Heparinized blood provides equivalent results to EDTA in the CEDIA and FPIA cyclosporine immunoassays, thus facilitating routine cyclosporine determination.

BACKGROUND

CsA measurements are routinely used to allow adequate CsA dosage adjustments. CsA assays routinely require EDTA anticoagulated whole blood; EDTA has been preferred due to differences seen when using heparinized blood in the past. We hypothesized that with new, robust assays, heparinized blood might be appropriate for measuring CsA levels.

METHODS

CsA levels from EDTA samples and heparinized samples were compared using the CEDIA assay on a BeckmanCoulter DXC. Also, CsA levels from heparinized blood were compared using the CEDIA assay (BeckmanCoulter) and the FPIA assay (Abbott Axsym).

RESULTS

CsA levels from EDTA blood (x) and heparinized blood (y, n=81) showed very good correlation without deviation from linearity by Passing-Bablok analysis (y=-2.4524+1.0210x). In 187 samples obtained from heparinized blood, CsA levels determined by using the CEDIA assay (x) or the FPIA assay (y) also correlated equally well by Passing-Bablok analysis (y=6.1922+1.0221x), also without deviation from linearity.

CONCLUSION

CsA determination from heparinized blood is easy to perform and accurate with the two assays described and evaluated. Using heparinized blood reduces handling time as well as hands on time. We suggest that this methodology be formally evaluated by the manufacturers for inclusion into CE labelling of their products to allow improved laboratory work flow.