UMEM Educational Pearls

Title: Hypercalcemia of Malignancy

Keywords: Oncology, Endocrine, Hypercalcemia, Electrolyte (PubMed Search)

Posted: 8/26/2024 by Sarah Dubbs, MD (Updated: 8/31/2024)
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We see patients with nausea, fatigue, altered mental status, and other vague symptoms all day, every day in the ED. Let's not forget about hypercalcemia in the differential, especially in patients with a known malignancy! Many tumor types secrete a Parathyroid hormone (PTH)- related protein that mimics PTH and leads to high calcium levels.

Here are some clinical pearls on hypercalcemia of malignancy:

Total serum calcium does not correlate accurately with the physiologically active free form of calcium. If you are concerned, obtain an ionized calcium level OR calculate based on albumin: Corrected Calcium = (0.8 * (Normal Albumin - Pt's Albumin)) + Serum Ca
ECG findings of hypercalcemia can include:
- Shortened QT interval
- ST elevation
- Osborne waves (positive deflection at the end of the QRS)
- Bradydysrhythmia
The degree of elevation correlates with the degree of symptoms (ionized calcium):
- Mild: Total Ca 10.5-11.9 mg/dL (2.5-3 mmol/L) or Ionized Ca 5.6-8 mg/dL (1.4-2 mmol/L)
- Moderate: Total Ca 12-13.9 mg/dL (3-3.5 mmol/L) or Ionized Ca 8-10 mg/dL (2-2.5 mmol/L)
- Severe, aka Hypercalcemic crisis: Total Ca 14-16 mg/dL (3.5-4 mmol/L) or Ionized Ca 10-12 mg/dL (2.5-3 mmol/L)
IV fluids are the mainstay of initial treatment. Some patients may benefit from bisphosphonates after fluids, with the consultation of oncology and endocrine. Hemodialysis can be considered for patients with cardiac dysrhythmias or severe neurologic symptoms, or if large volumes of fluids cannot be tolerated.

References

Walker MD, Shane E. Hypercalcemia: A Review. JAMA. 2022 Oct 25;328(16):1624-1636. doi: 10.1001/jama.2022.18331. PMID: 36282253.

Hu MI. Hypercalcemia of Malignancy. Endocrinol Metab Clin North Am. 2021 Dec;50(4):721-728. doi: 10.1016/j.ecl.2021.07.003. PMID: 34774243.