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HelpTest Code C4 or LAB151 C4 Complement, Serum or Plasma
Specimen Requirements
| Container Type: |
Optimal: Gold or Mint* *For STAT requests |
|
Acceptable: Red or Green |
|
| Optimal Collection Volume: |
4.5mL; full tube |
| Minimum Volume: |
|
| Collection Instructions: |
Gently invert the sample 5-6 times after collection. |
| Specimen Transport: |
Refrigerate |
| Processing Instructions: |
1. If serum, allow the specimen to clot for 30 minutes. 2. Centrifuge specimen within 2 hours of collection. 3. After centrifugation, specimen tubes without a gel barrier should have the serum or plasma aliquoted to a false bottom container. 4. Keep the serum or plasma refrigerated until testing can be performed. |
Specimen Stability
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum* | Refrigerated | 8 days |
| Room Temperature | 2 days |
*Note: Heparinized plasma in gel separator tubes is less stable than serum and is only suitable for add-on testing up to 2 days following sample collection.
Specimen Rejection Criteria
| Hemolysis | Mild OK; Moderate OK; Gross Reject |
| Lipemia | Mild OK; Moderate OK; Gross Reject |
| Icterus | Mild OK; Moderate OK; Gross Reject |
| Other | Quantity not sufficient |
Useful For
The main use of C4 determinations is assessing the course of hypocomplement conditions. As an acute phase protein, C4 is produced to an increased extent during inflammatory processes. It is elevated in systemic infections, non-infectious chronic inflammatory conditions (primarily chronic polyarthritis), and physiological states (pregnancy). The elevation rarely exceeds twice the normal value and can mask a reduction in the current consumption.
Methodology
Roche Cobas - Immunoturbidimetric
Reference Ranges
10-40 mg/dL
Interpretive
C4 levels will be decreased in acquired autoimmune disorders, in the active phase of lupus erythematosus, and in rheumatoid arthritis.
An undetectable C4 level (with normal C3) suggests a congenital C4 deficiency.
Levels will be increased in patients with autoimmune hemolytic anemia.
Source: Mayo Medical Labs
Day(s) Performed
24/7
Expected TAT
Same day
Performing Laboratory
Bronson Laboratory, Chemistry - Kalamazoo
Sample Retention Time
7 days
CPT Code
86160
LOINC Code
4498-2