Ferritin, fever, and frequent visits: Hyperferritinemic syndromes in the emergency department.

ABSTRACT

Fever of unknown origin (FUO) is defined as persistent fevers without an identifiable cause despite extensive medical workup. Emergency physicians caring for patients reporting a persistent, nonspecific, febrile illness should carefully consider potentially serious non-infectious causes of FUO. We present a case of a 35-year-old man who presented to the emergency department (ED) three times over a 10-day period for persistent febrile illness and was ultimately diagnosed with Adult-Onset Still's Disease (AOSD) after a serum ferritin level was found to be over 42,000 µg/L. AOSD, along with macrophage activation syndrome, catastrophic antiphospholipid syndrome, and septic shock comprise the four hyperferritinemic syndromes. These are potentially life-threatening febrile illnesses that characteristically present with elevated ferritin levels. In this article, we highlight the value of a serum ferritin level in the workup of a patient with prolonged febrile illness and its utility in facilitating early diagnosis and prompt treatment of hyperferritinemic syndromes in the ED.