Effect of Erythropoietin on Urinary Liver-Type Fatty-Acid-Binding Protein in Patients with Chronic Renal Failure and Anemia

Abstract

Background/Aim: The urinary liver-type fatty-acid-binding protein (L-FABP) level reflects the clinical progression of chronic kidney disease. We conducted a study to determine whether administration of erythropoietin (EPO), which is produced in response to hypoxic stress, affects urinary protein excretion and L-FABP levels in patients with chronic renal failure (CRF) and anemia. Methods: The study was an interventional trial that included 20 anemic CRF patients (median serum creatinine level 2.0 mg/dl, range 1.3–2.9 mg/dl; median hemoglobin concentration 9.2 g/dl, range 8.2–9.8 g/dl; median estimated glomerular filtration rate 20.5 ml/min, range 15.0–28.0 ml/min; group A). Recombinant EPO (12,000 U twice/month) was given to these patients for 6 months. Urinary protein, L-FABP, 8-hydroxy-2′-deoxyguanosine, and hemoglobin levels were measured before and 3 and 6 months after treatment. Twenty nonanemic CRF patients were enrolled as controls (group B). Results: After 6 months, the hemoglobin level was increased as compared with the baseline level in group A treated with EPO (median 11.3 g/dl, range 9.3–13.8 g/dl, vs. median 9.2 g/dl, range 8.2–9.8 g/dl; p < 0.01) but not in the untreated group B (median 11.8 g/dl, range 10.2–13.0 g/dl, vs. median 12.1 g/dl, range 10.8–13.4 g/dl; not significant). The urinary protein excretion was decreased as compared with the baseline level in group A (median 1.2 g/day, range 0.6–1.9 g/day, vs. median 1.9 g/day, range 1.1–2.6 g/day; p < 0.01) but not in group B (median 1.4 g/day, range 0.7–2.2 g/day, vs. median 1.6 g/day, range 0.7–2.3 g/day; not significant). The urinary L-FABP level was also decreased as compared with the baseline level in group A (median 50.0 µg/g creatinine, range 7.5–90.0 µg/g creatinine, vs. median 115.0 µg/g creatinine, range 20.0–225.0 µg/g creatinine; p < 0.01) but not in group B (median 82.0 µg/g creatinine, range 15.5–158.0 µg/g creatinine, vs. median 76.0 µg/g creatinine, range 25.0–138.5 µg/g creatinine; not significant). The glomerular filtration rate changed little throughout the study period in either group. The urinary 8-hydroxy-2′-deoxyguanosine level was decreased as compared with the baseline level in group A (median 22.0 ng/mg creatinine, range 8.0–30.0 ng/mg creatinine, vs. median 38.5 ng/mg creatinine, range 14.0–68.0 ng/mg creatinine; p < 0.01) but not in group B (median 33.0 ng/mg creatinine, range 9.0–56.0 ng/mg creatinine, vs. median 30.0 ng/mg creatinine, range 10.0–54.0 ng/mg creatinine; not significant). Conclusion: EPO supplementation may ameliorate renal tubular damage, in part, due to a reduction of oxidative stress in CRF patients with anemia.