Complement, Total (CH50)
| Complement, Total (CH50) | | | |
| Number | | 001941 |
| CPT | | 86162 |
| Synonyms | | CH50 ; Total Hemolytic Complement |
| Test Includes | | Quantitation of total functional serum complement |
| Specimen | | Serum, frozen |
| Volume | | 1 mL |
| Minimum Volume | | 0.5 mL |
| Container | | Red-top tube or gel-barrier tube |
| Collection | | Allow specimen to clot at room temperature for 15-30 minutes. Remove serum after centrifugation, place in plastic transport tube, and freeze immediately. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested. |
Storage Instructions | | Freeze at -20°C for up to one week, or -40°C
for up to one month. For longer storage, freeze at -
70°C or lower. |
| Causes for Rejection | | Specimen not frozen; plasma specimen (ascorbic acid, bilirubin, hemoglobin, and lipemic turbidity do not have a significant effect on the measurement) |
| Reference Interval | | 22-60 units/mL; synovial fluid levels are greater than one-third of serum levels in patients with nonimmune processes. |
| 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. |
| Methodology | | Quantitative liposome lysis by spectrophotometry |
| Additional 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. |
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