Abstract:

Objective To establish a reference interval of serum ferritin in adults in Shanghai by indirect method. Methods A total of 27 775 individuals with ferritin determination from January 2021 to October 2022 in Zhongshan Hospital of Fudan University were enrolled. By the Turkey method to eliminate outliers，18 264 individuals were enrolled ultimately，and a reference interval of ferritin was established by the Hoffmann method. Totally，2 486 apparently healthy adults from March 2023 to April 2023 in Zhongshan Hospital of Fudan University were enrolled to validate the ferritin reference interval. The reference interval establishment population and validation population were classified into male group，female ≤50 years old group and female >50 years old group based on sex and ages. Additionally，207 females >50 years old with anemia from March 2022 to April 2023 in Zhongshan Hospital of Fudan University were enrolled to evaluate the application value of the reference interval of ferritin. The correlation between ferritin and sex，ages was evaluated by linear-regression analysis. Results There was statistical significance in ferritin levels among male group，female ≤50 years old group and female >50 years old group（P<0.001）. There was no correlation between male ferritin levels and ages（r²=0.003，P>0.05），while female ferritin levels were positively correlated with ages（r²=0.125，P<0.05）. The reference intervals were established for males，females ≤50 years old and females >50 years old，respectively，by the Hoffmann method. The reference intervals were 33.4-1 000.0 μg·L^-1 for males and 4.8-341.0 μg·L^-1 for females ≤50 years old，27.4-765.0 μg·L^-1 for females >50 years old. The upper and lower limits of the established reference intervals were different from those of the current reference intervals. The validation pass rates of established reference intervals were 98.59% for males and 95.82% for females ≤50 years old，97.38% for females >50 years old，which were higher than those of the current reference intervals（85.89%，78.76% and 60.26%，respectively）（P<0.001）. The established reference intervals can better distinguish individuals with abnormal iron metabolism indicators. Conclusions Serum ferritin exhibits sex and age differences. Serum ferritin reference intervals established by indirect method is suitable for the population in Shanghai than the current reference intervals.

Key words: Ferritin, Indirect method, Reference interval, Anemia, Shanghai