Pre-Analytical Errors in Blood Homocysteine Assays

Abstract

Blood homocysteine is a major biomarker for cardiovascular as well as other disorders. Several published studies reported inconsistent homocysteine levels with variable ranges. The reference intervals are variable hence the comparison of studies is difficult. Pre-analytical factors that influence homocysteine testing such as the storage, processing and transportation of blood samples, often pose severe problems in clinical settings. Total homocysteine levels were determined in 36 blood samples collected from normal healthy subjects by HPLC with fluorescence detection. The results indicate that delay separated samples stored at ambient temperature have significantly higher values than the delay separated samples stored at 2-8ºC. The rise was 41.9 % in 3 hours that amounts to a rate of ≈14 % per hour. It is concluded that there is a strong need for standardization of blood sample collection and processing in homocysteine assays. It is strongly advocated that homocysteine should never be measured in serum and that it is ideal to use plasma specimens preserved at 2-8ºC.