Some kinetic considerations in high cut-off hemodiafiltration for acute myoglobinuric renal failure.
The kinetics of myoglobin in severe rhabdomyolysis and dialysis-dependent myoglobinuric acute kidney injury (Mb-AKI) is still not well elucidated, and more detailed knowledge could improve the now empiric use of rapid extracorporeal myoglobin removal by high cut-off (HCO) hemodialysis treatments. Eighteen adult patients with severe dialysis-dependent Mb-AKI (median serum concentration of myoglobin 57.4 mg/L) participated in the prospective clinical study, assessing myoglobin kinetics during HCO hemodiafiltration (HCO HDF). High initial serum concentrations of myoglobin (median 57.4 mg/L), together with protracted myoglobin appearance in the blood, indicated a large accumulation of myoglobin in body fluids. Extra-renal endogenous metabolic myoglobin clearance was delayed, with a slow exponential fall in serum myoglobin (t½ 35 h). A mean myoglobin clearance of 90-94 mL/min, a reduction ratio of 80%, and a rapid exponential fall (t½ 1 h) in serum and dialysate myoglobin were achieved by HCO HDF. Half of the cumulative myoglobin removal was accomplished in 3-5 h, with an additional removal of 7% each hour thereafter. A 2.4-fold rebound in serum myoglobin followed the HCO procedures. Large amounts of myoglobin are released into the circulation, and its endogenous metabolic clearance in dialysis-dependent Mb-AKI is slow. Owing to its rapid and highly efficient myoglobin elimination, HCO HDF may represent a valuable tool in the initial management of severe Mb-AKI, with a potential for earlier application in the future.