For example, for increasing target concentrations up to 2.5 g/L, the Roche and Abbott methods
exhibited the smallest increase of variability.
The mean recovery of the spiked unconjugated bilirubin (expressed as a percentage of the target set by the reference laboratory for the high bilirubin concentration, excluding in-house results of manufacturers) was 86% for the Ortho VITROS method, 102% for the Siemens/Dade Behring method, 106% for the Roche method, 108% for the Beckman Coulter method, 110% for the Abbott method
, and 111% for the Siemens/Bayer method.
We conclude that with the Abbott method
, measured tHcy concentrations within the reference interval are lower for blood collected into NaF (P <0.001) and ACD-B tubes than for blood collected into EDTA, lithium heparin, and sodium citrate tubes.
In summary, Hcy concentrations measured by the Abbott method
in EDTA- and citrate-anticoagulated plasma agree well after a plasma-volume correction factor is taken into consideration.
Any Hb [A.sub.1c] method can in principle be used for this calibration, but we chose the Abbott method
, also utilizing the boronic acid affinity principle, because this made it possible to calibrate the present method to read both %GHb values and "standardized" %Hb [A.sub.1c] values.