Renal functional reserve in insulin dependent diabetic children

Abstract

Background: Microalbuminuria has been shown to be predictive for clinical diabetic nephropathy. Renal functional reserve (RFR), as a response to protein loading in a short period of time, is a parameter to assess 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 patients with insulin-dependent diabetes mellitus (IDDM). Methodr:Twenty-two patients with lDDM were studied: 11 with a disease duration of less than 5 years (group 1) and I1 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 was measured and the urinary albumidcreatinine ratio was calculated. Average glycosylated hemoglobin (HbA,c) over 1 year was determined. After protein loading (red meat containing 2 gkg of protein), the creatinine clearance was calculated at each hour for a duration of 4 h. The RFR was accepted as the peak percentage increase in GFR over the baseline 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 with normal urinary albumin excretion, as well as in patients with microalbuminuria, may support the idea that the RFR capacity is more sensitive than microalbuminuria in assessing the early phase of diabetic nephropathy. Key wordsdiabetic nephropathy, insulin-dependent diabetes mellitus, microalbuminuria, renal functional reserve.Diabetic nephropathy develops in 30-40% of patients with insulin-dependent diabetes mellitus (IDDM).' Prediction of high-risk patients is important for the early detection of nephropathy. Increases in urinary microalbumin and low molecular weight tubular proteins are important parameters that are commonly used in the early detection of renal damage.Renal functional reserve (RFR) is the ability of kidneys to increase glomerular filtration rate (GFR) under stimuli.

Tc-99m diethylenetriamine pentaacetic acid (DTPA) renal function reserve estimation: is it a reliable predictive tool for assessment of preclinical renal involvement in scleroderma patients?

“…In the current study, the microalbuminuric SSc patients showed a statistically significant negative association with baseline GFR and RFR. The latter was predictive of subclinical renal disease in 24/30 (80%) SSc patients compared to 8/30 (26.7%) using microalbuminuria, and such wide discrepancy was reported in previous studies that concluded the detection of abnormal RFR in diabetic patients with or without microalbuminuria is more sensitive than microalbuminuria in assessing the early phase of diabetic nephropathy [22,37]. Also, the timed urine collections being the standard for detecting microalbuminuria are considered cumbersome, inconvenient, and subjected to collection inaccuracies being a limiting factor in contrary to GFR and RFR estimation.…”

Renal functional reserve in patients with Type 1 diabetes mellitus

“…In macroalbuminuric patients, RFR was found to be positive but decreased [14], positive in patients with GFR above 60 ml.min-1.1.73m2-1 and negative in patients with GFR below 60 ml.min-1.1.73m2-1 [14] or absent [19]. In studies where albuminuria was not defined or the groups of the patients were nonhomogeneous, RFR was found to be positive but decreased [21][22][23] or negative [24]. There are several possible explanations for the inconsistency of RFR results.…”

“…A further reason for inconsistent results is that the groups of patients studied were not homogeneous, defined for example only by diabetes duration [23] or differing in presence of retinopathy or concomitant drug therapy [19].…”