Abstract

Background: The most frequent cause of acute kidney injury (AKI) needing renal replacement therapy is sepsis, with the prognosis of patients with septic AKI worse than for other causes of this disease. Recent studies have shown that fibroblast growth factor-23 (FGF-23) levels, one of the phosphaturic and prognostic factors in chronic kidney disease, are also elevated in patients with AKI and correlate with an increased risk of death or a need for dialysis. In addition, FGF-23 was found to inhibit the extra-renal synthesis of 1,25-dihydroxyvitamin D by human monocytes. Therefore, the elevated expression of FGF-23 may play a crucial role in defining the immune response to vitamin D and this, in turn, may be a key determinant of infection in patients. Continuous renal replacement therapy (CRRT) is often essential for the treatment of septic AKI. However, reports related to the influence of CRRT on serum FGF-23 levels are lacking. In this study, we undertook preliminary in vitro investigations evaluating the effect of different types of CRRT membranes on FGF-23 adsorption.
Methods: To study how FGF-23 is adsorbed by hemofiltration fiber, in vitro experiments were performed based on a batch method using three types of fiber: polysulfone (PS), polymethyl methacrylate (PMMA), and acrylonitrileco-methallyl sulfonate surface treatment (AN69ST) fiber.
Results: The adsorptive properties of the various membranes were determined from measuring changes in the concentration of FGF-23 in a solution containing the membrane after incubation for 60 or 240 minutes. The amount of FGF-23 adsorbed by an AN69ST membrane was significantly more than for other membranes (P < 0.01). The amounts adsorbed by PS and PMMA membranes were similar.
Conclusions: We found an AN69ST membrane has a greater capacity for FGF-23 adsorption than two other membranes tested. Although this is an in vitro study, we believe the present findings indicate an exciting new direction in the treatment of septic AKI and highlight the necessity of acute clinical investigations using AN69STCRRT.

DOI: 10.7754/Clin.Lab.2015.150717