IMMUNE-RELATED POTASSIUM-LOSING INTERSTITIAL NEPHRITIS - A COMPARISONWITH DISTAL RENAL TUBULAR-ACIDOSIS

Six patients with immune-related potassium-losing interstitial nephrit is (IRPLIN) are described, and compared with 34 patients with immune-r elated distal renal tubular acidosis (IRdRTA) and 24 with familial dis tal renal tubular acidosis (FdRTA). Close similarities were found betw een IRPLIN and IRdRTA. In our experience, both syndromes are confined to postpubertal women, and are characterized by systemic features of a utoimmune disease and a chronic interstitial nephritis which is probab ly immune-mediated and responsible for the functional tubular defects of the two syndromes. In IRPLIN, a renal potassium-losing state is the main consequence (probably mediated at least in part by renin and ald osterone hypersecretion secondary to renal sodium-losing), and urinary acidification is normal or minimally disturbed; consequently there is no systemic acidosis, and the syndrome is not complicated by nephroca lcinosis or renal bone disease. In IRdRTA, the renal tubular lesion al so usually causes potassium depletion, but the most prominent tubular fault is a defect in urinary acidification, which commonly causes meta bolic acidosis and often leads to nephrocalcinosis and bone disease. F amilial dRTA, in contrast, is equally prevalent in the two sexes and p resents at an earlier age than IRPLIN and IRdRTA. Patients with FdRTA and IRdRTA have a similar urinary acidification defect and propensity to acidosis, nephrocalcinosis and bone disease. FdRTA is frequently co mplicated by renal potassium-losing, but hypokalaemia is less common a nd less profound than in IRdRTA and IRPLIN, suggesting that immune-rel ated interstitial nephritis has a particular tendency to cause renal p otassium-losing.