FABP4 and membranoproliferative glomerulonephritis: In 25 patients who had nephrotic-range proteinuria (≥ 3.5 g/gCr), including MCNS (n = 9), MN (n = 7), DN (n = 3), IgA vasculitis (n = 3), focal segmental glomerular sclerosis (n = 2) and membranoproliferative glomerulonephritis (n = 1), the AUC of receiver operating characteristic curve analysis for U-FABP4 level to predict MCNS was 0.92, and the cut-off point of U-FABP4 level by the Youden index was 0.78 μg/gCr (Fig. 2), indicating that a level of U-FABP4 ≤ 0.78 μg/gCr predicts MCNS.