Calibration of Abbott AxSYM Ferritin kit using the WHO Human Liver Ferritin International Standard 80/602

A commercial ferritin kit (Abbott AxSYM Ferritin) was calibrated using the WHO Human Liver Ferritin International Standard 80/602. The reconstituted WHO freeze-dried standard was diluted to obtain six concentration levels ranging from 10-840 micrograms/l. In the analysis of the data, logarithmic transformation of the results was performed in order to stabilize the variance. The AxSYM kit yielded slightly higher values than the WHO Ferritin Standard (p < 0.05). The relation between the AxSYM kit and the WHO Ferritin Standard (untransformed values) was described by a proportionality: FerritinAxSYM = 1.057 x FerritinWHO. WHO Ferritin Standard values of 12 and 15 micrograms/l (used as cut-off values for absent or small body iron reserves) yielded calculated AxSYM values of 12.7 and 15.9 micrograms/l. A WHO Ferritin Standard value of 30 micrograms/l (used threshold value for the presence of stainable bone marrow haemosiderin iron) yielded a calculated AxSYM value of 31.7 micrograms/l.