypothyroidism, resulting from reduced **basal metabolic rate** and frequently accompanied by **fluid retention** leading to *myxedema* [2]. *Heat intolerance*- Heat intolerance is a characteristic feature of **Hyperthyroidism**, where excess thyroid hormone increases heat production.- Patients with hypothyroidism typically experience **cold intolerance** due to decreased thermogenesis [2]. *Tachycardia*- **Tachycardia** (increased heart rate) is a common cardiovascular manifestation of **Hyperthyroidism** due to enhanced adrenergic effects [2].- Hypothyroidism generally leads to **bradycardia** (slow heart rate) and reduced cardiac contractility [2]. *Diarrhea*- Diarrhea is associated with **Hyperthyroidism** because of increased gastrointestinal motility.- Patients suffering from hypothyroidism commonly present with decreased bowel motility, leading to **constipation** [2].

Question 1292: A patient with a history of Graves' disease underwent I-131 ablation therapy. Which of the following is the most likely long-term side effect of this treatment?

A. Hypothyroidism (Correct Answer)
B. Thyroid Storm
C. Hyperthyroidism
D. Acute Thyroiditis

Explanation: ***Hypothyroidism*** - The primary mechanism of **I-131 ablation** is the destruction of functional thyroid tissue by radiation, leading to a permanent reduction in hormone production. - **Hypothyroidism** is the most common and often inevitable long-term complication following successful **radioiodine ablation** for conditions like Graves' disease or thyroid cancer, occurring in 80-90% of patients within the first year [1]. - Requires lifelong thyroid hormone replacement therapy. *Acute Thyroiditis* - This is a possible immediate side effect, known as **radiation thyroiditis**, causing transient local pain and tenderness within days to weeks of treatment. - It is a short-term inflammatory response due to radiation-induced thyroid cell damage, not the defining long-term side effect [1]. - Usually self-limiting and managed with NSAIDs or corticosteroids. *Hyperthyroidism* - Although an initial transient surge of thyroid hormones (due to tissue destruction releasing stored hormone) can occur within the first 1-2 weeks after I-131, this is temporary [2]. - The treatment's primary purpose is to permanently cure hyperthyroidism by destroying thyroid tissue. - Persistent or recurrent hyperthyroidism would indicate treatment failure, not a side effect. *Thyroid Storm* - A **thyroid storm** is an acute, life-threatening exacerbation of hyperthyroidism usually precipitated by factors like infection, surgery, or trauma [2]. - While extremely rare, radioiodine therapy can theoretically precipitate a storm in inadequately prepared, severely hyperthyroid patients [2]. - This is **not a likely or common side effect** compared to permanent hypothyroidism, and proper pre-treatment with antithyroid drugs minimizes this risk.

Question 1293: What is the primary mechanism behind tissue damage in long-standing diabetes?

A. Insulin resistance
B. Sorbitol accumulation
C. Decreased insulin secretion
D. Hyperglycemia (Correct Answer)

Explanation: ***Hyperglycemia*** - Chronic exposure to high glucose levels is the fundamental upstream trigger initiating all harmful biochemical pathways that lead to **microvascular** and **macrovascular** complications [4]. - It directly leads to the formation of **Advanced Glycation End products (AGEs)**, activation of the **protein kinase C** pathway, and increased **oxidative stress**, all contributing to irreversible tissue damage. *Insulin resistance* - This is a key defect in **Type 2 Diabetes** [4] that *causes* hyperglycemia, but the resulting high glucose level is the direct downstream mechanism causing structural organ damage. - Its primary immediate effect is impaired glucose uptake and utilization in peripheral tissues [1], rather than the intrinsic structural damage seen in **vascular endothelium** or nerves. *Sorbitol accumulation* - This is a specific downstream consequence of chronic **hyperglycemia** activating the **polyol pathway**; therefore, it is a mechanism of damage, not the primary inciting cause. - Accumulation of **sorbitol** and resultant depletion of **NADPH** primarily contributes to osmotic stress and oxidative damage in specific cells like pericytes and Schwann cells (neuropathy). *Decreased insulin secretion* - This is the core pathophysiological defect in **Type 1 Diabetes** and a feature of advanced Type 2 Diabetes (**beta-cell failure**) that *results* in hyperglycemia [3]. - The lack of insulin elevates blood glucose, making **hyperglycemia** the direct variable driving the damaging biochemical process in target tissues over time [2].

