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HelpTest Code COMC50 Complement, Total, Serum
Additional Codes
| Mayo Test ID |
|---|
| COM |
Reporting Name
Complement, Total, SUseful For
Detection of individuals with an ongoing immune process
First-tier screening test for congenital complement deficiencies
Method Name
Automated Liposome Lysis Assay
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Serum RedSpecimen Required
Patient Preparation: Fasting preferred.
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube: Red top (serum gel/SST are not acceptable)
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions:
1. Immediately after specimen collection, place the tube on wet ice.
2. After sample has clotted on wet ice, centrifuge at 4° C and aliquot serum into 5 mL plastic vial.
3. Within 30 minutes of centrifugation, freeze specimen. Sample must be placed on dry ice if not frozen immediately.
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum Red | Frozen | 28 days |
Reject Due To
| Gross hemolysis | OK |
| Gross lipemia | OK |
| Gross icterus | OK |
Reference Values
30-75 U/mL
Day(s) Performed
Monday through Friday
CPT Code Information
86162
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| COM | Complement, Total, S | 4532-8 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| COM | Complement, Total, S | 4532-8 |
Clinical Information
Complement (C) proteins are components of the innate immune system. There are 3 pathways to complement activation: the classical pathway, the alternative (or properdin) pathway, and the lectin (or mannan-binding lectin) pathway. The classical pathway of the complement system is composed of a series of proteins that are activated in response to the presence of immune complexes. A single IgM molecule or two IgG molecules are sufficient to trigger activation of the recognition complex initiated by C1q. The activation process triggers a cascade that includes an amplification loop. The amplification loop is mediated by C3, with cleavage of a series of proteins, and results in three main end products: anaphylatoxins which promote inflammation (C3a, C5a); opsonization peptides that are chemotactic for neutrophils (C3b) and facilitate phagocytosis; and the membrane attack complex (MAC), which promotes cell lysis.
The absence of early components (C1, C2, C3, C4) of the complement cascade results in the inability of immune complexes to activate the cascade. Patients with deficiencies of the early complement proteins are unable to generate the peptides that are necessary to clear immune complexes and to attract neutrophils or to generate lytic activity. These patients have increased susceptibility to infections with encapsulated microorganisms. They may also have symptoms that suggest autoimmune disease; complement deficiency may be an etiologic factor in the development of autoimmune disease.
Patients with deficiencies of the late complement proteins (C5, C6, C7, C8, and C9) are unable to form the MAC and may have increased susceptibility to neisserial infections.
Undetectable complement levels are found in patients with specific component deficiencies. Decreased complement levels are found in infectious and autoimmune diseases due to fixation and consumption of complement.
Interpretation
Low levels of total complement (total hemolytic complement) may occur during infections, disease exacerbation in patients with systemic lupus erythematosus, and in patients with immune complex diseases such as glomerulonephritis.
Undetectable levels suggest the possibility of a complement component deficiency. Individual complement component assays are useful to identify the specific deficiency.
Cautions
Because this is a functional assay, the results are dependent on appropriate specimen transport and storage.
Method Description
An automated method is performed using liposomes as the target for the serum complement system. Dinitrophenyl (DNP)-labeled liposomes are sensitized with antibody to DNP. Serum complement causes lysis and release of entrapped glucose-6-phosphate dehydrogenase. Glucose-6-phosphate dehydrogenase reacts with glucose-6-phosphate and nicotinamide adenine dinucleotide (NAD[+]). NAD(+) is then reduced to NADH, and the conversion is measured at 340 nm. The assay correlates with the total complement assay based on sheep red blood cell lysis, has lower variability, and is simpler to perform.(Package insert: Fujifilm Autokit CH50. Fujifilm Wako Pure Chemical Corporation; 04/2018; Yamamoto S, Kubotsu K, Kida M, et al. Automated homogeneous liposome-based assay system for total complement activity. Clin Chem. 1995;41(4):586-590)