Stability of total plasma homocysteine in perinatology

BACKGROUND: Typical assay methods for total homocysteine in human plasma involve EDTA-containing whole blood. Unfortunately, rapid increases of the plasma homocysteine concentrations due to cellular export are observed when the EDTA-containing samples are not stored on ice and processed shortly after collection. This is a cumbersome procedure in perinatal settings, whereby delivery usually takes place at unpredictable times. METHODS: The stability of homocysteine was assessed from six placental and neonatal blood samples collected in citrate buffer. Samples were stored at 4 degrees C and tested at regular intervals for the first 24 h. RESULTS: There was no statistical difference in homocysteine concentrations as observed over the study storage period (mean coefficient of variation [CV] 4.9%). CONCLUSIONS: Citrated samples can be left in a refrigerator for at least 24 h with no effect on the plasma homocysteine concentrations.