Test Background The CH50 assay measures the ability of serum complement components to form membrane attack complex, which can be detected by ELISA. C3 and C4 levels must also be requested. The assay is used as a screening test for defects of individual components of the classical and terminal pathways. It should not be used for monitoring complement consumption, instead request C3 and C4 levels.
Clinical Indications Suspected complement deficiency Recurrent infections
Reference Range 50-125 % of normal
Sample Required RST (rust top) Separate and freeze immediately Transport frozen
Sample Volume 5-10 mL (1 mL serum)
Turnaround Time 21 days