Stability of serum fructosamine during storage.

Stability of serum fructosamine during storage was evaluated in serum specimens obtained from 27 diabetic individuals. The samples were divided into six aliquots, which were stored at -20 degrees C and -70 degrees C for two, eight, and 16 months. The minor systematic differences between the six treatments contrasted with the considerable variation of individual specimens. The mean percentage changes in the six treatments ranged between -4.6% and 7.5%, whereas the changes in individual specimens ranged from -20% to 26.7%. Several factors evidently contribute to this variation, one being progressive in vitro glycation, especially at -20 degrees C. Small changes in fructosamine concentrations between consecutively drawn specimens, determined after storage, evidently should be interpreted cautiously. Low temperatures, at least -70 degrees C, are preferable to minimize pre-analytical variation during storage.