Stabilization of Homocysteine Concentration in Whole Blood

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Abstract
Homocysteine (Hcy) is a cytotoxic ((1)), sulfur-containing amino acid that increasingly appears to be an independent risk factor for coronary artery disease, stroke, and peripheral occlusive arterial disease (POAD) ((2)(3)(4)) when present at high plasma concentrations. In addition to several physiological factors that can increase Hcy concentration in blood such as vitamin B6, B12, or folate ((5)) deficiency and renal insufficiency ((6)), there is an artificial increase of Hcy concentration in whole blood after blood collection. This severe preanalytical problem is due to the well-known, time-dependent release of Hcy from erythrocytes ((7)) in the isolated blood sample, even when stabilization is attempted with different additives such as EDTA, NaF, or heparin/NaF ((8)(9)(10)). The result of this release is a falsely increased plasma Hcy concentration, unless plasma is separated from blood cells immediately after blood collection. We describe a method to overcome this problem for making the routine determination of Hcy possible for institutions where sample transport is critical.