Question 1294: A hypertensive patient’s lab results reveal hypernatremia, hypokalemia, and metabolic alkalosis. What is the most probable diagnosis?

A. Conn's Syndrome (Correct Answer)
B. Addison’s Disease
C. Cushing's Disease
D. Diabetes Insipidus

Explanation: ***Conn's Syndrome***- This condition, known as primary **hyperaldosteronism**, is defined by autonomous overproduction of aldosterone, leading to volume expansion and **hypertension** [1].- Aldosterone acts on the principal cells of the collecting duct to increase Na+ reabsorption (causing hypernatremia) while simultaneously promoting K+ and H+ excretion (causing **hypokalemia** and **metabolic alkalosis**) [2].*Addison’s Disease*- Addison’s disease is primary adrenal insufficiency, characterized by deficiency of mineralocorticoids and glucocorticoids [3].- This lack of aldosterone leads to impaired Na+ reabsorption and deficient K+ excretion, resulting in **hyponatremia** and **hyperkalemia** (the opposite of the clinical picture).*Diabetes Insipidus*- Diabetes Insipidus (DI) is a disorder of insufficient ADH action, resulting in polyuria and profound free water loss leading to **hypernatremia**.- DI does not arise from mineralocorticoid dysfunction, thus it would not typically cause **hypokalemia** or metabolic alkalosis.*Cushing's Disease*- Cushing's disease involves excess **cortisol** (a glucocorticoid), which can cause hypertension and occasionally hypokalemia.- However, the combination of **hypernatremia**, significant **hypokalemia**, and severe **metabolic alkalosis** strongly points toward primary **mineralocorticoid excess** rather than glucocorticoid excess [1].

Question 1295: What is the most common cause of death in children with Diabetic ketoacidosis?

A. Hypokalemia
B. Cerebral edema (Correct Answer)
C. Dehydration
D. Sepsis

Explanation: ***Cerebral edema*** - It is the **most common cause of mortality** in pediatric DKA, occurring in 0.5-1% of cases with a mortality rate of 20-25% [1] - Occurs due to rapid changes in **plasma osmolality** during treatment - the rapid decrease of blood glucose and effective osmolarity creates an osmotic gradient, causing fluid shifts into brain cells - Leads to potentially fatal **intracranial pressure** elevation with clinical features of headache, altered mental status, bradycardia, and respiratory depression - Risk factors include: new-onset diabetes, younger age, severe acidosis, and rapid fluid administration *Hypokalemia* - Potassium levels often drop dramatically during DKA treatment as insulin drives potassium into cells, potentially causing life-threatening **cardiac arrhythmias** [1] - This complication is highly anticipated and routinely managed by **potassium replacement therapy** with close monitoring [3] - While potentially fatal if unrecognized, it is a **preventable and treatable** condition with proper electrolyte management *Dehydration* - Severe dehydration causing **hypovolemic shock** is a major factor contributing to morbidity in DKA [2] - Effectively managed by aggressive **IV fluid resuscitation** with careful monitoring [3] - In treated pediatric DKA, the failure leading to death is typically the development of **cerebral edema** rather than persistent volume depletion [1] *Sepsis* - While sepsis can precipitate DKA, it is an underlying **trigger** or precipitating factor, not the direct physiological cause of death during DKA itself - The overwhelming fatality **in** pediatric DKA (as opposed to from the precipitating illness) is generally attributed to **cerebral edema** from rapid fluid shifts leading to central nervous system complications [1]

Question 1296: A patient presented to OPD with complaints of fatigue, loss of appetite, constipation, urinary symptoms of kidney stone, and increased urination. The patient has a history of psychiatric disorder; you suspect a case of hyperparathyroidism. Which of the following investigations is useful in this condition?

