Updated ferritin reference intervals for the Roche Elecsys® immunoassay

Reference intervals (RI) for ferritin are the subject of some controversy, with indications that changes in lifestyle and demographics (e.g., obesity) have limited the validity of RIs established decades ago. Package insert RIs for the Roche Elecsys® immunoassay do not include expected values for pediatric (<17-20 years) or geriatric (>60 years) individuals; furthermore the female ranges were established in mostly premenopausal volunteers. To establish more robust RIs, we utilized 5 years of retrospective patient data from physician-ordered ferritin measurements and excluded results from patients with diagnoses known to affect ferritin concentrations. Ferritin results from 1438 unique patients aged 7 months to 91 years were included in the study. Continuous RIs were fitted for females (n = 951) and males (n = 487) as a function of age; these were then divided into clinically relevant sex-specific age breaks. RIs were established for pre-adolescent (<10 years), adolescent (10-17 years) and adult males, and for pediatric (<18 years), adult (18-50 years) and older (>50 years) females. Established RIs were verified using specimens obtained from healthy donors.