Cation shifts in hypokalemia

Reciprocal cation shifts of K⁺, H⁺, and Na⁺ between the cells, including renal tubular cells, and the extracellular fluid. In the presence of hypokalemia, K⁺ moves out of the cells down a concentration gradient. Since the cell anions (primarily, proteins and organic phosphates) are unable to cross the cell membrane, electroneutrality is primarily maintained by the entry of Na⁺ and H⁺ into the cell. The increase in cell H⁺ concentration may be responsible for the increased H⁺ secretion and HCO₃^– reabsorption seen with hypokalemia. On the other hand, hyperkalemia causes H⁺ and Na⁺ to leave the cells, resulting in a fall in H⁺ secretion and HCO₃^– reabsorption.