Test Details
Methodology
Immunologic
Result Turnaround Time
1 - 2 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Use
Quantitation of C3 is used to detect individuals with inborn deficiency of this factor or those with immunologic disease in whom complement is consumed at an increased rate. These include lupus erythematosus, chronic active hepatitis, certain chronic infections, poststreptococcal and membranoproliferative glomerulonephritis, and others.
Limitations
Detects both biologically active and inactive C3
Custom Additional Information
C3 comprises about 70% of the total protein in the complement system and is central to activation of both the classical and alternate pathways. Increased levels are found in numerous inflammatory states as an acute phase response. CH50 (total complement hemolytic activity), C3 and/or C4 may be decreased in cases of systemic lupus erythematosus, especially in cases with lupus nephritis, acute and chronic hypocomplementemic nephritis, subacute bacterial endocarditis, DIC, and partial lipodystrophy (with associated nephritis-like activity in serum.) In cases of disseminated intravascular coagulation, plasmin attacks C3 directly, and C3 levels have been found low in the hemolytic uremic syndrome form of disseminated intravascular coagulation (DIC). Cases of hereditary C3 deficiency, while rare, have been reported and are characterized clinically by recurrent infections (eg, pneumonia, meningitis, paronychia, impetigo). Pathogenic bacteria causing infections in these cases have included both gram-positive and gram-negative organisms. C3 levels have also been found deficient in cases of uremia, chronic liver diseases, anorexia nervosa, and celiac disease.
Specimen Requirements
Specimen
Serum (preferred) or plasma
Volume
1 mL (adult), 0.5 mL (pediatric)
Container
Red-top tube, gel-barrier tube, or green-top (heparin) tube.
Collection Instructions
Remove serum or plasma within 45 minutes and transfer to a plastic transport tube.
Stability Requirements
Temperature | Period |
|---|---|
Room temperature | 4 days |
Refrigerated | 8 days |
Frozen | 8 days |
Freeze/thaw cycles | Stable x1 |
Reference Range
See table.
Age (d) | Male (mg/dL) | Female (mg/dL) |
|---|---|---|
0 to 14 | 50−121 | 50−121 |
15 to 30 | 51−160 | 51−160 |
>30 | 82−167 | 82−167 |
Storage Instructions
Refrigerate.
Causes for Rejection
Excessive lipemia (>1500 mg/dL) significantly increases the apparent C3 concentration.
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 006452 | Complement C3, Serum | 4485-9 | 006453 | Complement C3, Serum | mg/dL | 4485-9 |
| Order Code | 006452 | |||||
| Order Code Name | Complement C3, Serum | |||||
| Order Loinc | 4485-9 | |||||
| Result Code | 006453 | |||||
| Result Code Name | Complement C3, Serum | |||||
| UofM | mg/dL | |||||
| Result LOINC | 4485-9 |