Abstract
This review will primarily address methodological aspects of homocysteine measurement, highlighting changes since the subject was comprehensively reviewed in 1993, and will bring together practical information of relevance to laboratory planning or to providing an analytical service including homocysteine measurement. Because the physiological state of the patient during blood collection is often neglected, and because it has become apparent that the bloodsampling procedure may contribute considerably more variation to measurement of homocysteine than the total variation of the analytical procedures, the review will pay particular attention to the critical roles of controlled blood collection and sample processing.