RENAL FUNCTIONAL RESERVE IN INSULIN-DEPENDENT DIABETIC CHILDREN

Background: Microalbuminuria has been shown to be predictive for clini cal diabetic nephropathy. Renal functional reserve (RFR), as a respons e to protein loading in a short period of time, is a parameter to asse ss the ability of kidneys to increase the glomerular filtration rate ( GFR). The aim of this study was to predict the early phase of diabetic nephropathy by measuring urinary albumin level and RFR capacity in pa tients with insulin-dependent diabetes mellitus (IDDM). Methods: Twent y-two patients with IDDM were studied: 11 with a disease duration of l ess than 5 years (group 1) and II with a disease duration of more than 5 years (group 2). As the control group, 15 healthy children (group 3 ) were included in the study. At the beginning of the study, glucose w as measured and the urinary albumin/creatinine ratio was calculated. A verage glycosylated hemoglobin (HbA(1)c) over I year was determined. A fter protein loading (red meat containing 2 g/kg of protein), the crea tinine clearance was calculated at each hour for a duration of 4 h. Th e RFR was accepted as the peak percentage increase in GFR over the bas eline value. Results: Although metabolic control in group 2 was better , the RFR in group 2 was significantly lower than in group 1 (P < 0.05 ). Urinary microalbumin levels between the groups did not differ (P > 0.05). In two patients in whom microalbuminuria was detected, the RFR was much lower. Conclusions: Detecting lower RFR levels in patients wi th normal urinary albumin excretion, as well as in patients with micro albuminuria, may support the idea that the RFR capacity is more sensit ive than microalbuminuria in assessing the early phase of diabetic nep hropathy.