A. Fernandez-marmiesse et al., Comparison of predose vs 2-h postdose blood metabolites/cyclosporine ratios in kidney and liver transplant patients, CLIN BIOCH, 33(5), 2000, pp. 383-386
Objectives: It has recently been suggested that when adjusting doses of cyc
losporine (CsA), determining its concentration in blood samples taken 2 h p
ostdose (C-2) is more clinically beneficial than using the predose concentr
ation (C-0). We determined C-0 and C-2 concentrations of CsA and their meta
bolites in samples taken from nine kidney and seven liver transplant patien
ts. Similarly, the so-called metabolic ratios (MR)-metabolites to CsA paren
t ratios-were calculated to characterise the most suitable moment of blood
sampling for obtaining a greater analytical specificity with monoclonal imm
unoassays.
Methods: The determination of CsA and CsA + metabolites was made using the
enzyme multiplied immunotechnique and the polyclonal fluorescence polarizat
ion immunoassay Abbott TDx, respectively.
Results: The poor correlation between C-0 and C-2 of CsA (n = 82, r = 0.387
, p < 0.001) is greatly inferior to that obtained between C-0 and C-2 of me
tabolites (n = 82, r = 0.912, p < 0.001). A highly significant difference (
p < 0.001) was found between MR0 values (mean 2.87 +/- 0.12, median 2.48) a
nd MR2 values (mean 1.73 +/- 0.09, median 1.46), although there is a good c
orrelation between them (r = 0.878, p ( 0.001).
Conclusions: The extent of the positive bias (deviation) of CsA immunoassay
s compared with the high-performance liquid chromatography results is relat
ed to the MR values. As the MR2 values are significantly lower than the cor
responding MR0, in practice a greater analytical specificity would be obtai
ned with the different monoclonal immunoassays in the determination of the
2 h postdose CsA concentration than in that of trough concentration. Copyri
ght (C) 2000 The Canadian Society of Clinical Chemists.