A. Sestamibi scan (Correct Answer)
B. USG neck
C. CT neck
D. PET scan

Explanation: ***Sestamibi scan*** - This is the standard **nuclear medicine study** used for localizing hyperfunctioning **parathyroid adenomas** prior to surgery (parathyroidectomy), essential for confirming the source of hypercalcemia [1]. - The scan is highly sensitive because the tracer (**Technetium-99m Sestamibi**) is retained longer in the hyperactive parathyroid tissue than in the surrounding thyroid tissue [1]. *USG neck* - **Ultrasonography** is an anatomical study that is often used as a basic initial imaging step due to its non-invasiveness, but it has lower overall sensitivity (50-80%) in localization. - It is poor at locating **ectopic or deep-seated adenomas** and cannot confirm if the lesion is truly hyperfunctioning, which is critical for diagnosis. *CT neck* - **Computed Tomography** is generally reserved for situations where non-invasive methods fail, especially when trying to localize **ectopic glands** deep in the **mediastinum** or neck. - It is not preferred as a first-line investigation due to the associated **radiation exposure** and lack of functional information regarding the glandular activity. *PET scan* - Standard **FDG-PET scans** are mostly ineffective for localizing benign parathyroid adenomas because they rarely exhibit the high metabolic activity required for tracer uptake. - Specialized PET tracers, such as **11C-methionine**, may be used in complicated cases of persistent or recurrent hyperparathyroidism, but are not routine for initial diagnosis. Note: The patient's presentation of kidney stones, psychiatric symptoms, and polyuria is consistent with primary hyperparathyroidism secondary to hypercalcemia [2, 3].

Question 1297: A 49-year-old male presents with recurrent episodes of watery diarrhoea, dehydration, hypokalemia, and achlorhydria. Which of the following neuroendocrine tumours can be responsible for these symptoms?

A. Glucagonoma
B. VIPoma (Correct Answer)
C. Insulinoma
D. Somatostatinoma

Explanation: A 49-year-old male presents with recurrent episodes of watery diarrhoea, dehydration, hypokalemia, and achlorhydria. Which of the following neuroendocrine tumours can be responsible for these symptoms? ***VIPoma***- The constellation of symptoms—watery diarrhoea, dehydration, hypokalemia, and achlorhydria—is known as **WDHA syndrome** (Watery Diarrhea, Hypokalemia, Achlorhydria), which is pathognomonic for a VIP-secreting tumour. [1] - **Vasoactive Intestinal Peptide (VIP)** acts as an intestinal secretagogue, leading to massive secretion of water and electrolytes, causing profound secretory diarrhea and subsequent life-threatening **hypokalemia** and dehydration. [1] *Insulinoma* - This tumour hypersecretes **insulin**, leading to severe symptoms of **hypoglycemia** (neuroglycopenic symptoms) which are typically worse in the fasting state. [2] - Insulinoma does not cause secretory diarrhea, hypokalemia, or achlorhydria. [2] *Somatostatinoma* - This tumor typically presents with the classic triad of **diabetes mellitus**, **gallstones (cholelithiasis)**, and **steatorrhea** (due to inhibition of pancreatic enzyme secretion). - While diarrhea can occur due to malabsorption, the overwhelming secretory diarrhea and achlorhydria defining this case are not characteristic. *Glucagonoma* - The primary clinical manifestations of glucagonoma include **necrolytic migratory erythema** (a distinctive skin rash), mild **diabetes mellitus**, and often **weight loss**. - It does not cause massive watery diarrhea leading to hypokalemia and achlorhydria.

Question 1298: What is the most common cause of Cushing's disease in a 60-year-old male?

