title: Cyclosporine blood concentrations determined by specific versus nonspecific assay methods.
abstract: Cyclosporine blood concentrations were simultaneously determined by radioimmunoassay (RIA) and high-performance liquid chromatography (HPLC) at multiple points in time in two patients receiving cyclosporine for immunosuppression following liver transplantation. Radioimmunoassay levels always exceed those determined by HPLC; however, the divergence between the two methods increased as serum bilirubin concentration increased, with HPLC:RIA ratios generally less than 0.3 when serum bilirubin concentrations exceeded 10.0 mg/dL. These preliminary results suggest that retention of immunoactive cyclosporine metabolites due to imparied liver function may account for RIA-determined cyclosporine concentrations that greatly exceed those measured by HPLC.
mesh_terms: D000328:Adult; D001663:Bilirubin / Q000097:blood; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003524:Cyclosporins / Q000009:adverse effects / Q000097:blood*; D005069:Evaluation Studies as Topic; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D016031:Liver Transplantation; D008297:Male; D008875:Middle Aged; D011863:Radioimmunoassay / Q000379:methods
chemical_list: D003524:Cyclosporins; D001663:Bilirubin