Hypocalcaemia Overview

  • Normal serum corrected calcium = 2.2 – 2.6 mmol/L.
  • Mild-moderate hypocalcaemia = 1.9 – 2.2 mmol/L.
  • Severe hypocalcaemia = < 1.9 mmol/L.

Causes of Hypocalcaemia

  • Hypoparathyroidism
  • Vitamin D deficiency
  • Acute pancreatitis
  • Hyperphosphataemia
  • Hypomagnesaemia
  • Diuretics (frusemide)
  • Pseudohypoparathyroidism
  • Congenital disorders (e.g. DiGeorge syndrome)
  • Critical illness (e.g. sepsis)
  • Factitious (e.g. EDTA blood tube contamination)

Symptoms of Hypocalcaemia

  • Neuromuscular excitability
  • Carpopedal spasm
  • Tetany
  • Chvostek sign
  • Trousseau sign
  • Seizures

ECG changes in Hypocalcaemia

  • Hypocalcaemia causes QTc prolongation primarily by prolonging the ST segment.
  • The T wave is typically left unchanged.
  • Dysrhythmias are uncommon, although atrial fibrillation has been reported.
  • Torsades de pointes may occur, but is much less common than with hypokalaemia or hypomagnesaemia.
ECG-QT-changes-Hypocalcaemia-Hypercalcaemia 2

ECG Examples

Example 1
ECG Hypocalcaemia QTc 500


  • QTc 500ms in a patient with hypoparathyroidism (post thyroidectomy) and serum corrected calcium of 1.40 mmol/L
  • Reproduced from Nijjer et al. (2010)

Example 2
ECG Hypocalcemia long QT


  • QT prolongation in a patient with DiGeorge’s syndrome and serum calcium of 1.32 mmol/L
  • Reproduced from Kar et al. (2005)

Example 3
  • Hypocalcaemia causing a long QTc (510ms)

Related Topics


  • Nijjer S, Ghosh AK, Dubrey SW. Hypocalcaemia, long QT interval and atrial arrhythmias. BMJ Case Reports 2010; doi:10.1136/bcr.08.2009.2216 [full text].
  • Kar PS, Ogoe B, Poole R, Meeking D. Di-George syndrome presenting with hypocalcaemia in adulthood: two case reports and a review. J Clin Pathol. 2005 Jun;58(6):655-7. [PMID 15917421]

LITFL Further Reading

Advanced Reading




Emergency Physician in Prehospital and Retrieval Medicine in Sydney, Australia. He has a passion for ECG interpretation and medical education | ECG Library |

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