Urine liver fatty acid binding protein and chronic kidney disease progression

Abstract

Excretion of the tubular protein liver fatty acid binding protein (L-FABP) is a potential novel biomarker of renal dysfunction. We examined whether urine L-FABP excretion adds prognostic information to the well-established risk markers, blood pressure (BP), albumin excretion and baseline GFR, regarding progression of chronic kidney disease (CKD). In a prospective study design a cohort of 74 stage 3-4 CKD patients (age 61 ± 13 years) were included. Glomerular filtration ratio (GFR, ⁵¹Cr-EDTA-clearance), 24-hour ambulatory BP, 24-hour urinary albumin/creatinine ratio (UAC) and urinary L-FABP/creatinine ratio (U-L-FABP/C) were determined at baseline and after 18 months of follow-up. For comparison 25 age-matched healthy controls were included. The U-L-FABP/C was elevated in CKD patients when compared to controls (mean U-L-FABP/C 2.3 [95% CI 1.7–2.9] μg/mmol vs 0.6 [0.5–0.7] μg/mmol, p < .001). In CKD patients, log U-L-FABP/C at baseline and at follow-up were positively associated (Pearson correlation coefficient r = 0.74, p < .001). Baseline log U-L-FABP/C was negatively correlated with baseline GFR (r = −0.32, p < .001) and directly correlated with UAC (r = 0.67, p < .001). The relative change in GFR from baseline to follow-up correlated with baseline UAC (p < .001), 24-hour systolic BP (p = 0.05) and log U-L-FABP/C (p < .001). Using multiple regression analysis adjusting for baseline GFR, UAC, BP, age and gender, baseline log U-L-FABP/C was associated with a decline in GFR only in patients with UAC <3 mg/mmol (n = 29, p = 0.001) and not in patients with UAC ≥3 mg/mmol (n = 44, p = 0.21). In conclusion urine L-FABP/C is permanently elevated in CKD patients, but only associated with GFR decline in those without albuminuria.

Keywords:

• Liver fatty acid binding protein
• chronic renal failure
• albuminuria
• glomerular filtration rate
• biomarkers

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The study was supported by Medical Sciences, Danish Council for Independent Research and Karen Elise Jensens Foundation, Denmark.