Analysis of the stability of alanine aminotransferase (ALT) levels in donor samples

This study was designed to 1) analyze the stability of serum alanine aminotransferase (ALT) activity in nonseparated donor samples stored at room temperature (RT) over 72 hours and 2) compare ALT levels of paired samples stored at RT and 4 ° C over the same time period. The study showed that mean ALT activities for samples stored at RT increased at all assay times and that those stored at 4 ° C decreased (0.54 IU/L over 72 hours). Although the mean increase in activity of the RT samples over 72 hours (1.45 IU/L) was statistically significant, it was of little practical significance. For example, based on the frequency distribution of the 311 RT samples from this study, and using a cut-off value of 69 IU/L, only one unit of blood would have been eliminated based on the difference between time zero and 72 hours. It was concluded that RT would be the storage of choice for 72 hours, since the tendency of ALT levels to decrease during storage at 4 ° C could make possible the inclusion of borderline donor units in the blood supply.