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Complement, Total (C3+C4)

Test ID:

704802

CPT code:

86162

Synonyms:

Complement, Total (CH50)

CH50

Total Hemolytic Complement

Clinical Use:

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.

Test Information:

Complement is a system of 25 cell membrane associated and plasma proteins, which when activated produce multiple inflammatory mediators, opsonins, lysins, and down regulators vital to the normal function of the immune system. Complement components belong to a “classical” and “alternative” pathway whose activation steps differ. Complement proteins can be increased as part of the acute-phase response to inflammation or infection, and they can be decreased or absent due to hypercatabolism, expenditure in immune complexes, or hereditary deficiency. Patients with hereditary absence of a complement protein may have decreased total complement and recurrent bacterial infections or a rheumatic illness. Conversely, patients with rheumatic diseases, particularly with active illness and activation of complement and formation of immune complexes, may have low total complement. Falling complement levels may presage clinical flares, particularly of lupus nephritis.

Specimen Type:

Serum, frozen

Requested Volume:

1 mL

Minimum Volume:

0.5 mL

Container Type:

Red-top tube or gel-barrier tube

Collection:

Allow specimen to clot at room temperature for 15 to 30 minutes. Remove serum after centrifugation, place in plastic transport tube and freeze. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.