many years ago I used the HPLC method (being the reference method) but for clinical diagnostics you will find an enzymatic method much easier. An extensive review about HOCY, comparing methods etc etc is the Refsum paper Article Facts and Recommendations about Total Homocysteine Determina...
Do not forget to take care of pre-analytical factors, see for example Article Pre-analytical Conditions Affecting the Determination of the...
I also developed an HPLC method for determination of homocysteine long time ago when commercial methods were not available yet. Point of attention are:
- pre-analytical phase (mainly blood sampling) as indicated by Jos Wielders
- reduction of disulphide bridges: homocysteine is bound to albumin by disulphide linkage. Different reducing agents have been proposed giving different total concentrations because of differences in reducing power.
- choice of method depends on instrument availability and expertise. Most clinical laboratories use commercial methods. MS or HPLC-MSMS are expensive instruments and require skilled technicians.
- anyway, choose a method with abundant information in literature concerning normal values and comparability with other methods as general accepted decision limits for this risk factor are at the upper limit of the normal values.