Enhanced erythrocyte Na + /H + exchange predicts diabetic nephropathy in patients with IDDM

Summary Diabetic nephropathy develops in a subset of patients with an apparently hereditary predisposition. Microalbuminuria and elevated arterial pressure have been proposed as predictors of nephropathy but both appear when renal damage is impending. Enhanced sodium-hydrogen exchange in the cell membranes of diabetic patients is an early marker of diabetic nephropathy but its predictive value has not been assessed. In this study, sodium-hydrogen exchange was measured in erythrocytes as an initial velocity of amiloride-inhibited H ⁺ efflux (pH 6.35–6.45) into a Na ⁺ -containing medium (pH 7.95–8.05) in 156 non-microalbuminuric insulin-treated diabetic patients (98 women, 58 men, age 33 ± 8 years, diabetes duration prior to enrollment 15 ± 4 years) during 8 years of follow-up. Enhanced erythrocyte sodium-hydrogen exchange predicted diabetic nephropathy alone and in association with a familial tendency to hypertension/nephropathy with 86 and 96 % sensitivity, and 80 % specificity. Thus, sodium-hydrogen exchange appears to detect a subset of diabetic patients prone to develop renal damage, in whom a more intensive treatment modality might be considered. [Diabetologia (1998) 41: 201–205] Received: 23 April 1997 and in final revised form: 15 September 1997