C3 and chronic kidney disease: The sensitivity and specificity rates for anti-dsDNA and C3 levels in distinguishing between active LN and quiescent disease in this study were similar to results published by independent investigators (52, 53), whereas CD44 was more sensitive and specific in distinguishing active LN from quiescent LN, active non-renal SLE and CKD, thereby demonstrating kidney specificity in SLE patients, and measuring serum CD44 level could assist in the diagnosis of active LN.