ABSTRACT
Diabetic nephropathy is the commonest cause of end-stage renal failure in the Western world. The incidence of DN rises rapidly over the first 15 to 20 years of diabetes to decline sharply afterwards. The stages of DN progress from normoalbuminuria to microalbuminuria to clinical proteinuria and finally to end-stage renal failure. Several studies proved the applicability of urinary albumin quantification in the early diagnosis of diabetic nephropathy. Several studies of different urinary proteins demonstrated the increased excretion of other high and low molecular mass proteins in different stages of diabetic nephropathy: macromolecular, e.g. transferrin and micromolecular proteins like alpha 1-microalbumin. Elevated urinary transferrin excretion rates have been reported in patients with type 2 diabetes and its complications. Therefore, the aim of the present study was to evaluate the role of transferrin as an early marker for the detection of nephropathy in Egyptian type 2 diabetic patients. Sixty Egyptian type 2 diabetic patients grouped according to the presence or absence of albumin in urine into three groups: group I consisted of 20 normoalbuminuric Egyptian type 2 diabetic patients, group II included 20 microalbuminuric Egyptian type 2 diabetic patients, and group Ill comprised 20 macroalbuminuric Egyptian type 2 diabetic patients. Twenty healthy subjects of matched age and sex were included as a control group. Laboratory investigations included FBG and 2 hours PPBG, HbA[1C] serum albumin, ALT, AST, prothrombin activity, blood urea, serum creatinine and creatinine clearance, and complete urine analysis. Determination of microalbuminuria in fresh urine samples was done using immunoturbidimetry. Estimation of urinary transferrin was done by immuno-nephelometry. Results: Type 2 diabetic patients who had frank proteinuria had a significantly longer duration of diabetes mellitus as compared to micro and norrnoalbuminuric patients. Type 2 diabetic patients with frank proteinuria had significantly higher FBG, PPBG and HbA[1C] levels as compared to normoalbuminuric type 2 diabetic patients and controls. Type 2 diabetic patients with frank proteinuria had significantly higher blood urea and serum creatinine and a significantly lower creatinine clearance as compared to norrnoalbuminuric type 2 diabetic patients and controls. Type 2 diabetic patients with frank proteinuria showed significantly higher urinary albumin and transferrin excretion as compared to normo-and microalbuminuric type 2 diabetic patients and controls. Also, microalbuminuric type 2 diabetic patients had significantly higher urinary albumin and transferrin excretion as compared to normoalbuminuric type 2 diabetic patients and controls. In normoalbuminuric type 2 diabetic patients, a negative correlation was observed between creatinine clearance and transferrinuria. In microalbuminuric type 2 diabetic patients, a strong positive correlation was found between albuminuria and transferrinuria. In type 2 diabetic patients with frank proteinuria, strong positive correlations were obtained between blood urea and serum creatinine and transferrinuria, while a strong negative correlation was observed between creatinine clearance and transferrinuria. However, no significant correlations were found in any of the type 2 diabetic groups between duration of the disease, blood pressure, FBG, PPBG, or HbA[1C] and transferrinuria. Urinary transferrin is a convenient diagnostic parameter of renal impairment in Egyptian type 2 diabetic patients. Transferrinuria could be considered as an early marker of diabetic nephropathy as compared to microalbuminuria