2004 Volume 47 Issue 4 Pages 291-295
The clinical evaluation of the effect of a low-protein diet (LPD) on diabetic nephropathy in outpatients is hampered by the standardization in estimating the protein intake.To simplify estimation, we studied the relationship between protein intake and urinary urea nitrogen (UN) concentration in patients with diabetic nephropathy. Subjects were 51 patients divided into 2 groups based on creatinine clearance (Ccr): group A with Ccr of 30-60 ml/min and group B with Ccr of <30ml/min. The daily protein intake was calculated from total UN excretion in 24-hour urine collection. Urine samples were used to determine the ratio of UN per creatinine concentration (UN/Cr).Group A showed a significant positive correlation between daily protein intake and UN/Cr in urine samples. According to an ROC curve, 4.46 UN/Cr as the cutoff point yielded 90.48% sensitivity and 77.78% specificity for 0.8 g/kg/day of protein intake. Group B showed no correlation between protein intake and urinary UN/Cr.These results suggest that UN/Cr in urine samples is a useful indicator of daily protein intake in patients whose Ccr is 30-60ml/min.
