Serum homocysteine levels and paraoxonase 1 activity in preschool aged children in Greece

Background: Over the past decade, it has been well established that elevated total serum homocysteine (tHcy) in adults is associated with increased risk of cardiovascular and thromboembolic diseases. Since risk factors for such diseases are established at a young age, the aim of the present study was to measure serum tHcy levels in 134 (71 boys, 63 girls) randomly selected healthy preschool children aged 4-6 years (mean 5.1), and to investigate possible correlation with paraoxonase 1 (PON1) activity, an antioxidant enzyme that contributes to the antiatherogenic properties of high-density lipoprotein (HDL). Methods: tHcy was determined using an IMX tHcy assay (FPIA). PON1 was measured by a spectrophotometric method at 412 nm. Results: Mean serum tHcy was 7.71±2.35 μmol/L. A relatively significant percentage (15.6%) of boys and girls had elevated serum tHcy levels (>10 μmol/L). tHcy levels were slightly higher in girls compared to boys (8.20±2.80 vs. 7.29±1.79 μmol/L, respectively; p<0.11). There was no significant interaction between age and tHcy levels. Mean PON1 activity was 124.86±66.62 U/L. No statistical difference in enzyme activity was observed between boys and girls (126.81±69.99 vs. 121.74±64.78 U/L) was observed. On the contrary, a weak negative relationship between tHcy concentration and PON1 activity was detected, with Pearson's correlation coefficient of r= -0.27. Conclusions: The significant percentage of elevated tHcy levels observed in healthy preschool cases and the negative tHcy correlation with PON1 activity are reported for the first time. Since children with a family history of cardiovascular disease have higher levels of serum Hcy, tHcy screening in children, even of this age, in relation to other parameters, such the protective PON1, might prove a useful prevention procedure for the genetic risk of premature atherosclerosis.