29 September 2020
Serum ferritin as a measure of iron overload
Published online 17 February 2010
Increasing numbers of patients with sickle-cell disease are receiving chronic blood transfusions to minimize disease-related complications. Left untreated, blood iron concentration can build up to toxic levels (iron overload), so patients commonly receive chelator drugs and have their iron levels closely monitored. Serum ferritin (SF) levels are widely used to monitor iron load; however, the reported relationship of SF to other iron-load measures varies among studies, raising questions about the validity of the biomarker.
To resolve this issue, an international research team, including one representative from Lebanon, compared SF against two other measures of iron load in 271 patients receiving chronic blood transfusions as part of two clinical trials for stroke prevention. SF levels were found to be nonlinear compared with the increasing iron load estimated from transfusion history and liver iron concentrations, and this disparity was most pronounced at intermediate SF levels (~1,500–2,500 ng/mL). SF levels were more reliable at the extremes, with low levels (<1,500 ng/mL) indicating a mostly acceptable iron load, and high levels (>3,000 ng/mL) indicating a significant iron load and an association with liver injury.
These results question the reliability of SF as an iron-load measure, particularly at intermediate levels, and highlight the need for other methods to monitor iron levels accurately in the blood.