Hypocalcemia
Also calledLow calcium · Decreased Ca2+ · Low Ca · Reduced serum calcium · Hypocalcaemia
Definition
A low serum calcium level (one review defines hypocalcemia as a serum calcium below 8 mg/dL). Low extracellular calcium prolongs phase 2 (the plateau) of the action potential, so the ST segment lengthens and the QTc interval is prolonged; the T wave may be upright, low, flat or sharply inverted.
Clinical noteThe prolonged QTc has been associated with torsades de pointes only in rare cases.
Sources
- El-Sherif N, Turitto G. Electrolyte disorders and arrhythmogenesis. Cardiol J. 2011;18(3):233-245. pubmed.ncbi.nlm.nih.gov/21660912/
- Pepe J, Colangelo L, Biamonte F, et al. Diagnosis and management of hypocalcemia. Endocrine. 2020;69(3):485-495. doi.org/10.1007/s12020-020-02324-2
- Drew BJ, Ackerman MJ, Funk M, et al. Prevention of torsade de pointes in hospital settings: a scientific statement from the American Heart Association and the American College of Cardiology Foundation. Circulation. 2010;121(8):1047-1060. doi.org/10.1161/CIRCULATIONAHA.109.192704
Last reviewed 2 October 2026. Every definition in the EKG Dictionary cites the guideline, consensus statement or original paper it comes from.