ERYTHROCYTE SODIUM-LITHIUM COUNTERTRANSPORT ACTIVITY AS A MARKER OF PREDISPOSITION TO HYPERTENSION AND DIABETIC NEPHROPATHY IN NIDDM

OBJECTIVE- To evaluate the potentiality of erythrocyte sodium-lithium countertransport activity (SLC) as a marker of predisposition to hypertension and diabetic nephropathy in non-insulin-dependent diabetes mellitus (NIDDM). RESEARCH DESIGN AND METHODS- We examined 96 patients with NIDDM and 26 healthy control subjects. SLC and other data were compared among subgroups of the patients classified on the basis of hypertension, family history of hypertension, and stages of nephropathy. Data were also analyzed by stepwise multiple regression analyses. RESULTS- SLC was significantly higher in patients with hypertension than in those with normotension and significantly higher in patients with a positive family history of hypertension than in the negative group. Further analysis revealed that a family history of hypertension has independent influence on SLC, but hypertension itself does not. SLC was significantly higher in patients with macroalbuminuria than with microalbuminuria and;higher in patients with microalbuminuria than with normoalbuminuria. In stepwise multiple regression analyses, a family history of hypertension was the most important determinant of SLC, and SLC was the most important determinant of nephropathy. CONCLUSIONS- These data suggest that SLC strongly reflects a predisposition to hypertension and that it can be a useful marker of diabetic nephropathy in NIDDM.