Stability of common biochemical analytes in serum gel tubes subjected to various storage temperatures and times pre-centrifugation

Abstract

Blood samples collected in rural and remote areas of Australasia are often exposed to a range of environmental conditions prior to analysis in a laboratory. The aim of this study was to determine analyte stability of venous blood specimens in serum gel tubes exposed to a range of storage temperatures and times prior to centrifugation. Thirty healthy adult volunteers were enrolled in the study. Blood was collected into 11 serum gel separator tubes. All samples were allowed to clot at room temperature for 30 min. Two samples were centrifuged and analysed as controls. Nine samples were stored at 15, 25 or 35 degrees C for 4, 8 or 24 h, respectively, before centrifugation. Thirty-five biochemical analytes were measured on each sample. Most analytes remained stable in all storage conditions including sodium, total protein, albumin, bilirubin, alanine transferase, aspartate aminotransferase, alkaline phosphatase, gamma glutamyl transferase, creatinine kinase, lipase, cholesterol, triglycerides, transferrin, urate, C-reactive protein, vitamin B(12), thyroid-stimulating hormone, free thyroxine, free triiodothyronine, follicle-stimulating hormone, oestradiol, prostate-specific antigen, cortisol and vitamin D. Potassium, glucose, phosphate, creatinine, urea, ferritin, iron, lactate dehydrogenase, magnesium and calcium were not stable in at least one of the storage conditions. These results can be used to determine which analytes produce valid results despite exposure to variable storage conditions for up to 24 h prior to centrifugation. The majority of analytes were unaffected by a delay in centrifugation at a variety of temperatures, however, some important analytes were significantly affected.