Freeze/thaw stability of transferrin, and reference values obtained with kinetic nephelometry

To determine whether transferrin is stable to repeated freezing and thawing, we used blood specimens from 100 normal adults. Their transferrin concentrations were determined by a laser kinetic nephelometric immunoassay. The sera were stored at 4 degrees C and analyzed the next day (day 1). Specimens 1-25 were stored at -20 degrees C and assayed again on days 3, 4, 8, 16, 22, and 43. Specimens 26-100 were stored at 4 degrees C and analyzed again on day 2. Transferrin proved to be stable to repeated freezing and thawing. Normal reference values with respect to sex and age are given, as determined with the Baker 420 Immunological Nephelometer.