Treatable renal disease in children with silent lupus nephritis detected by baseline biopsy: association with serum C3 levels.

Lupus nephritis is identified in up to 75% of patients with juvenile systemic lupus erythematosus and may present with abnormal urinary findings (overt lupus nephritis) or be apparent only upon renal biopsy (silent lupus nephritis). We investigated whether serum complement levels correlate with renal pathology in pediatric patients with silent lupus nephritis. We performed baseline renal biopsy in 45 children diagnosed with juvenile systemic lupus erythematosus who were admitted to Kagoshima University Hospital between January 2000 and June 2015. Patients were classified as having overt or silent lupus nephritis based on urinary findings at renal biopsy. Silent lupus nephritis was identified in 55.5% (25/45) of cases. Of these, 6 (13.3%) were classified as class III nephritis, according to the International Society of Nephrology/Renal Pathology Society criteria. Decreased serum C3 levels were associated with the renal pathology classification for patients with silent but not with overt lupus nephritis. No differences in serum C4 levels were identified between cases of silent and overt lupus nephritis. Baseline renal biopsy is a critical component of the work-up of juvenile systemic lupus erythematosus as treatable renal pathology may be present in the absence of urinary signs. Serum C3 may be an important marker of the progression of silent lupus nephritis.