Serum complements and immunoglobulin profiles in systemic lupus erythematosus patients: An observational study at a teaching hospital

CONTEXT: Serum complement proteins and autoantibodies play an important role in the pathogenesis and diagnosis of systemic lupus erythematosus (SLE). Abnormalities in various immunoglobulin levels are described in patients of SLE. AIMS: To study the spectrum of clinical manifestations and measure the serum levels of complement C3, complement C4, autoantibodies and immunoglobulin G (IgG) in patients of SLE and compare with healthy controls. SETTINGS AND DESIGN: The present study is a prospective hospital-based observational study conducted between May 2014 and December 2018. STATISTICAL ANALYSIS USED: Unpaired t-test was used to compare the mean values between the SLE patients and healthy controls. MATERIAL AND METHODS: A total of 100 cases of SLE and 100 healthy controls were included in the study. The clinical data were retrieved. Serum antinuclear antibody, anti-ds DNA antibody, and anti-Smith antibody levels, and complements C3, C4 and IgG were measured. RESULTS: Arthritis (89%) and anaemia (65%) were two common clinical presentations. The low complement C3 levels and C4 were detected in 64 and 62% of the SLE patients. Serum IgG was increased in 41% of the patients. A reduced level of IgG was detected in 6% of the patients. CONCLUSION: Primary care physicians should be aware of the clinical and serological manifestations of SLE as early detection will reduce end-organ damage. Autoantibody testing and complement testing should be done in all suspected cases. This study showed a significantly reduced C3 and C4 and elevated IgG in many cases of SLE as compared to control. Hypogammaglobulinemia was also present in a minority of the cases.