Turbidimetry system

Anti-dsDNA levels were determined in serum using Unicap Elia (Phadia Laboratory Systems, Uppsala, Sweden). Levels of complement C3 in serum and plasma IgG, IgM, and IgA were determined using the Nephelometry System (Beckman Coulter). Albumin/creatinine was determined in serum by the turbidimetry system (Abbott, Chicago, USA). The presence of hematuria was determined by the Combur test (Roche, Basilea, Switzerland). Anti-dsDNA antibodies were considered positive when levels were >17 UI/ml. Levels of albumin/creatinine were expressed as mg/mmol. Levels of complement C3 and immunoglobulins were expressed as mg/dl.

Anti-dsDNA, Sm, SSB-La, SSA-Ro and U1-RNP levels were determined in serum using BIO-FLASH® chemiluminescence (Werfen, Barcelona, Spain). Anti-C1q levels in serum were quantified by Quanta Lite Anti-C1q ELISA (Inova Diagnostic, San Diego, CA, USA). Anti-histone presence in serum was established using Euroline ANA Perfil (Euroimmune, Lübeck, Germany). Levels of C3 in serum were determined using the Nephelometry System (Beckman Coulter Diagnostics, Nyon, Switzerland). Albumin/creatinine ratio was determined in serum by the turbidimetry system (Abbott, Chicago, IL, USA). The presence of hematuria was determined by the Combur test (Roche, Basilea, Switzerland). Anti-dsDNA antibodies were considered positive when levels were >35 UI/mL. Sm, SSB-La, SSA-Ro and U1-RNP antibodies were considered positive when levels were >20 Chemoluminiscence Units and C1q when levels were >20 U/mL according to manufacturer’s study. C3 levels were considered decreased when they were below 85 mg/dL according to manufacturer’s study. Microalbuminuria was considered when albumin/creatinine ratio was >2.5 mg/mmol.