Potassium handling in health and disease: lessons from inherited tubulopathies.

UNLABELLED: The tight regulation of plasma potassium levels, a mostly intracellular cation, is essential given the severe consequences of hyper- and hypokalemia. Basic renal physiology studies in the past have identified the complex pathway of potassium reabsorption in the proximal tubule followed by the fine-tuning of its secretion or reabsorption at the distal tubule, including the thick ascending limb of Henle's loop, the distal convoluted tubule and the cortical collecting duct. Genetic studies in recent years have clarified the role of specific tubular channels and transporters in the pathogenesis of unique hyperand hypokalemic tubulopathies, some of them non-hypertensive (pseudohypoaldosteronism, Bartter and Gitelman syndromes) and others hypertensive by definition (including Liddle and Gordon syndromes). This article reviews the genetic and clinical spectrum of hypokalemic and hyperkalemic tubulopathies. ABBREVIATIONS: K: potassium, Na: sodium; Cl: chloride; BS: Bartter syndrome; PHA: pseudohypoaldosteronism; NKCC2: bumetanide-sensitive Na-K-2Cl- co-transporter; ROMK: inwardly rectifying K channel; ClC-Kb: basolateral Cl channel; TAL: thick ascending limb of Henle's loop; TSC: thiazide-sensitive NaCl co-transporter; CCD: cortical collecting duct; ENaC: epithelial Na channel.