Plasma homocysteine measurement with ion exchange chromatography (Jeol Aminotac 500): a comparison with the Abbott IMx assay.
OBJECTIVE
We evaluated ion exchange chromatography (IEC) on the Jeol Aminotac 500 analyzer for total homocysteine (tHcy) determination and compared it with an immunoassay method using fluorescence polarization on an Abbott IMx analyzer.


METHODS
IEC method validation (linearity, limit of detection, precision, interference) was made according to the French Biology Society guidelines (Société Française de Biologie Clinique). Moreover, during a 2-month period, 55 plasma samples from patients scheduled for routine tHCy measurement were assayed by both methods for determining correlation.


RESULTS
The IEC method was found linear up to at least 190 micromol/l, and the limit of detection was 1.6 micromol/l. Precision was studied with 3 controls at 6, 15 and 30 micromol/l. Intra-assay coefficients of variation (n = 14) were 8.3, 3.1 and 2.3%, respectively, and inter-assay coefficients of variation (n = 15) were 9.6, 5.1 and 4.9%, respectively. No interference was found with other sulfur-containing amino acids (methionine, cysteine). An excellent agreement was found between IEC and fluorescence polarization (Deming regression; y = 0.99x - 1.23; r = 0.97; p < 0.001).


CONCLUSIONS
The IEC method for tHcy measurement shows adequate precision and correlates highly with the IMx assay. The IEC method is more time-consuming but less expensive in reagent cost and allows simultaneous determination of plasma methionine concentration which may help to explain the underlying mechanism responsible for hyperhomocysteinemia.
Service de Biochimie A, Hôpital Saint-Antoine, AP-HP, Paris, France.
Pascal
P
Pernet
Gaëlle
G
Cuzon
Soo-Kyung
SK
Lim
Nicole
N
Labau
Aïcha
A
Laghzal
Michel
M
Vaubourdolle
D002852:Chromatography, Ion Exchange; D016231:Fluorescence Polarization Immunoassay; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D012044:Regression Analysis
D006710:Homocysteine