Since we do not have a biological test available to diagnose sJIA or AOSD, the clinician must diagnose by excluding other diseases with similar symptoms, based on the anamnesis data, clinical signs and the following biological parameters: blood count, increased ESR and CRP, elevated serum ferritin levels, elevated levels of interleukin 1 (IL-1) and IL-6. Here, IL6 is linked to adult-onset Still disease.