Abstract
Liver-type fatty acid binding protein (L-FABP) is a 14 kDa protein expressed in the cytoplasm of human renal proximal tubule cells. Renal L-FABP expression is up-regulated and the urinary excretion level of renal L-FABP is increased by various stressors, such as hyperglycemia, urinary protein, and tubular ischemia. Therefore, the measurement of urinary L-FABP is useful for the early diagnosis of kidney disease with renal tubular disorders. In our study, we evaluated the basic performance of “Nordia®L-FABP” for the measurement of L-FABP in human urine by latex turbidimetric immunoassay. The result indicates that the variation coefficients for within-run and day-to-day run reproducibilities were 1.3 to 2.2% and 1.2 to 3.9%, respectively. Furthermore, the linearity was also tested by serial sample dilution and was observed up to a dilution of 210 ng/mL, and the detection limit was 1.2 ng/mL. Compared with the conventional reagent, it has sufficient basic performances, and the correlation test was good (y = 1.12x + 0.53, r = 0.976). There was no significant interference caused by the addition of the following interfering substances: conjugated bilirubin, hemoglobin, and chyle. On the other hand, ascorbic acid may affect the measured levels of L-FABP depending on the concentration of coexisting substances. These results indicate that the new method, applicable to automated clinical chemistry analyzers, is useful for rapid measurement of L-FABP in human urine, and this assay kit may be beneficial in routine tests because it is useful for the early diagnosis of kidney disease.
