Low complement c3 indicates the presence of antigen-antibody reactions in the body, or autoimmune diseases, or decreased complement synthesis due to poor liver function. Normally, people are more prone to colds, dermatitis and other diseases than normal people. The main indicators of rheumatism identification are anti-o and c antiprotein, esr sedimentation, if these items are normal, you can exclude the possibility of rheumatism. Complement component consumption increases, such as serum sickness, glomerulonephritis after streptococcal infection, systemic sle, cryoglobulinemia, autoimmune hemolytic anemia, rheumatoid arthritis organ transplantation after the rejection reaction.