Stability of Plasma Homocysteine, S-Adenosylmethionine, and S-Adenosylhomocysteine in EDTA, Acidic Citrate, and Primavette™ Collection Tubes

After blood collection, homocysteine (Hcy) is generated in blood cells and is continuously released into the plasma. Stabilizing Hcy in blood samples requires immediate sample centrifugation and plasma separation from blood cells, sample cooling, or the use of special collection tubes(1)(2). To investigate the stability of Hcy and its precursors S -adenosyl-Hcy (SAH) and S -adenosyl-methionine (SAM), we collected fasting blood samples from healthy individuals (n = 8, age 25–46 years) and renal patients (n = 9, GFR 11–48 mL/min, 78–90 years). Patients were recruited from the Department of Internal Medicine IV-Nephrology and Hypertension of the Saarland University Hospital. Controls were selected among hospital employees. The local ethics committee approved the usage of blood samples from patients, and all participants gave informed consent. Samples were collected into EDTA, acidic citrate, and Primavette™ tubes. The samples were incubated at 4 °C or at room temperature for 0, 2, 6, and 24 h and were centrifuged afterward. A total of 357 samples were analyzed for Hcy by HPLC (Immundiagnostik) and by fluorescence polarization immunoassay (FPIA; Abbott). Plasma SAM and …