Serum ferritin and isoferritins are tools for diagnosis of active adult Still's disease
Still's disease is an acute systemic inflammatory disorder. There are no pathognomonic symptoms or specific laboratory abnormalities. Serum ferritin concentration in rheumatoid arthritis together with some plasma glycoproteins such as alpha 2-glycoprotein and C-reactive protein are part of the response to inflammation. Ferritin in plasma is glycosylated and the sialoglycosylated forms increase its microheterogeneity. Our purpose was to confirm in a large series that high values of ferritin can be found in adult Still's disease (ASD) and to see if a specific isoferritin can be isolated in this disease compared with the other systemic diseases. Thirty-one sera were investigated from 11 men and 9 women with ASD and compared with 27 sera from 27 patients with systemic diseases. We studied the course of one case of ASD for 15 months. Serum ferritin was determined by immunoenzymology (Abbott Ferrizin). The isoferritins were investigated by isoelectric focussing and the percentage of glycosylation by affinity for concanavalin A (Con-A). In patients with active ASD, the ferritin levels were higher than in patients with inactive ASD or other systemic diseases: p < 0.001. The glycoforms of ferritin were basic and the proportion of ferritin bound to Con-A was lower than other ASD: p < 0.001. Serum ferritin levels have a diagnostic value for acute ASD. The study of sialylation and abnormalities in the glycosylation of ferritin helps to discriminate ASD from arthritis or other systemic diseases. In conclusion, the glycoform of isoferritins and the percentage of glycosylation offers an additional tool for the diagnosis of Still's disease.