In humans, uL‐FABP level is mostly determined by proximal tubular injury rather than liver damage,33, 34 and sL‐FABP is not correlated with uL‐FABP in patients with CKD.35 The increase in L‐FABP expression in the proximal tubules and subsequent secretion of L‐FABP into the tubular lumen occurs in transgenic mice expressing human L‐FABP in the kidneys when they exhibit renal failure.19, 36 Therefore, we suggest that uL‐FABP is mainly derived from proximal tubular cells in cats. Here, FABP1 is linked to Renal insufficiency.