Evaluation of hyperferritinemia causes in rheumatology practice: a retrospective, single-center experience

Hyperferritinemia may develop due to various reasons such as inflammation, infection, or malignancy. The purpose of the study to explore the prevalence and to figure out the causes of general hyperferritinemia and extreme hyperferritinemia as detected through the ferritin measurements requested by the rheumatology department. Adult patients at the age of 18 years and older with at least one serum ferritin level measurement at or above 500 ng/mL as requested by the rheumatology department between January 2010 and December 2019 were evaluated retrospectively. Hyperferritinemia was detected in 4.7% of 11,498 serum ferritin tests. The mean age of 242 patients found to have hyperferritinemia was 53.7 ± 17.1 years; of the patients, 63.2% were female, and the mean serum ferritin value was 2820 ± 5080 ng/mL. The most common cause of hyperferritinemia was rheumatological diseases with a ratio of 59.1%, which was followed by infections, iron overload, and solid malignancy. Among the rheumatologic diseases, adult-onset Still’s disease (AOSD), rheumatoid arthritis, and vasculitis were the cause accounting for hyperferritinemia. Ferritin levels were significantly higher in the AOSD group compared to the other rheumatologic disease groups (p < 0.0001). While extreme hyperferritinemia (ferritin ≥ 10,000 ng/mL) rate in our cohort was 0.2%, the most common cause was AOSD (15/17). In patients with hyperferritinemia, 3 month mortality was found to be 8.7%. CRP level was identified as the only independent predictor for the 3 month mortality in all patients [OR 1.088 (95% CI 1.004–1.178), p = 0.039]. Although rheumatologic disease activation and infections are the most common causes, the other causes should also be considered for the differential diagnosis.