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). The glycosylated ferritin has been included in the diagnostic criteria for Still's disease in adults. A cut-off of less than 20 % has a sensitivity and specificity of 72 and 69 % respectively , and 35 and 94 % when combined with a total ferritin level greater than 5 times normal value. This parameter was also suggested to be a more specific marker to confirm a diagnosis of HLH than a high ferritin level ( \> 500μg / L). However, several limitations of this parameter were highlighted, some conditions making its interpretation difficult : particularly in cases of major hepatic cytolysis and severe sepsis (miliary tuberculosis, lymphoma and disease Adult Still). It is not always possible to distinguish severe sepsis, HLH syndrome and Still's disease. A fine analysis of various glycoforms components of ferritin could be used to distinguish different subgroups of patients. Few data are available on the mechanism of secretion and glycosylation of ferritin, but the investigators assume that the glycosylation patterns of ferritin may vary between different disease states and reflect distinct underlying pathophysiological mechanisms.