Hypocalcaemia

Acute hypocalcaemia that is severe (<1.9 mmol/L) or symptomatic can be life-threatening and necessitates urgent treatment. It is often initially picked up when a patient has low ionised calcium on the blood gas as bone profiles are not routinely measured for every admission.

Symptoms & Signs

  • Perioral & digital paraesthesia
  • Positive Trousseu’s and Chvostek’s signs
  • Tetany & carpopedal spasm
  • Laryngospasm
  • ECG changes: prolonged QT, bradycardia & other arrhythmias
  • Seizure

Causes

  • Total thyroidectomy (or parathyroidectomy) / hypoparathyroidism
  • Severe Vitamin D deficiency
  • Hypomagnesaemia (consider secondary to PPIs)
  • Pancreatitis
  • Rhabdomyolysis
  • Drugs – loop diuretics, glucocorticoids, gentamicin, phosphates, theophylline, some cytotoxics
  • Large volume blood transfusions

Investigations

  • Bone Profile, U&Es, Magnesium, Vitamin D, PTH
  • Consider amylase/lipase (pancreatitis) & creatine kinase (rhabdomyolysis) as clinically indicated

Treatment

You should use either your local guidelines or the guidelines produced by the Society for Endocrinology.

Mild (>1.9 mmol/L)
  • Commence oral replacement using Sandocal (2 tablets BD) or Adcal (3 tablets BD) or any other available
  • Treat the underlying cause e.g.:
    • Stop causative drugs
    • Vitamin D – load with around 300,000 units as per local guidelines
    • Hypomagnesaemia – IV Magnesium (usually requires 24 mmol or 6g in 24h) & stop any precipitating drugs e.g. PPIs
    • Thyroidectomy/Parathyroidectomy – may need 1-alpha hydroxylated Vitamin D. This should be started with specialist advice
Severe (<1.9 mmol/L or symptomatic)
  • This is a medical emergency & should be treated whilst on a cardiac monitor
  • Example regime could be:
    1. 10-20ml 10% calcium gluconate in 50-100ml of 5% dextrose over 10 minutes
    2. Calcium gluconate infusion – 100ml 10% calcium gluconate in 1L 0.9% saline/5% dextrose at 50-100ml/h
  • Treat the underlying cause as above
  • Ensure referral to the endocrinology team

References & Further Reading

  • Society for Endocrinology Guidelines
  • UK Medicines Information
  • Hamilton, R.J., 2018. Tarascon adult emergency pocketbook. Jones & Bartlett Learning.
  • Lewis III, J. L., 2018. Hypocalcemia. MSD Manual Professional Version.
  • Turner, J., Gittoes, N., Selby, P. and Society for Endocrinology Clinical Committee, 2016. SOCIETY FOR ENDOCRINOLOGY ENDOCRINE EMERGENCY GUIDANCE: Emergency management of acute hypocalcaemia in adult patients. Endocrine connections, 5(5), p.G7.

Written By Dr Akash Doshi (ST4)
Previous version by Dr Shoaib Hussain

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