Clinical evaluation of urinary excretion of liver-type fatty acid-binding protein as a marker for the monitoring of chronic kidney disease: A multicenter trial

To confirm the clinical usefulness of the measurement of urinary liver-type fatty acid-binding protein (L-FABP) in chronic kidney disease (CKD), we carried out a multicenter trial. Clinical markers were measured in patients with nondiabetic CKD (n = 48) every 1 to 2 months for a year. We divided patients retrospectively into progression (n = 32) and nonprogression (n = 16) groups on the basis of the rate of disease progression, then assessed several clinical markers. Initially creatinine clearance (Ccr) was similar in the 2 groups; however, the urinary L-FABP level was significantly higher in the former group than in the latter (111.5 vs 53 mu g/g creatinine, P < .001). For the monitoring CKD, we set the cutoff values for urinary L-FABP and urinary protein at 17.4 mu g/g creatinine and 1.0 g/g creatinine, respectively. Urinary L-FABP was more sensitive than urinary protein in predicting the progression of CKD (93.8% and 68.8%, respectively). However, urinary protein showed greater specificity than did urinary L-FABP (93.8% and 62.5%, respectively). Over time, the progression of CKD tended to correlate with changes in urinary L-FABP (r = -.32, P < .05), but not in urinary protein (r = .18, not significant). The dynamics of urinary protein differed from that of urinary L-FABP, which increased as Ccr declined. Urinary L-FABP is more sensitive than urinary protein in predicting the progression of CKD. Urinary excretion of L-FABP increases with the deterioration of kidney function. Urinary L-FABP is therefore a useful clinical marker in the monitoring of CKD.