Hypokalemia: Defining the problem Hypokalemia is amongst the most common electrolyte disturbances reportedly seen in clinical practice.1 The normal range for serum potassium levels is defined as between 3.5-5.0 mmol/l.2 Below the lower limit, hypokalemia is categorized as mild when the serum potassium level is 3-3.4 mmol/L, moderate when the serum potassium level is 2.5-3 mmol/L, and severe when the serum potassium level is less than 2.5 mmol/L.1 This condition is associated with an increased rate of mortality, owing to its association with progression of cardiac and kidney disease and interstitial fibrosis. Hence, an improved understanding of the underlying mechanisms of potassium homeostasis is important for practitioners.