Plasma homocysteine in an Australian population sample

Objectives: To determine the plasma homocysteine concentrations in a sample of the New South Wales Central Coast population and relate them to their red cell folate and plasma vitamin B12 levels. Methods: Plasma samples were collected from 387 subjects (213 females; 174 males), with a mean age of 54.6 ± 15.5 years (mean ± sd) (females 54.2 ± 15.3; males 55.2 ± 15.8). Homocysteine was measured by HPLC. Red cell folate and vitamin B12 were measured by immunoassay. Results: The mean homocysteine concentrations were 10.3 ± 5.2 µM for the whole population sample, 10.0 ± 5.7 µM for the females and 10.6 ± 4.5 µM for the males. Notably, 14% of subjects had plasma homocysteine concentrations higher than 14 µM and 40% had concentrations higher than 10 µM. There was a positive correlation between the homocysteine concentration and age (r = 0.160; p = 0.002), a negative correlation between the homocysteine concentration and red cell folate (r = -0.247; p<0.001) and a negative .correlation between the homocysteine concentration and plasma vitamin B12 levels (r = -0.230; p<0.001). Conclusions: This sample of 387 subjects had plasma homocysteine concentrations similar to other population samples with 40% having levels above the recommended 10 µM threshold. Increasing age, decreased red cell folate and decreased plasma vitamin B12 appeared to be factors contributing to increased plasma homocysteine concentrations in this population sample.