Laboratory tests revealed cytopenia - anemia Hgb - 89.0 g/L with positive direct Coombs test and thrombocytopenia Plt - 72.0 x10^9/L; impaired renal function - GFR 79.9 ml/min/1.73; low complement levels - C3 0.25 g/L and C4 < 0.020 g/L; positive ANA 1:640, anti-ds DNA 191 U/ml and anti SS-A > 200 antibodies. Here, C3 is linked to anemia.