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This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
Key points
- Severe: albumin-adjusted Ca²⁺ >3.0 mmol/L (or >3.5 = life-threatening). Two commonest causes: malignancy (acute) and hyperparathyroidism (chronic)
- Symptoms: confusion, drowsiness, thirst, polyuria, constipation, nausea, abdominal pain, bone pain. "Bones, stones, moans, groans"
- ECG: short QT interval, broad T waves. Severe: bradycardia, heart block
- Emergency treatment: (1) IV 0.9% NaCl 3–4 L/day, (2) IV zoledronic acid 4 mg over 15 min (onset 2–4 days), (3) calcitonin for rapid bridge
- Avoid thiazides (worsen hypercalcaemia). Loop diuretics only if fluid overloaded
- PTH level is KEY: high PTH = hyperparathyroidism. Low PTH = malignancy/sarcoidosis/vitamin D excess
Overview
This entry covers the emergency management of acute or severe hypercalcaemia. The full diagnostic workup and chronic management is covered in the endocrine hypercalcaemia entry. In the emergency setting, the priority is to identify life-threatening levels (>3.5 mmol/L), initiate aggressive IV fluid resuscitation, and administer IV bisphosphonate therapy while determining the underlying cause. Malignancy-associated hypercalcaemia is the most common cause in hospital (PTHrP secretion from squamous cell cancers, osteolytic metastases, or myeloma), while primary hyperparathyroidism is the commonest cause in the community.
Epidemiology
Hypercalcaemia is found in 1–3% of hospitalised patients. Malignancy-associated hypercalcaemia occurs in up to 30% of cancer patients and is a poor prognostic marker (median survival ~3 months). It is a common oncological emergency. In the emergency department, the combination of confusion + dehydration + renal impairment should prompt urgent calcium measurement.
Clinical Features
Symptoms
Confusion, drowsiness, coma (correlates with severity and rate of rise)
Severe thirst and polyuria
Nausea, vomiting, constipation, abdominal pain
Bone pain (metastases or hyperparathyroidism)
Signs
Dehydration (from polyuria + vomiting)
Reduced GCS
Short QT interval on ECG
Bradycardia, heart block (severe)
Investigations
First-line
Albumin-adjusted calciumMild 2.6–3.0, moderate 3.0–3.5, severe >3.5 mmol/L
PTHHigh = hyperparathyroidism. Low = malignancy, sarcoidosis, vitamin D intoxication
U&Es, eGFRAssess renal function (AKI from dehydration). Monitor during treatment
ECGShort QT, broad T waves. Severe: bradycardia, AV block
Second-line
Myeloma screenSerum protein electrophoresis, serum free light chains, urine Bence-Jones
Phosphate, ALP, vitamin DHelp differentiate cause
CXRLung mass, bony metastases, sarcoidosis (bilateral hilar lymphadenopathy)
Specialist
CT chest/abdomen/pelvisIf malignancy suspected — identify primary and staging
PTHrPElevated in humoral hypercalcaemia of malignancy
1
Immediate (severe or symptomatic)
- IV 0.9% NaCl: 3–4 L in first 24 h (adjust for cardiac function). Rehydration is the FIRST step
- IV zoledronic acid 4 mg over 15 min (or pamidronate 60–90 mg over 2–4 h). Onset 2–4 days, peak 7 days
- Calcitonin 4 IU/kg SC/IM 12-hourly: rapid onset (4–6 h) but tachyphylaxis within 48 h. Bridge until bisphosphonate works
- Avoid thiazides. Loop diuretics ONLY if fluid overloaded (not for hypercalcaemia itself)
- Monitor: Ca²⁺, U&Es, urine output. Urinary catheter if severely unwell
2
Treat underlying cause
- Malignancy: oncology review. Chemotherapy/radiation as appropriate
- Hyperparathyroidism: parathyroidectomy (see endocrine entry)
- Sarcoidosis: prednisolone 20–40 mg/day (suppresses 1-alpha hydroxylase)
- Drug-induced: stop offending agent (vitamin D, thiazide, lithium)
3
Refractory hypercalcaemia
- Denosumab 120 mg SC: if bisphosphonate-refractory or renal impairment (not renally cleared)
- Corticosteroids: if myeloma, lymphoma, sarcoidosis
- Dialysis: severe refractory cases or renal failure
Complications
- Cardiac arrest: Severe hypercalcaemia can cause arrhythmias and cardiac arrest. Potentiates digoxin toxicity
- AKI: Dehydration + direct renal tubular toxicity
- Pancreatitis: Acute pancreatitis can be triggered by hypercalcaemia
- Coma and death: Ca²⁺ >4.0 mmol/L is immediately life-threatening
UKMLA Exam Tips
- 1First step = IV saline rehydration (immediate effect). Bisphosphonate takes 2–4 days to work
- 2PTH high = hyperparathyroidism. PTH low = non-PTH cause (malignancy, sarcoid, vitamin D)
- 3Never give thiazides in hypercalcaemia. Short QT on ECG = hypercalcaemia (long QT = hypocalcaemia)
- 4Malignant hypercalcaemia is a POOR prognostic sign — discuss goals of care
- 5Myeloma: hypercalcaemia + renal failure + anaemia + bone pain in an elderly patient → myeloma screen
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