Optimization of routine plasma homocysteine monitoring.
An elevated plasma homocysteine (Hcy) level is now considered to be an important risk factor in arterial and venous thromboembolic events. As a result of this relatively recent finding, there has been a dramatic increase in the number of requests for Hcy measurement. In our laboratory, this demand has been met by employing an automated immunoassay and improving the pre-analytical handling of blood samples. An automated fluorescent polarization immunoassay (FPIA) gave similar results to a reference high-pressure chromatographic (HPLC) method (r2 = 0.98, enzyme immunoassay = 0.998 HPLC - 0.3) and excellent between-run reproducibility (coefficient of variation <3%). The new assay also required less specialized technical input, and improved the sample throughput two-fold. Pre-analytical stability of plasma Hcy concentrations in blood samples is crucial to the accuracy of Hcy monitoring. This stability was improved 10-fold by adopting the anticoagulant acidic citrate instead of ethylenediamine tetraacetic acid for Hcy screening by FPIA. Acidic citrate dramatically inhibits time-related plasma contamination by red-cell Hcy, resulting in improved accuracy and a reduced number of 'spoiled' specimen discards.
O'Broin
S D
SD
Department of Haematology, St. James's Hospital, Dublin, Ireland. nutrition@stjames.ie
Kelleher
B P
BP
McPartlin
J
J
O'Gorman
P
P
Browne
M
M
White
B
B
Smith
O P
OP
D016903:Drug Monitoring / Q000379:methods*; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D007118:Immunoassay / Q000379:methods; D012680:Sensitivity and Specificity
D006710:Homocysteine