A charge selectivity impairment in protein permselectivity is present in type 2 diabetes.

Acta Diabetologica Volume 30, Issue 3, September 1993, Pages 138-142 A charge selectivity impairment in protein permselectivity is present in type 2 diabetes (Article) Morano, S.a, Pietravalle, P.a, De Rossi, M.G.a, Mariani, G.a, Cristina, G.a, Medici, F.a, Sensi, M.a, Andreani, D.a, Di Mario, U.b a Istituto di Clinica Medica 2 (Endocrinologia), University 'La Sapienza', Rome, Italy b Department of Clinical and Experimental Medicine, University of RC-Catanzaro, Catanzaro, Italy View references (27) Abstract A possible loss in kidney charge permselectivity of proteins before any manifestation of nephropathy has been sought in type 2 (non-insulin-dependent) diabetes by assessing the clearances of proteins differing in charge and/or size (anionic and cationic immunoglobulins, albumin). Eighty-five consecutive outpatients with type 2 diabetes were studied and compared with 101 normal subjects. Of the patients, 14.1% wree microalbuminuric and 2.3% macroalbuminuric. A significant increase in protein clearances was observed in diabetic patients in comparison with normal subjects: the median of albumin clearance was 0.09 ml/min, interquartile range (IR) 0.04-0.31 (P<0.01 vs normals); that of anionic immunoglobulins (IgG4) 0.02 ml/min, IR 0.01-0.05 (P<0.005 vs normals); and that of neutral/cationic immunoglobulins (IgG) 0.13 ml/min, IR 0.07-0.19 (P<0.01 vs normals). The anionic/cationic immunoglobulin ratio median was 0.22, IR 0.11-0.43, and exceeded the upper limit of normal values in 29.4% of all patients. IgG4 clearance was positively correlated with albumin clearance (r=0.72) and with IgG clearance (r=0.98). Nevertheless anionic immunoglobulin clearance was increased in a number of patients (17.3%) with normal IgG excretion and even in patiens (15.1%) with normal albumin clearance. Clearances of IgG4 and IgG, but not that of albumin, were correlated with the duration of diabetes. Thus, an increased anionic/cationic IgG ratio in type 2 diabetes highlights a charge selectivity defect in protein permselectivity; this selective proteinuria may reflect more accurately than does microalbuminuria an early kidney abnormality in this form of diabetes.