Complement System

The complement system consists of almost 60 proteins, approximately 30 of which are circulating blood proteins that work together to promote immune and inflammatory responses. Complement tests measure the amount or activity of complement proteins in the blood.

For the CHSO, the normal range is 50~100U/mL

Decreased complement activity may be seen with:

  • Recurrent microbial infections (usually bacterial)
  • Autoimmune diseases, including lupus and rheumatoid arthritis
  • Hereditary angioedema
  • Acquired angioedema
  • Various types of kidney disease, including glomerulonephritis, lupus nephritis, membranous nephritis, and IgA nephropathy as well as kidney transplant rejection
  • Cirrhosis
  • Hepatitis
  • Malnutrition
  • Septicemia, shock
  • Serum sickness (immune complex disease)

Increased complement activity may also be seen with:

  • Cancer (leukemia, Hodgkin lymphoma, sarcoma)
  • Ulcerative colitis
  • Thyroiditis
  • Acute myocardial infarction
  • Sarcoidosis
  • Juvenile rheumatoid arthritis
* The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.