Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.
Tetany, carpopedal spasm, laryngospasm, seizure, prolonged QT or arrhythmia may deteriorate rapidly. Society guidance treats severe biochemical hypocalcaemia, generally adjusted calcium below 1.9 mmol/L, or symptomatic hypocalcaemia at any measured concentration as a medical emergency, while ionised calcium is decisive in critical illness.
Action: Use ABCDE, ECG monitoring and venous access; confirm calcium, magnesium, phosphate and renal function without delaying therapy. Give intravenous calcium gluconate through the current Society or local protocol, repeat to clinical effect, then arrange an infusion and cause-specific replacement with endocrine support.
Synopsis
Recognise neuromuscular and cardiac hypocalcaemia, deliver monitored calcium when severe, and correct magnesium, vitamin D and parathyroid causes durably.
Confirm true hypocalcaemia with albumin-adjusted calcium or ionised calcium; low total calcium from hypoalbuminaemia alone does not require calcium replacement.
Symptoms reflect the ionised fraction and speed of fall, so acute postoperative hypocalcaemia can be severe before total calcium reaches an extreme value.
Paraesthesia, cramps, carpopedal spasm, tetany, laryngospasm, seizure and QT prolongation are important acute discriminators.
Investigation priorities
01
Ionised calcium or albumin-adjusted calciumFirst step
Confirm biologically meaningful deficiency and quantify severity in the relevant clinical state.
Management branches
EmergencyStabilise symptomatic calcium deficiency
Tetany, seizure, airway symptom, arrhythmia or severe measured hypocalcaemia is present.
Start ABCDE and continuous ECG, obtain ionised or adjusted calcium, magnesium, phosphate and renal bloods, and summon senior acute support.
Give 10% calcium gluconate using the current Society or local dilution and bolus protocol, reassessing symptoms and ECG and repeating if necessary.
Key medicines
Calcium gluconate 10%For severe or symptomatic adult hypocalcaemia, Society guidance uses 10–20 mL diluted in 50–100 mL of 5% glucose over about 10 minutes with ECG monitoring, repeated if necessary, then an infusion titrated by specialist protocol.
Magnesium replacementReplace through the current oral or intravenous local regimen selected for severity, symptoms, kidney function and measured deficit, with slower and lower treatment when renal excretion is impaired.
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.