Name |
Complement C3 and C4 |
Alternative name/Profile |
C34, CH50, Alternative Pathway, Classical Pathway, CH100, Mannose-binding Lectin Pathway (MBL), Systemic Lupus Erythematosus (SLE), glomerulonephritis, autoimmune disease, Hereditory Angioedema, cryoglobulinemia |
Department |
Immunology |
Investigation |
Turbidimetry (Roche Cobas c 303) |
Specimen type |
Clotted blood |
Sample type |
Serum |
Sample container & volume |
5ml Red. |
Frequency of analysis |
Daily, Monday to Friday |
Turnaround time |
4 days |
Availability |
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Notes |
Useful for:
- Investigating patients for congenital complement deficiencies.
- Assessing disease activity in patients with active Systemic Lupus Erythematosus (SLE), glomerulonephritis or autoimmune disease.
- Investigating Hereditory Angioedema (C4 only).
Clinical Information:
- Complement is a component of the innate immune system.
- Complement can be activated by three pathways; the Classical Pathway, the Alternative Pathway and the Mannose-binding Lectin (MBL) Pathway.
- The Classical Pathway is activated via immune complexes while the Alternative Pathway is activated by bacterial polysaccharides.
- C4 is a key component of the Classical Pathway.
- All three pathways lead to the activation of C3 and C5. This activation causes C3a to be cleaved into C3b, resulting in the formation of the Membrane Attack Complex (MAC) of the Terminal Pathway; capable of inducing cell death.
- Decreased complement activation can be caused by a congenital complement deficiency or by an acquired complement deficiency.
- Patients that have a homozygous C3 deficiency have an increased susceptability to severe recurrent bacterial infections and may display symptoms of autoimmune disease.
- Reduced levels of C3 may be due to acute glomerulonephritis, membranoproliferative glomerulonephritis, autoimmune disease, active Systemic Lupus Erythematosis (SLE), septic shock or liver disease.
- A congenital C4 deficiency results in an inability to clear immune complexes.
- Reduced levels of C4 can be due to Systemic Lupus Erythematosus (SLE), glomerulonephritis, autoimmune disease, cryoglobulinemia, hereditary angioedema.
- Increased levels of C4 can be seen in autoimmune haemolytic anaemia.
Please Note:
- Where External Institiutions cannot guarantee immediate delivery, samples must be centrifuged, separated and stored at 4oC. Samples can then be transported, as soon as possible, to St. James's Hospital for processing.
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Related links |
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Reference range |
C3: 0.83 - 1.8g/L
C4: 0.14 - 0.54g/L
C3 reference ranges validated in-house 2009.
C4 Reference Ranges sourced from the Protein Reference Unit, Sheffield and last updated 2007.
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Last updated |
Mon, 23 Sep 2024 08:16:11 IST |
