Certain components of interest are sensitive to degradation by the process of multiple freeze-thaw cycles.
One of the more commonly measured enzymes, alanine aminotransferase (ALT), does not withstand multiple freeze-thaw cycles, and falsely decreased results may occur.
The immunoglobulins (IgA, IgG, IgM) are also known to decrease upon repeated freeze-thaw cycles, while plasma renin levels are known to increase after repeated freeze-thaw cycles.
Laboratory procedures and protocols for handling long-term storage should be adhered to in order to prevent inaccurate test results.
