Hyperkalemia
Also calledHigh potassium · Elevated K+ · High K · Raised serum potassium · K+ elevation
Definition
An elevated serum potassium level that affects the myocyte membrane potential and cardiac conduction and produces a recognizable sequence of ECG changes, although the ECG is an insensitive guide to the level. The classic progression is tall, peaked, narrow-based, symmetric T waves (described at about 5.5 to 7.0 mmol/L) with a shortened QT interval, then PR prolongation with flattening and loss of P waves and QRS widening, and finally a sine-wave pattern, with ventricular tachycardia or ventricular fibrillation at the highest levels.
Clinical noteECG changes correlate imperfectly with the measured level: in one review half of patients with a potassium above 6.5 mEq/L showed no ECG changes, so a normal tracing does not exclude dangerous hyperkalemia.
Sources
- Levis JT. ECG diagnosis: hyperkalemia. Perm J. 2013;17(1):69. doi.org/10.7812/TPP/12-088
- El-Sherif N, Turitto G. Electrolyte disorders and arrhythmogenesis. Cardiol J. 2011;18(3):233-245. pubmed.ncbi.nlm.nih.gov/21660912/
- Montague BT, Ouellette JR, Buller GK. Retrospective review of the frequency of ECG changes in hyperkalemia. Clin J Am Soc Nephrol. 2008;3(2):324-330. doi.org/10.2215/CJN.04611007
Last reviewed 2 October 2026. Every definition in the EKG Dictionary cites the guideline, consensus statement or original paper it comes from.