CH50 (Complement, Total) Test

The complement system helps or “complements” augmenting the ability of phagocytes or antibodies to help fight against infections and agents that the body classifies as foreign, “antigen”. It belongs to the immune system and comprises of proteins that are produced in the liver.

However, when the body attacks these “antigens” it creates harm to it’s own tissues, and hence the concentration of this complement should be tightly controlled. Thus, the proteins which control the level of this complement are always present in a higher amount than the proteins themselves.

Reference Values

Reference range depends on age and medical history. Normal range may vary between 31-60 U/mL

Interpretations

Decreased complement levels may be seen with

Recurrent microbial infections (Hereditary complement deficiency predisposes to infections),
Autoimmune diseases (Decreased complement levels are due to increased consumption in autoimmune diseases)
Hereditary angioedema (inflammation and swelling)
Various types of kidney diseases, Serum sickness etc

Increased complement levels are seen during acute or chronic (lasting for a long time usually 6 months or more) inflammation, where high levels are consistently present in order to initiate an immune response.