Figure 8.

Under normal circumstances, delivery of Na⁺ to the distal nephron is inversely associated with serum aldosterone levels. For this reason, renal K⁺ excretion is kept independent of changes in extracellular fluid volume. Hypokalemia caused by renal K⁺ wasting can be explained by pathophysiologic changes that lead to coupling of increased distal Na⁺ delivery and aldosterone or aldosterone-like effects. When approaching the hypokalemia caused by renal K⁺ wasting, one must determine whether the primary disorder is an increase in mineralocorticoid activity or an increase in distal Na⁺ delivery. EABV, effective arterial blood volume.