Management of Hypocalcaemia
The reference range for adjusted serum calcium is 2.2 - 2.6mmol/L. Acute hypocalcaemia can be life-threatening and may necessitate 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.
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
- 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 e.g. sandocal 1000, 2 tablets twice a day* (unlicensed dose) and adjust to patient's individual requirements.
- 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 sandocal 1000 to three tablets twice a day (unlicensed dose)*.
- 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 300,000units over 6-10 weeks e.g. 50,000units weekly for 6 weeks followed by a maintenance dose of 800-1000units daily.
- If patient has hypomagnesaemia, stop any precipitating drug and administer IV magnesium (see Management of Hypomagnesaemia guideline).
*This is an unlicensed dose of sandocal. Review on discharge and if appropriate prescribe the licensed dose (1 tablet daily).
Severe Hypocalcaemia: serum adjusted calcium <1.9mol/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 glucose 5% IV 50-100ml 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. Titrate the rate to achieve normocalcaemia and continue until treatment of the underlying cause has taken effect.
Content last updated October 2019.