A. Small-cell lung cancer
B. Adrenal tumor
C. Pituitary microadenoma (Correct Answer)
D. Ectopic ACTH syndrome

Explanation: ***Pituitary microadenoma*** - Cushing's **Disease** is specifically defined as hypercortisolism caused by an ACTH-secreting tumor of the pituitary gland, which is typically a **microadenoma** (<10 mm) [2]. - Pituitary adenomas are the most common cause of **endogenous** ACTH-dependent hypercortisolism (Cushing's Disease), regardless of the patient's age or sex [1]. *Small-cell lung cancer* - This is the most common cause of **ectopic ACTH syndrome**, which is a form of Cushing's **Syndrome**, not Cushing's Disease [1]. - Ectopic secretion generally leads to rapidly progressive, severe hypercortisolism and is often associated with hypokalemic metabolic alkalosis. *Adrenal tumor* - Adrenal tumors (adenomas or carcinomas) cause **ACTH-independent** Cushing's syndrome by directly overproducing cortisol [1]. - In this etiology, the pituitary gland is suppressed, resulting in very low or undetectable plasma **ACTH levels** [3]. *Ectopic ACTH syndrome* - While ectopic ACTH syndrome (often from bronchial carcinoids or small-cell lung cancer) is a significant cause of Cushing's **Syndrome** in elderly males, it is not the definition of Cushing's **Disease**. [1] - Ectopic sources produce ACTH unresponsive to **high-dose dexamethasone suppression** tests, unlike most cases of Cushing's Disease.

Question 1299: Which of the following is the most common cause of mortality in diabetic ketoacidosis?

A. Cardiac arrhythmia
B. Cerebral edema (Correct Answer)
C. Acute kidney injury
D. Acute respiratory distress syndrome

Explanation: ***Cerebral edema*** - This is the most catastrophic and frequent cause of death, particularly in children and adolescents being treated for DKA [2].- It is often linked to the **rapid administration of hypotonic fluids** or overly quick correction of **hyperglycemia**, causing rapid shifts in **osmolality** that lead to brain swelling [3]. *Acute respiratory distress syndrome*- While DKA is a risk factor for ARDS (often secondary to severe systemic inflammation or associated **sepsis**), it is not the most common direct cause of death [2].- Focus remains on metabolic management; respiratory failure is less common than neurological compromise as a fatal event. *Cardiac arrhythmia*- Severe **hypokalemia** (often unmasked or worsened by insulin therapy) can precipitate fatal cardiac arrhythmias, such as **ventricular fibrillation** [2].- Though a serious complication, carefully monitored electrolyte management generally prevents this, making it less common than cerebral edema as the leading cause of mortality. *Acute kidney injury*- AKI is highly common in DKA, primarily driven by severe **volume depletion** and resulting **prerenal azotemia** [1].- This is reversible with fluid resuscitation and, while it increases overall morbidity, it rarely causes acute mortality more frequently than cerebral edema during the initial hospitalization phase.

Question 1300: A patient presents with complaints of sudden onset headache, palpitation, and profuse sweating. The patient has had multiple similar episodes in the past. During these episodes, the patient's blood pressure is elevated. A 24-hour urinary metanephrine is elevated. What is the most likely diagnosis?

A. Renal artery stenosis
B. Pheochromocytoma (Correct Answer)
C. Hyperthyroidism
D. Addison's disease

Explanation: ***Pheochromocytoma***- This clinical presentation—paroxysmal episodes of headache, palpitations, and profuse sweating (the classic triad)—coupled with elevated blood pressure strongly suggests a **pheochromocytoma** (a tumor of the adrenal medulla secreting catecholamines). - The definitive biochemical confirmation is the elevated 24-hour urinary **metanephrines** and normetanephrines, which are breakdown products of epinephrine and norepinephrine. *Addison's disease* - This condition involves primary adrenal *insufficiency* (hypocortisolism), which typically presents with **hypotension**, fatigue, weight loss, and **hyperpigmentation**, not hypertensive crises. - It involves decreased production of adrenal hormones, not the episodic overproduction of **catecholamines** seen here. *Renal artery stenosis* - This is a cause of secondary hypertension due to chronic activation of the **Renin-Angiotensin-Aldosterone System (RAAS)**, leading to persistent, non-paroxysmal elevation of blood pressure. - It would not cause the specific triad of episodic symptoms (headache, sweating, palpitations) or lead to elevated **urinary metanephrines**. *Hyperthyroidism* - While it can cause palpitations, tremor, and systolic hypertension, these symptoms are typically chronic and sustained, lacking the sudden paroxysmal nature described. - The primary biochemical abnormality involves elevated **T3/T4 hormones**, not the excessive urinary excretion of **metanephrines** as detailed in this case.

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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