Objective: To determine reference intervals and interquartile ranges for total homocysteine (Hcy) folate and cobalamin in Icelandic men and women and to evaluate the correlation of Hcy to serum levels of the vitamins folate and cobalamin.
Material and methods: Blood samples were collected from 449 individuals over a period of three months, 291 men (mean age 48.3 years) and 158 women (mean age 49.8 years). Plasma Hcy was measured by a HPLC method with fluorescence detection; folate and cobalamin levels in serum were measured by an electroimmunochemical method on an ELECSYS system from Roche.
Results: The reference interval for Hcy, between 2.5% and 97.5% fractiles, estimated by parametric statistics, are 6.2-17.5 micromol/L for men and 4.8-14.1 micromol/L for women. Similarly the 95% reference intervals for folate and cobalamin were estimated using parametric statistics. A significant negative correlation was found between concentrations of folate and Hcy for both men and women (p<0.01) with a correlation coefficient of -0.39 and also between cobalamin and Hcy where the correlation coefficient is -0.20.
Conclusions: Reference interval for Hcy from the general presumed healthy population is estimated here for the first time in Icelandic men and women and will be of value in cardiovascular risk assessments. The negative correlation between Hcy and folate and also Hcy and cobalamin, is in agreement with results from other studies and suggests that an improved vitamin status might be beneficial in lowering Hcy in a section of the population as has been suggested in numerous studies in other countries.