The stability of clinical chemistry specimens during refrigerated storage for 24 hours

The authors investigated the stability of the tests comprising the SMA-6 and SMA-12 chemistry profiles during overnight refrigerated storage. Several constituents were found to undergo changes that were statistically significant when evaluated by a t test for paired comparisons. A recently published sequential method for judging sample stability was found to be somewhat less sensitive than the traditional statistical procedure. Only one determined value (CO2) underwent a change that was judged to be of medical significance. Two previously published criteria were used for this evaluation, one based on clinical judgment and the other on biologic variation. Variability of the results of repeat determination did not appear to be increased by overnight storage.