[ETIOLOGIES OF EXTREME HYPERFERRITINEMIA - ANALYSIS OF A LARGE DATABASE].

Besides its role in iron homeostasis and storage, ferritin is also regarded as an acute-phase reactant. Extreme Hyperferritinemia is seen in severe inflammatory conditions, severe infections, iron storage diseases and malignancies. A direct linkage between high ferritin levels and poor prognosis has been observed. To characterize patients with extreme high ferritin levels in the serum for possible etiologies and assessment of the correlation between ferritin levels, prognosis and mortality. We conducted a retrospective cohort study between the years 2002-2016 using the large database of Clalit Health Services. Patients older than 18 years with ferritin levels above 10,000 ng/ml that were taken during hospitalization and ambulatory visits were included in the study. After examining the medical files of each patient, we evaluated the demographic characteristics, etiologies, clinical presentation and relevant laboratory parameters. We calculated the proportion of this data and compared it to the general population by using chi square test. The incidence of extreme hyperferritinemia was statistically significant in patients with autoimmune and rheumatologic diseases in particular adult onset Still's disease compared to the general population. Among hospitalized patients, bacterial and viral infections were the leading cause in 62% of cases. In ambulatory patients, hyperferritinemia was mainly secondary to chronic blood transfusions in patients with hemoglobinopathies and poor compliance to iron chelators. Among 21 biopsies from involved organs including lymph nodes, bone marrow and liver, hemophagocytosis was only observed in 5 cases (6.8%). Extreme hyperferritinemia with values higher than 10,000 ng/ml can be attributed to many inflammatory autoimmune conditions.