Intern Report 1/27 – Hypercalcemia

Teaching Pearls:

  • Primary hyperparathyroidism and malignancy comprise of >90% of cases of hypercalcemia.
  • Primary hyperparathyroidism is the most common cause of hypercalcemia in outpatient settings.
    • Patients are often asymptomatic and/or have a history of kidney stones
  • Malignancy is the most common cause of hypercalcemia in inpatient admissions.
    • Labs often display severe hypercalcemia
    • Patients with severe hypercalcemia are often volume depleted as hypercalcemia can lead to nephrogenic diabetes insipidus
  • Initial Workup – First measure the PTH level
    • High PTH: diagnosis is likely primary hyperparathyroidism
    • High normal to mild elevation: think of primary hyperparathyroidism or Familial hypocalciuric hypercalcemia (FHH)
    • Low PTH: proceed onto further tests
  • Other work-up labs include PTHrP and vitamin D metabolites. Other considerations include SPEP/UPEP, TSH, Vitamin A, etc.
  • FHH differs from primary hyperparathyroidism in that the fractional excretion of Ca in FHH is low, whereas primary hyperparathyroidism is high.
    • Decreased fractional excretion of Calcium leads to lack of nephrolithiasis development.
  • Primary hyperparathyroidism has three different pathologic conditions:
    • Adenoma – 89-90%
    • Hyperplasia – 6.8%
    • Carcinoma – 1.2%
  • Should consider parathyroid carcinoma in patients with primary hyperparathyroidism and the following:
    • Severe elevations in calcium
    • Severe elevations in PTH
  • Management
    • IV fluids NS at 200-300cc/hour to maintain UO at 100-150cc/hour.
      • Loop diuretics only used in the setting of fluid overload
    • Calcitonin – onset of action: hours
      • Concern for tachyphylaxis
    • Bisphosphonates (pamidronate or zolendronate)
      • Onset of action >2 days

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