Clinical Information

Total Complement (CH50) is a functional assay that measures the activity of complement components C1 to C9 (i.e., the classical and terminal pathways). It does not measure the functional activity of the alternative pathway. If the Total Complement (CH50) measurement is zero or very low it is advisable to repeat the test to confirm the result. If the result is confirmed, the clinical presentation should be considered prior to further testing. If the patient exhibits recurrent neisserial infection, immunochemical determination of C5, C6, C7 and C8 is advised (or a functional assay for C5-C8). If the clinical problem is angioedema, initial studies should include C3, C4, C1 inhibitor (and possibly C1q and C2). Acquired disorders such as immune-mediated glomerulonephritis and other autoimmune disorders should direct testing towards C3 and C4.