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Management of Hypocalcaemia

Introduction

The reference range for serum adjusted calcium* is 2.2-2.6mmol/L. Acute hypocalcaemia can be life-threatening and may require urgent treatment. In severe cases intravenous calcium forms the mainstay of initial therapy, but it is essential to ascertain the underlying cause and commence specific treatment as early as possible.

*Ensure you check serum adjusted calcium. This is the serum calcium concentration adjusted for the serum albumin concentration and should be used to guide replacement.

Symptoms of hypocalcaemia, such as muscle cramps, paraesthesia, tetany and carpopedal spasm, typically develop when serum adjusted calcium falls below 1.9mmol/L. However, this threshold varies and symptoms also depend on the rate of fall.

Assessment / monitoring

Initial biochemical investigations:

  • Serum adjusted calcium and phosphate
  • Parathyroid hormone (PTH)
  • Urea and electrolytes
  • Magnesium
  • Vitamin D

A 12-lead ECG should be performed as there is a significant likelihood of QT prolongation, and cardiac monitoring may be required.

Monitor serum calcium concentrations regularly to judge response and review treatment. Serum bone profile should be checked daily initially and then three times a week when stable. On discharge, advise the GP to check the serum bone profile every fortnight until concentrations are stable.

Drug therapy / treatment options

Mild Hypocalcaemia: serum adjusted calcium 1.9-2.2mmol/L and asymptomatic

Commence oral calcium supplement and adjust to patient's individual requirements. For example, Calcichew Forte Chewable Tablets, 2 tablets twice a day or, in patients with swallowing difficulties, Calvive 1000 Effervescent Tablets, 2 tablets twice a day (unlicensed doses**).

  • If post-thyroidectomy, repeat serum calcium 24 hours later. Then if:
    • Serum adjusted calcium >2.2mmol/L, patient may be discharged with plan to re-check serum calcium within one week.
    • Serum adjusted calcium remains between 1.9-2.2mmol/L, increase Calcichew Forte Chewable or Calvive 1000 Effervescent, to 3 tablets twice a day (unlicensed doses**).
    • Patient remains in mild hypocalcaemic range 72 hours post-operatively despite calcium supplementation, start alfacalcidol oral 0.25microgram daily. Alfacalcidol is restricted to specialist initiation; contact a senior member of medical staff to discuss use.
  • If vitamin D deficient, commence oral vitamin D supplementation: load with colecalciferol as per the GGC Vitamin D deficiency guideline (refer to flowchart 2 under osteomalacia).
  • If patient has hypomagnesaemia, stop any precipitating drug and administer IV magnesium (see the Management of Hypomagnesaemia guideline).

**These are unlicensed doses of Calcichew Forte Chewable and Calvive 1000 Effervescent Tablets. Review on discharge and, if appropriate, prescribe the licensed dose (1 tablet once a day).

Severe Hypocalcaemia: serum adjusted calcium <1.9mmol/L and/or symptomatic

This is a medical emergency. Administer calcium gluconate 10% IV as follows:

  • Initially, give calcium gluconate 10% IV 10-20ml in 50-100ml sodium chloride 0.9% or glucose 5% over 10 minutes with ECG monitoring. This can be repeated until the patient is asymptomatic.
  • Followed by a continuous IV infusion:
    • Dilute calcium gluconate 10% IV 100ml (10 x 10ml ampoules) in one litre of sodium chloride 0.9% or glucose 5% and infuse at 50-100ml/hour. Check serum adjusted calcium every 4-6 hours. Titrate the infusion rate to achieve normocalcaemia, and continue until treatment of the underlying cause has taken effect.

 

Guideline reviewed: February 2026

Page updated: August 2026