Measurement of Cyclosporine by Liquid Chromatography and Three Immunoassays in Blood from Liver, Cardiac, and Renal Transplant Recipients

In an effort to replace HPLC for whole-blood determination of cyclosporine (CsA), we compared HPLC with radioimmunoassay (RIA; INCSTAR, Cyclo-Trac SP assay), fluorescence polarization immunoassay (FPIA; Abbott TDx), and in-house modified enzyme-multiplied immunoassay technique (EMIT; Syva Co.). For blood samples from 200 various transplant recipients, RIA = 1.262 (HPLC) - 8.16, r = 0.983; FPIA = 1.200 (HPLC) + 19.90, r = 0.981; and EMIT = 1.038 (HPLC) + 11.28, r = 0.985. For segregation by transplant type, RIA, FPIA, and EMIT demonstrated positive biases of 27%, 12%, and 3%, respectively, for liver transplant recipients (n = 50) when compared with HPLC. Heart transplant recipients (n = 50) gave positive bias values of 23%, 14%, and 4% for RIA, FPIA, and EMIT, respectively. Adult renal transplant recipients (n = 50) demonstrated positive bias values of 30%, 31%, and 0% for RIA, FPIA, and EMIT, respectively. For pediatric renal transplant recipients (n = 50), positive biases of 40%, 31%, and 9% were obtained for RIA, FPIA, and EMIT, respectively. We conclude that the modified EMIT represents the best replacement for HPLC.