Diagnostic value of serum ferritin in systemic onset juvenile idiopathic arthritis

Lei YIN; Wei ZHOU; Yanliang JIN; Huaiyuan LI; Hua SUN; Zhengyu ZHOU

ABSTRACT

Objective To investigate the diagnostic value of serum ferritin in children with systemic onset juvenile idiopathic arthritis (SO-JIA). Methods Fifty-seven patients with fever of unknown origin (rectal temperature>38.5 ℃ ) over two weeks and hospitalized in our general medicine ward longer than one week were enrolled in this study. Patients were recorded the course of fever, elinieal symptoms and signs including rash and swollen joints/arthralgia, laboratory tests including complete blood cell count, C-reactive protein, erythroeyte sedimentation rate, lactate dehydrogenase and the level of serum ferritin. SPSS 10.0 was used for statistical analysis. Results Two of 57 patients could not be diagnosed before discharge. The other 55 patients whose diagnosis was confirmed were divided into four groups. Twenty-five patients were SO-JIA,12 patients had hematologic or oncological diseases, 12 patients had infectious diseases and 6 patients had other rheumatic diseases. The level of serum ferritin was significantly higher (P<0.01) in SO-JIA group than in other groups. Moreover, the levels of serum ferritin in SO-JIA group were all higher than normal and the levels of serum ferritin in 76% of SO-JIA group were more than five-fold elevation. Four cut-off levels of serum ferritin level for the diagnosis of SO-JIA were selected based on clinical practice and ROC curve. When the cut-off levels of serum ferritin were 328.25, 529.50, 731.05 ng/ml and 1121.10 ng/ml, the sensitivity for the diagnosis were 100%, 88%, 72%, and 64% respectively, the specificity were 77%, 87%, 90% and 100%,respectively. Conclusion Serum ferritin is valuable for the diagnosis of SO-JIA and 529.50 ng/ml may be a good cut-off level