Urinary excretion of liver fatty acid-binding protein in health-check participants

Messenger RNA of liver fatty acid-binding protein (L-FABP) is expressed in proximal tubules of the kidney, and a certain amount is excreted into urine. We analyzed factors relating to the urinary L-FABP excretion in health-check participants. We measured L-FABP in the first morning urine by ELISA in 715 men and 193 women 30-79 years of age who entered a 2-day hospitalized health checkup program. In addition to the routine physical examination and laboratory tests, plasma high-sensitivity C-reactive protein (HSCRP) was assayed. In 150 healthy subjects, urinary L-FABP averaged 3.6 +/- 0.2 microg/g creatinine, whereas the values were significantly increased in patients with hypertension (5.2 +/- 0.4, P = 0.010), diabetes mellitus (5.5 +/- 0.5, P < 0.001), and chronic hepatitis (5.8 +/- 1.0, P = 0.022). Urinary L-FABP excretion was significantly greater in women than in men when the value was related to creatinine. In regression analysis in men, urinary L-FABP was positively correlated with fasting plasma glucose (r = 0.103, P = 0.033) and plasma HSCRP (r = 0.135, P = 0.006). It is suggested that renal production and urinary excretion of L-FABP are increased in situations in which arteriosclerosis is promoted, such as hypertension, diabetes mellitus, and cardiovascular inflammation.