COMPARISON OF HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY AND IMMUNOASSAY METHODS FOR MEASUREMENT OF CYCLOSPORINE-A BLOOD-CONCENTRATIONS AFTER FELINE KIDNEY-TRANSPLANTATION

Objective-To compare two methods of whole blood cyclosporine A (CsA) m easurement in cats. Study Design-Whole blood samples were analyzed for CsA concentrations with use of high performance liquid chromatography (HPLC) and monoclonal immunoassay methods. Animals-Blood (n = 36 samp les) was obtained from six cats after renal transplantation. Methods-R esults were compared by linear regression analysis using both pooled a nd individual patient data. Eight samples were off-scale on the immuno assay and were excluded. Results-There was significant correlation bet ween CsA measured using HPLC and immunoassay methods (P < .001; r = .9 42; r(2) = .887). However, individuals varied nonrandomly from the mea n pooled patient data. Correlation between the assay methods was highe r for individual patients using data only from that specific individua l (mean r value = .976; r(2) = .955). Clinical utility of the immunoas say tie, results would prompt an appropriate CsA dosage adjustment) wa s good when based on individually derived conversion factors (27 of 28 [96.5%] of decision events). Conclusion-HPLC is superior for measurem ent of blood CsA concentrations in cats after kidney transplantation. However, an immunoassay may provide reliable information for CsA manag ement if a comparative database (HPLC v immunoassay) has been previous ly determined in a specific patient. Clinical Relevance-Locally availa ble monitoring of CsA by immunoassay in cats may provide significant a dvantages when shipping of blood samples to distant locations is requi red to obtain analysis by HPLC. These advantages may include cost and timeliness of results in circumstances where daily blood CsA concentra tions may be desired, such as when managing an acute rejection reactio n. (C) Copyright 1998 by The American College of Veterinary Surgeons.