A calcium above 14 mg/dL, or a symptomatic patient at any level, is an emergency. These patients are profoundly volume-depleted, because a high calcium causes a nephrogenic diabetes insipidus, and restoring the circulating volume alone will drop the calcium substantially.
The order of treatment
| # | Step | Detail |
|---|---|---|
| 1 | Rehydrate — this is the treatment | 0.9% sodium chloride, 200–300 mL/h initially, titrated to a urine output of 100–150 mL/h. Reassess hourly for fluid overload in the elderly and in cardiac or renal disease. |
| 2 | Stop what is making it worse | Thiazides, lithium, calcium and vitamin D supplements, antacids. Mobilise the patient. Review digoxin — hypercalcaemia potentiates digoxin toxicity. |
| 3 | Turn off the osteoclast | Only once the patient is volume-replete. Zoledronic acid 4 mg intravenously, dose-adjusted in renal impairment — it acts in 2–4 days and lasts weeks. Add calcitonin for the first 24–48 hours if the calcium must fall today; denosumab if that fails. |
| 4 | Treat the cause | Steroids for lymphoma, myeloma and granulomatous disease. In refractory disease with renal or cardiac failure, consider dialysis. |
Do not reach for furosemide
A loop diuretic given to a dehydrated hypercalcaemic patient makes them more dehydrated and the calcium higher. It has one role only: managing fluid overload in a patient who has already been fully rehydrated. Fluids first, and only then, if the lungs demand it, a diuretic.
Recognising it
The symptoms track the speed of the rise as much as the height of it. Drowsiness, confusion, vomiting, polyuria and thirst, profound weakness, and in severe cases coma. The patient is dry: dry mucosae, tachycardia, a postural drop. The ECG shows a short QT interval, and in severe cases a bradyarrhythmia.
While you are resuscitating, ask why
A calcium this high with a suppressed PTH is malignancy until proved otherwise — PTHrP from a squamous, renal or breast primary, osteolytic metastases, myeloma, or calcitriol from a lymphoma. A calcium this high with a raised PTH and a palpable neck mass raises parathyroid carcinoma. Send the PTH with the first set of bloods, before the fluids dilute the picture and before anyone asks you what it was.