Variations in the levels of two proteins — ferritin and fibrinogen — at the time of a systemic juvenile idiopathic arthritis diagnosis may be early warning signs of macrophage activation syndrome (MAS), according to a recent study.
Physicians should be on the lookout for these indicators of imminent MAS, a potentially life-threatening condition characterized by severe inflammation, the researchers said.
The study, “The frequency of macrophage activation syndrome and disease course in systemic juvenile idiopathic arthritis,” was published in Modern Rheumatology.
Systemic juvenile idiopathic arthritis (sJIA) is the most severe type of juvenile arthritis (JIA) and is characterized by widespread tissue inflammation that not only affects patients’ joints, but also organs and glands.
A possible complication of sJIA is macrophage activation syndrome (MAS), observed in 10-25% of cases.
MAS, a condition caused by the overactivation of a type of immune cells called macrophages, is characterized by unremitting fever, liver and spleen enlargement, abnormal bleeding, central nervous system dysfunction. and multiple organ failure.
In this study, researchers set out to determine the incidence of MAS in children with sJIA and identify potential indicators of the disease in these patients. The also sought to assess the impact of MAS on the course of the sJIA in the long run.
The observational study involved a total 53 children with sJIA who had been followed at the Clinic of Pediatric Rheumatology in the Kanuni Sultan Süleyman Research and Training Hospital in Turkey between May 2010 and September 2017.
Over the course of an average follow-up period of 39 months (3.25 years), approximately one-third of the children (33.9%) developed MAS.
After comparing lab tests that had been performed when children had been diagnosed with sJIA, researchers found that only the levels of ferritin and fibrinogen were significantly different between children who developed MAS later on and those who did not. Ferritin is a protein responsible for storing iron in the body, while fibrinogen is a protein that is necessary for blood clotting.
More specifically, the researchers discovered that at the time of diagnosis, the children who would later develop MAS had higher ferritin levels (4,482 mg/dl versus 2,060 mg/dl) and lower fibrinogen levels (371 mg/dl versus 466 mg/dl) than those who did not developed the condition during the study period.
“All sJIA patients should be followed for the development of MAS. Higher ferritin and relatively lower fibrinogen levels at the time of diagnosis of sJIA may be early warning signs of impending
MAS,” the researchers said.
Long-term follow-up analyses revealed that 45.2% of the children had a monocyclic disease course — or disease with extended periods of remission — while 30.1% had a polyciclic disease course, meaning disease with recurring flare-ups of symptoms. The other 24.5% were found to have a persistent disease course, with constant presence of symptoms, or active disease.
Children who developed MAS during the study were equally distributed among these three groups.
“sJIA patients that develop MAS do not seem to warrant more guarded prognosis in the long term followup and sJIA patients that follow a persistent course are possibly one of the hardest group of patients to treat in pediatric rheumatology,” the researchers said.