The homocysteine distribution: (mis)judging the burden.

The nonfasting plasma total homocysteine (P-tHcy) concentration was measured in a random sample of 3025 Dutch adults aged 20-65 years (main study). The positively skewed distribution had a geometric mean of 13.9 micromol/L in men and 12.6 micromol/L in women. Blood of the main study was not cooled or centrifuged immediately after drawing. A stability study (n = 26) indicated that this could have resulted in a small (0.4 micromol/L) overestimation of the means. A comparative study (n = 88), and a reproduction of these results in an entirely different population (n = 213), showed a systematic difference in P-tHcy concentration of -2.4 micromol/L between our laboratory (Nijmegen, the Netherlands) and that in Bergen, Norway. With the information of the additional studies we provided precise and valid data of the Dutch P-tHcy distribution, from which we conclude the status in the Netherlands is worse than in other European countries. Furthermore, we showed that comparison of P-tHcy data is complicated unless the interlaboratory differences are known. @ 2001 Elsevier Science Inc.