Background/Purpose: Lupus nephritis (LN) is the major findings in systemic lupus erythematosus (SLE). LN with some pathologic findings in the kidney but had normal urine were called as silent LN (sLN); renal biopsy revealed that 70% of sLN patients were in Class I/II and 20% in Class III/IV in adult survey. However, there were few studies to examine sLN in juvenile SLE (JSLE). Therefore, clinical and renal pathologic findings in children with sLN were examined.

Methods: JSLE patients whose onset was before 16 years old, referred to our hospital from 2000 to 2011, were recruited in the study. Patients were divided into two groups according to urinary findings at the first examination; sLN and overt LN (oLN). Clinical findings such as gender, age at onset, ISN/RPS pathologic classification, general analysis of whole blood, and urinary findings after 3 years of therapy were retrospectively examined and compared between the two groups by using the Mann-Whitney U-test or the Fisher exact test.

Results: A total of 31 JSLE patients were involved in the study. Of the 31 patients, 18 (58%) were sLN and 13 (42%) were oLN. As to gender, the incidence of male was significantly higher in sLN group (33%) than oLN group (0%) (P = 0.028). Pathologic findings of ISN/RPS classification in sLN patients were Class I in 3, Class II in 12, and Class III in 3. In oLN patients, those were Class II in 3, Class III in 6, Class IV in 2, Class V in 1, and Class III + V in 1. Complement C3 level showed no statistical difference between the two groups. However, in sLN group, complement C3 levels in Class II (56 ± 23 mg/dL) and Class III (37 ± 19 mg/dL) were significantly lower than that observed in Class I (96 ± 26 mg/dL) (P = 0.02 and 0.04, respectively). Anti-dsDNA antibody titer showed no statistical difference between the two groups. On the other hand, anti-Sm antibody titer was significantly higher in sLN group (67 ± 54 U/mL) compared to oLN group (30 ± 49 U/mL) (P = 0.015). Urinary findings were still normal in 17/18 (94%) of sLN patients after 3 years of therapy.

Conclusion: In conclusion, these results suggest that complement C3 level and anti-Sm antibody may be a useful tool for predicting the severity and associated with the pathogenesis of sLN in JSLE, respectively. Though the all of the male patients were in sLN group, more than 90% of sLN patients maintained normal urinary findings at 3 years after initiating therapy. Considering the general concept that the prognosis of JSLE in male is more severe than that of female’s, the present study may indicate that the early therapeutic intervention from sLN stage is essential to prevent the progression of renal damage.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/clinical-features-of-children-with-silent-lupus-nephritis/