Assessment of an undetectable total complement (CH50) level
Diagnosing congenital C1 (first component of complement) deficiency
Diagnosing acquired deficiency of C1 inhibitor
Nephelometry
C1Q (Complement Component C1Q), Serum
Complement Component C1q
First Component of Complement
Serum
Patient Preparation: Fasting
Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Specimen Volume: 1 mL
0.5 mL
Gross hemolysis | OK |
Gross lipemia | Reject |
Gross icterus | OK |
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Serum | Refrigerated (preferred) | 28 days | |
Frozen | 28 days | ||
Ambient | 21 days |
Assessment of an undetectable total complement (CH50) level
Diagnosing congenital C1 (first component of complement) deficiency
Diagnosing acquired deficiency of C1 inhibitor
The first component of complement (C1) is composed of 3 subunits designated as C1q, C1r, and C1s. C1q recognizes and binds to immunoglobulin complexed to antigen and initiates the complement cascade. Congenital deficiencies of any of the early complement components (C1, C2, C4) results in an inability to clear immune complexes. Inherited deficiency of C1 is rare.
Like the more common C2 deficiency, C1 deficiency is associated with increased incidence of immune complex disease (systemic lupus erythematosus, polymyositis, glomerulonephritis, and Henoch-Schonlein purpura). Low C1 levels have also been reported in patients with abnormal immunoglobulin levels (Bruton and common variable hypogammaglobulinemia and severe combined immunodeficiency). This is most likely due to increased catabolism.
The measurement of C1q is an indicator of the amount of C1 present.
12-22 mg/dL
An undetectable C1q in the presence of an absent total complement (CH50) and
A low C1q in combination with a low C1 inhibitor and low C4
This is a different assay than C1q binding, which is an assay for
1. Frank MM: Complement in the pathophysiology of human disease.
2. Frank MM: Complement deficiencies. Pediatr Clin North Am
3. Frigas E: Angioedema with acquired deficiency of the C1 inhibitor:
Nephelometry and anti-C1q antiserum are used to quantitate the C1q antigen level.(Instruction manual: Nephelometer II Operations. Siemens, Inc., Newark, DE, 5/2005)
Monday through Friday
This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.
86160
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
C1Q | Complement C1q, S | 4478-4 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
C1Q | Complement C1q, S | 4478-4 |