Complement, Total (CH50)
This test is used to measure the levels of all Total Complement. CH50 can be used to assess the integrity of the classical pathway of the immune system.
A normal CH50 level indicates that all the components of the C1 through C9 are present; however, even in the presence of a normal CH50, the absolute levels of some complement components (eg, C3 or C4) can be significantly (50% to 80%) lower than normal without affecting CH50 activity. This is because normal serum contains C3 and C4 in substantial excess of that required to yield a normal result for CH50. Depletion of alternative factors is not detected. For this reason, it may be necessary to measure individual complement components.
The most common use of CH50 is to Evaluate and follow up SLE (systemic lupus erythematosus) patient's response to therapy; may predict disease flare in SLE; evaluate for complement component deficiency; evaluate complement activity in cases of immune complex disease, glomerulonephritis, rheumatoid arthritis, SBE, cryoglobulinemia. The CH50 assay mainly evaluates the classical pathway.