MCQ – 43177

Most common cause of hypercalcemic crisis is –

A.	Parathyroid adenoma
B.	Parathyroid hyperplasia
C.	Carcinoma breast
D.	Paget’s disease

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Correct Answer » A Explanation

A hypercalcemic crisis is a life-threatening medical emergency characterized by:

• Severe hypercalcemia (usually serum calcium >14 mg/dL)
• Dehydration
• Altered sensorium
• Cardiac arrhythmias
• Acute kidney injury

The two major causes are:

1. Primary hyperparathyroidism
2. Malignancy-associated hypercalcemia

Why Option A is Correct

Parathyroid adenoma is the most common cause of primary hyperparathyroidism, accounting for approximately 80–85% of cases.

Primary hyperparathyroidism is the most common cause of hypercalcemic crisis in surgical and endocrine MCQs.

Mechanism:

• Excess Parathyroid Hormone (PTH)
• Increased bone resorption
• Increased renal calcium reabsorption
• Increased intestinal calcium absorption (via Vitamin D activation)

Why Other Options are Incorrect

B. Parathyroid Hyperplasia

• Causes primary hyperparathyroidism.
• Accounts for approximately 10–15% of cases.
• Less common than parathyroid adenoma.

C. Carcinoma of the Breast

• Can cause hypercalcemia through:
  • Osteolytic bone metastases
  • PTH-related peptide (PTHrP)
• Malignancy is a common cause of severe hypercalcemia, but among the options, parathyroid adenoma remains the most common cause of hypercalcemic crisis in standard surgical/endocrine examinations.

D. Paget’s Disease

• Usually does not cause significant hypercalcemia.
• Hypercalcemia may rarely occur during prolonged immobilization.