Hyperkalemia By James L Lewis III, MD, Brookwood Baptist Health and Saint Vincent's Ascension Health, Birmingham Reviewed / Revised Sep 2021 | Modified Sep 2022 View Patient Education Etiology Symptoms and Signs Diagnosis Treatment Key Points Topic Resources ECG patterns in hyperkalemia Factors Contributing to Hyperkale... Hyperkalemia is a serum potassium concentration > 5.5 mEq / L (> 5.5 mmol / L), usually resulting from decreased renal potassium excretion or abnormal movement of potassium out of cells.