THE CONCOMITANTS OF ELEVATED ERYTHROCYTE SODIUM-LITHIUM COUNTERTRANSPORT ACTIVITY IN DIABETIC NEPHROPATHY - A CRITICAL-ASSESSMENT

Elevated erythrocyte sodium-lithium counter-transport activity is an intermediate phenotype of essential hypertension among Caucasians, and may also associate with kidney disease in type 1 (insulin-dependent) diabetes mellitus. Evidence supporting the hypothesis that an inherited predisposition to essential hypertension may thus partly identify with the genetic background of susceptibility to diabetic nephropathy is, however, controversial. This review discusses the possible points of controversy, with emphasis upon the need to standardize the manifest heterogeneity in the current techniques of measurement, as well as upon the clinical concomitants and interpretation of elevated sodium-lithium counter-transport activity in type 1 diabetes mellitus. Large family studies may be required in order to single out the independent contributions of genes and environment to sodium-lithium countertransport activity in type 1 diabetes mellitus. However, the original hypothesis that genes underlying elevated sodium-lithium countertransport in essential hypertension and in diabetic nephropathy may also reflect in part a predisposition to diabetic kidney disease cannot be rejected on the basis of current evidence.