Validation of an HPLC method for total homocysteine quantification in plasma

Abstract Introduction Homocysteine (Hcy) is a nonessential amino acid which links the methionine and the folate cycles. Hcy levels are increased in genetic disorders, such as classic homocystinuria and methylmalonic aciduria combined with homocystinuria. Other monogenic, multifactorial diseases and physiological conditions are also associated with high Hcy levels. The aim of this study is to validate a method to quantify Hcy in plasma. Material and methods A method to quantify Hcy in plasma by HPLC was validated, by determining the following parameters: specificity, linearity, precision, accuracy, and detection and quantification limits according ICH and EMEA guidelines. Homocysteine was measured in 43 healthy individuals, 2 patients with high levels of methylmalonic acid, and a previously diagnosed patient with classic homocystinuria. Results The method was able to identify and quantify Hcy without interferences. A linear behavior was observed in a range of 6–100 μM with r 2  = 0.9967. The precision and accuracy studies showed variation coefficients under 6%. The limits of detection and quantification were 3.12 μM and 6.25 μM, respectively. The 43 healthy individuals studied had normal Hcy levels. The patient with elevated urinary methylmalonic acid levels and the homocystinuria patient showed high Hcy levels. Conclusion The method is valid for the quantification of Hcy in plasma as it fulfills the requirements for validation of analytical methods. Its introduction into diagnostic and follow up algorithms is important in genetic diseases where this amino acid is increased.