Fasting and post-methionine homocyst(e)ine levels in a healthy Australian population

Background: Plasma homocyst(e)ine CH[e]) is frequently measured in patients with occlusive vascular disease, but levels vary between populations and between laboratories. Aims: We sought to derive reference values for an Australian population over a wide age range. Methods: We measured plasma H(e) in the fasting state and after methionine loading in 116 volunteers selected at random from the Hunter districts of the New South Wales electoral roll and in 49 apparently healthy, active subjects recruited from the region's lawn bowling clubs. Reference ranges were derived for both sexes, in three age strata. We collaborated with two international laboratories in standardising our results. Results: Mean fasting H(e) levels were approximately 2.7 μmol/L higher in men than women, at all ages (95% CI for the difference, 1.2 to 4.1 μmol/L). Levels increased with age (approximately 1.0 μmol/L/decade, 95% CI 0.5 to 1.5) and were correlated with serum creatine (r=0.48), serum folate (r=-0.30), red cell folate (r=-0.25) and serum B₁₂ (r=-0.31) (all p<0.001). These results are similar to those reported in other populations. Conclusions: We have defined reference ranges for a typical Australian population, following careful laboratory standardisation. H(e) levels must be interpreted with regard to age, sex, renal function and vitamin B₁₂ and folate status.