Extremely high serum ferritin levels as diagnostic tool in adult-onset Still's disease.

The diagnosis of adult-onset Still's disease (ASD) is difficult to establish due to the nonspecific clinical and laboratory findings. A markedly raised serum ferritin level is a typical finding, although it is not well understood why ferritin levels are extremely high in ASD. We discuss several possible explanations leading to the extremely high levels of ferritin.