Preanalytical conditions for the measurement of plasma total homocysteine: genotype C677T MTHFR dependent non-fasting variations and anticoagulant effects on stability

The pre-analytical conditions required for the measurement of plasma total homocysteine (tHcy) are poorly standardized and coercive for epidemiological studies. Our objective was an assessment of different parameters in order to simplify the pre-analytical conditions. The need for the fasting has been evaluated by the determination of fasting and post prandial tHcy: 2 h after a meat containing 1,2 g of methionin. The influence of the C677T MTHFR genotypes on postprandial tHcy variations has been studied. The possibility to transport the sample at ambient temperature has been evaluated by comparison of the tHcy values between EDTA samples conserved in ice and several anticoagulant samples (EDTA, NaF + K oxalate and EDTA + NaF + K oxatate) kept at ambient temperature (2 h and 4 h). The plasma conservation during 24 h at +4 degrees C and during 7 days at -20 degrees C has been studied. The results show significant and genotype dependent postprandial variations on tHcy determination. The use of EDTA + NaF + K oxalate as anticoagulant avoid the need for sample transport in ice. Whatever is the anticoagulant used, the conservation of plasma is possible during 24 h at +4 degrees C or 7 days at -20 degrees C is possible. (c) 2007 Elsevier Masson SAS. Tous droits reserves.