Utility of Serum Ferritin for Predicting Myalgic Encephalomyelitis/Chronic Fatigue Syndrome in Patients with Long COVID.
Yamamoto, Yukichika, Otsuka, Yuki, Tokumasu, Kazuki et al. · Journal of clinical medicine · 2023 · DOI
Quick Summary
This study looked at 234 people with long COVID to understand why some developed ME/CFS (a severe fatigue condition) while others didn't. Researchers found that people who developed ME/CFS had significantly higher levels of ferritin, a protein that stores iron, in their blood compared to those with long COVID fatigue alone or no fatigue. The finding was especially strong in women, suggesting that a simple blood test measuring ferritin might help predict who is at risk of developing ME/CFS after COVID-19.
Why It Matters
ME/CFS remains diagnostically challenging, with no established biomarkers; identifying serum ferritin as a potential predictor could facilitate earlier recognition and stratification of high-risk long COVID patients. This finding opens new avenues for understanding the biological mechanisms linking infection-triggered inflammation to ME/CFS pathophysiology. For patients, a simple blood test could help predict disease trajectory and enable earlier intervention.
Observed Findings
Serum ferritin levels were significantly higher in the ME/CFS group (median 193.0 μg/L, IQR 58.8-353.8) compared to non-ME/CFS (98.2 μg/L, IQR 40.4-251.5) and no-fatigue groups (86.7 μg/L, IQR 37.5-209.0).
Ferritin levels correlated positively with Fatigue Assessment Scale (FAS) and Self-Rating Depression Scale (SDS) scores.
Female patients showed particularly prominent elevations in serum ferritin in the ME/CFS group.
ME/CFS patients had higher thyrotropin and lower growth hormone levels compared to other groups.
Insulin-like growth factor-I levels were inversely correlated with ferritin levels (R = -0.328, p < 0.05).
Inferred Conclusions
Serum ferritin is a potential predictor of ME/CFS development in long COVID patients, particularly in women.
Elevated ferritin may reflect underlying inflammation or immune dysregulation associated with ME/CFS pathogenesis.
Endocrine abnormalities (altered growth hormone and IGF-I axes) accompany elevated ferritin in ME/CFS patients.
Remaining Questions
Does ferritin elevation represent a cause or consequence of ME/CFS development, and can ferritin levels be therapeutically modified to alter disease trajectory?
What is the optimal ferritin threshold for predicting ME/CFS, and how does this threshold differ across sex and demographic groups?
What This Study Does Not Prove
This study demonstrates correlation between elevated ferritin and ME/CFS development but does not establish causation—ferritin elevation may be a consequence rather than a driver of ME/CFS pathology. The observational design prevents determination of whether ferritin itself plays a mechanistic role or merely serves as a marker of underlying inflammatory processes. Results require validation in prospective cohorts and are not generalizable beyond long COVID populations.