Update Type: Specimen collection or handling and/or storage changed
Test Updated: 08/25/2021
Test Overview
Test Methodology


Test Usage

Follow lupus patient's response to therapy; screen for genetic complement component deficiency. Detection of deficiencies and decreased levels of serum complement as seen in renal disease (acute glomerulonephritis, membranoproliferative glomerulonephritis, renal allograft rejection), collagen disease (active systemic lupus erythematosus (SLE), 10% of patients with rheumatoid arthritis (RA), hemolytic anemia (paroxysmal cold hemoglobinuria), hypersensitivity and autoimmune diseases (acute serum sickness, acute vasculitis) as well as subacute bacterial endocarditis, mixed cryoglobulinemia, and advanced hepatic cirrhosis.

Reference Range *

41 - 95 U/mL

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Test Limitations

Levels are affected by patient's age, stage and activity of disease, treatment and genetic factors. A single normal result may be misleading; longitudinal studies are clinically more helpful.

Test Details
Days Set Up
Monday, Thursday
Analytic Time

8 hours

Soft Order Code
MiChart Code
Complement, Total (CH50)
  • CAE Total Complement
  • CH50
  • Functional Complement Assay
  • Total Active Complement
  • Total Hemolytic Complement
Chemical Pathology
Specimen Requirements
Collection Instructions

Collect specimen in a red top or SST tube. Allow the specimen to clot on ice for 30 to 60 minutes (65 minutes maximum). Centrifuge and aliquot serum into a plastic vial. Freeze immediately. If specimen processing equipment is not available, the patient should have the specimen collected at an MLabs Blood Drawing station.

Special Handling

Place on ice immediately or process according to Offsite Collection Instructions.

Normal Volume
1.0 mL serum
Minimum Volume
0.5 mL serum
Rejection Criteria
Specimen received at room temperature or refrigerated or not on ice, serum not separated from red cells within 65 minutes of collection, or serum aliquot refrigerated and not frozen immediately after collection.
Additional Information

Measures biologically active and functional classical complement pathway and the presence of inhibitor activity as a whole. Complement mediates immune reactions. Hypocomplementemia that accompanies some forms of renal disease may indicate immune utilization. Low serum complement levels occur in some patients with severe RA, and may indicate the development of vasculitis. Low levels tend to correlate with active immunologic diseases. Total hemolytic complement, C3, and C4 may be decreased in a variety of diverse clinical situations, in particular in cases in which immune complex activation has occurred. Such problems include cases of SLE, especially if there is nephritis. Hypercomplementemia may be seen as part of the acute phase reaction.

CPT Code
Fee Code