Ferritin variability may occur due to several factors, including:
- Differences in assay methodology and instrumentation
- Reference range calibration and standardization
- Biological variability, as iron markers (particularly ferritin) may fluctuate based on inflammation, recent dietary intake, and physiologic status
- Pre-analytical variables, such as timing of collection, fasting status, and sample handling
As an acute phase reactant, ferritin can rise within hours of inflammation or infection as macrophages and liver cells sequester and release ferritin. Inflammation can increase ferritin by approximately 30-90% depending on the phase of the inflammatory response.
In instances when ferritin is elevated, it is important to contextualize the result with a patient-focused history around the time of collection. Assess symptoms or events within the preceding 24–72 hours, including fever, upper respiratory or other infections, acute injury, strenuous exercise, or inflammatory flares. Clarifying recent vaccinations, procedures, or new-onset pain or swelling can also be helpful, as these may transiently elevate ferritin. This short-interval history often explains unexpected increases and helps distinguish iron status from an acute phase response.
Ferritin decline is highly variable, depending on ongoing iron utilization and infection and inflammation resolution.
References
- Anemia of Inflammation. Ganz T. The New England Journal of Medicine. 2019;381(12):1148-1157. doi:10.1056/NEJMra1804281.
- Adjusting Plasma Ferritin Concentrations to Remove the Effects of Subclinical Inflammation in the Assessment of Iron Deficiency: A Meta-Analysis. Thurnham DI, McCabe LD, Haldar S, et al. The American Journal of Clinical Nutrition. 2010;92(3):546-55. doi:10.3945/ajcn.2010.29284.