In healthy subjects, from 50 to 80 % of the serum ferritin is glycosylated [1, 2] . A decrease in the percentage of ferritin glycosylation can be observed in inflammatory diseases, malignancies, infections, or liver disease but is rarely less than 20% [3 , 4] . Percentage of glycosylated ferritin below 20% have been described in patients with adult Still's disease and haemophagocytosis lymphohistiocytic syndromes (HLH).