Hypercalcemia

Question 1

Causes of Hypercalcemia

Answer 1

BONE RESORPTION

• Primary hyperparathyroidism
• Secondary and tertiary hyperparathyroidism
• Malignancy
• Thyrotoxicosis
• Other

CALCIUM ABSORPTION

• Increased calcium intake
  
  • Chronic kidney disease
  • Milk alkali syndrome
• Hypervitaminosis D

MISCELLANEOUS CAUSES

• Lithium
• Thiazide diuretics
• Pheochromocytoma
• Adrenal insufficiency
• Rhabdomyolysis and acute renal failure
• Theophylline toxicity
• Familial hypocalciuric hypercalcemia
• Metaphyseal chondrodysplasia
• Congenital lactase deficiency

Question 2

Primary hyperparathyroidism

Answer 2

Hypercalcemia in primary hyperparathyroidism is due to parathyroid hormone-mediated activation of osteoclasts leading to increased bone resorption. In addition, intestinal calcium absorption is elevated.

Patients typically have only small elevations in serum calcium concentrations (less than 11 mg/dL or 2.75 mmol/L), and many have mostly high-normal values with intermittent hypercalcemia

These “normal” values in the presence of hypercalcemia are inappropriately high