Hematologic manifestations of juvenile systemic lupus erythematosus: An emphasis on anemia.

OBJECTIVE: Anemia is common in patients with juvenile systemic lupus erythematosus (jSLE). While autoimmune hemolytic anemia (AIHA) is the only etiology included in the classification criteria, the etiology of anemia in jSLE may be diverse. We aimed to investigate the etiology of anemia in jSLE and the relationship between anemia and disease characteristics at onset and during the follow-up period. METHODS: Patients diagnosed with jSLE who met the Systemic Lupus Erythematosus International Collaborating Clinics classification criteria between January 2012 and December 2020 were retrospectively analyzed. RESULTS: Hematologic involvement was observed in 70% of the patients. Anemia was the most common cytopenia among patients (60%). Anemia of chronic disease (ACD) and AIHA were the most common etiological factors, both observed in 23% of patients. Patients with anemia had a significantly higher rate of positive ds-DNA antibody and higher erythrocyte sedimentation rate (ESH) and Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) scores. ESH, serum ferritin, and SLEDAI scores negatively correlated with hemoglobin levels in patients with anemia. Iron deficiency was the sole etiology of new-onset anemia. Patients with new-onset anemia during the follow-up period had significantly lower hemoglobin values at onset and a higher rate of renal involvement. CONCLUSION: Anemia in jSLE is mostly AIHA and ACD, but iron deficiency is not rare. The severity of inflammation is associated with the severity of anemia. During the follow-up period, iron deficiency was the predominant cause of anemia, especially in patients with lower hemoglobin concentrations at onset and renal involvement.