AbstractThe diagnostic and prognostic utility of extremely elevated ferritin values in hospitalized medical patients is lacking. We aimed to determine the clinical significance of ferritin levels ≥ 1000 ng/mL in adults hospitalized in the general medical service. We scanned the hospital laboratory database for ferritin values ≥ 1000 ng/mL, and evaluated the medical history, diagnoses, and survival of patients hospitalized in the general medical service. We compared the characteristics and outcomes of patients with values up-to versus above 2,999 ng/mL. Ferritin samples ranging from 1,003 to 12,170 ng/mL from 422 patients in the lower and 94 in the higher ferritin groups were included. Malignancy, repeat blood transfusions and recent chemotherapy were more prevalent in the higher ferritin group (p=0.003, p=0.002, and p<0.001, respectively). Infection (58.7%), chronic kidney disease (22.0%), and solid or hematological malignancies (21.6% and 17.1%, respectively) were the leading conditions associated with elevated ferritin. One-year survival was low, and significantly lower in patients in the higher ferritin group (10.8% vs. 16.9%, p=0.004). In conclusion, extremely elevated ferritin values in patients admitted to the general medical service are associated with multiplicity of clinical conditions and poor outcome.