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Hypercalcaemia

Lab results

Use adjusted calcium. Symptomatic or adjusted Ca²⁺ ≥3.0 mmol/L needs urgent treatment; ≥3.5 is severe.

Act now

  1. 1

    IV 0.9% sodium chloride rehydration guided by fluid status and cardiac/renal function.

  2. 2

    Stop thiazides, calcium and vitamin D supplements.

Assess

  • Symptoms: thirst, polyuria, nausea, constipation, abdominal pain, confusion, drowsiness.
  • Fluid status, ECG (short QT, arrhythmia), drugs (thiazides, calcium/vitamin D supplements, lithium).
  • Likely cause: primary hyperparathyroidism or malignancy (around 90% between them).

Investigations

  • Adjusted calcium, PTH (key test — high or inappropriately normal suggests hyperparathyroidism), U&E, phosphate, magnesium, ALP, vitamin D, myeloma screen, CXR; malignancy work-up if PTH suppressed.

Manage

  • If calcium remains high after rehydration: IV bisphosphonate (takes 2–4 days to work).
  • Loop diuretics only for fluid overload, not routinely.
  • Monitor U&E and calcium daily; fluid balance.

Escalate when

  • Severe hypercalcaemia, reduced consciousness, arrhythmia, or AKI: senior review; consider endocrinology, oncology or renal input (dialysis in refractory cases).

Doses and prescribing

Zoledronic acid

4 mg IV over 15 minutes, or pamidronate 30–90 mg (by severity) at 20 mg/hour.

Reduce dose or rate in renal impairment (check BNF/SPC); check dental history and renal function.

Bisphosphonates are licensed for hypercalcaemia of malignancy; non-malignant use is off-label.

Check the BNF and your local formulary before prescribing.

Written to current guidance · sources checked 14 Nov 2026. We watch NICE for updates weekly.

Sources (2)

Reviewed by Aboodee Alhasso, MPharm MRCPharm IP on 14 Nov 2026

Calculators for this

For healthcare professionals, as an aid to clinical judgement — not a substitute for it. Follow your local policy and ask a senior when in doubt.