Homocysteinylation score of high-molecular weight plasma proteins.

Ultrafiltration rates (filterability) of protein-bound homocysteine (Hcy), unlike glutathione (Glt), are significantly decreased in patients with cardiovascular disorders, end-stage renal disease, and prothrombotic conditions. Reduced filterability of Hcy through 300,000 MWCO PES membranes in these groups of patients was observed, regardless of hyperhomocysteinemia (HHcy) degree. Filterability of Hcy, but not of glutathione, was impaired in plasma preparations. It is possible that the patients with impaired filterability of Hcy in mixed disulfide state are characterized by increased ability of partial Hcy retention by proteins and complexes with higher than albumin molecular weight. These findings led us to conclude that evaluation of protein-bound Hcy filterability may provide more complete diagnostic data, to interpret clinical significance of HHcy. The proposed Hcy filterability test may be performed as a simple laboratory procedure, in addition to conventional tests for total Hcy.