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HelpTest Code AHUSD Atypical Hemolytic Uremic Syndrome Complement Panel, Serum and Plasma
Useful For
Detecting deficiencies in the alternative pathway that can cause atypical-hemolytic uremic syndrome, dense deposit disease, and C3 glomerulonephritis
A second-tier test that aids in the differential diagnosis of thrombotic microangiopathies
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| INTGA | AHUS Interpretation | No | Yes |
| COM3 | Complement, Total, S | Yes, (order COM) | Yes |
| AH503 | Alternative Complement Path Func, S | Yes, (order AH50) | Yes |
| C3HUS | Complement C3, S | Yes, (order C3) | Yes |
| C4HUS | Complement C4, S | Yes, (order C4) | Yes |
| FBCA | Factor B Complement Antigen, S | No | Yes |
| FHCA | Factor H Complement Antigen, S | No | Yes |
| C4D | C4d Complement, P | No | Yes |
| CBB | CBb Complement, P | No | Yes |
| SC5B9 | SC5b-9 Complement, P | Yes, (C5B9) | Yes |
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| C1Q | Complement C1q, S | Yes | No |
| C1QFX | C1Q Complement, Functional, S | Yes | No |
| C2FXN | C2 Complement, Functional, S, NR | Yes | No |
| C3FX | C3 Complement, Functional, S | Yes | No |
| C4FX | C4 Complement, Functional, S | Yes | No |
| C5FX | C5 Complement, Functional, S | Yes | No |
| C6FX | C6 Complement, Functional, S | Yes | No |
| C7FX | C7 Complement, Functional, S | Yes | No |
| C8FX | C8 Complement, Functional, S | Yes | No |
| C9FX | C9 Complement, Functional, S | Yes | No |
| C5AG2 | C5 Complement, Antigen, S | Yes, (order C5AG) | No |
Method Name
C3HUS, C4HUS, FBCA, FHCA: Nephelometry
COM3: Automated Liposome Lysis Assay
AH503, C4D, CBB, SC5B9: Enzyme-Linked Immunosorbent Assay (ELISA)
Reporting Name
aHUS Complement Panel, S and PSpecimen Type
Plasma Na CitSerum Red
Ordering Guidance
This test should be performed prior to treatment initiation and in the absence of therapy with complement inhibitors, such as eculizumab or ravulizumab. Complement inhibitors will affect performance of these assays.
For evaluating patients with possible thrombotic microangiopathies (TMA), the recommended first-tier test is ADM13 / ADAMTS13 Activity and Inhibitor Profile, Plasma. This test should be a second-tier test for TMA.
For patients who have received eculizumab or need to monitor response to eculizumab therapy, the recommended test is ECUMP / Eculizumab Monitoring Panel, Serum. Soluble membrane attack complex (sMAC) should not be used as a standalone assay to monitor eculizumab efficiency.
Specimen Required
Both plasma and serum are required for this test.
Patient Preparation:
1. Fasting preferred.
2. Samples should not be collected earlier than 48 hours following plasma exchange.
Supplies: Sarstedt Aliquot Tube 5 mL (T914)
Specimen Type: Plasma
Collection Container/Tube: Light-blue top (3.2% sodium citrate)
Submission Container/Tube: 3 plastic vials
Specimen Volume: 1.5 mL in 3 plastic vials, each containing 0.5 mL
Collection Instructions:
1. Immediately after specimen collection, place the tube on wet ice.
2. Centrifuge; 1500 x g for 10 minutes at 4° C and aliquot plasma into plastic vial.
3. Freeze specimen within 30 minutes.
Specimen Type: Serum
Collection Container/Tube: Red top (serum gel/SST are not acceptable)
Submission Container/Tube: 3 plastic vials
Specimen Volume: 1.5 mL in 3 plastic vials, each containing 0.5 mL
Collection Instructions:
1. Immediately after specimen collection, place the tube on wet ice.
2. Centrifuge at 4° C and aliquot serum into 5 mL plastic vial.
3. Freeze specimen within 30 minutes.
Specimen Minimum Volume
Serum, Plasma: 1 mL each
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Plasma Na Cit | Frozen | 14 days | |
| Serum Red | Frozen | 14 days |
Reject Due To
| Gross hemolysis | OK |
| Gross lipemia | Reject |
| Gross icterus | OK |
Clinical Information
Individuals presenting with thrombotic microangiopathies (TMA) require clinical testing to identify the underlying cause. Thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS) are both acute syndromes with many overlapping clinical features. Reduced levels of ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 motives, member 13) activity is associated with TTP and is one laboratory feature that distinguishes TTP from HUS. HUS can also have a number of causes; one of the rarer forms of disease is caused by defects in the alternative pathway of the complement system, so called atypical-HUS (aHUS). Patients with defective alternative pathway regulation can benefit from biologics that suppress the complement system.
The purpose of this panel is to aid in the differential diagnosis of TMA. The suggested approach is to rule-out other causes of TMA first, since aHUS is one of the rarer causes of TMA. Additionally, the assays can be used in the setting of membranoproliferative glomerulonephritis (MPGN) and can help distinguish between immune-complex mediated or complement-mediated kidney disease. MPGN mediated by immune-complexes are ones resulting from infectious processes, autoimmune diseases, or monoclonal gammopathies; whereas complement-mediated MPGN can be subdivided in C3 glomerulonephritis and dense deposit disease, based on electron microscopy of the kidney biopsy histological findings. Despite phenotypic differences, these glomerular diseases share dysfunction of the alternative pathway as the defining pathophysiology.
Reference Values
FACTOR B COMPLEMENT ANTIGEN
15.2-42.3 mg/dL
SC5b-9 COMPLEMENT
≤250 ng/mL
FACTOR H COMPLEMENT ANTIGEN
18.5 to 40.8 mg/dL
C4d COMPLEMENT ACTIVATION FRAGMENT
≤9.8 mcg/mL
CBb COMPLEMENT ACTIVATION FRAGMENT
≤1.6 mcg/mL
COMPLEMENT C4
14-40 mg/dL
COMPLEMENT C3
75-175 mg/dL
ALTERNATIVE COMPLEMENT, PATHWAY (AH50) FUNCTIONAL
≥46% normal
COMPLEMENT, TOTAL
30-75 U/mL
Day(s) Performed
Varies
Report Available
12 to 21 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
86160 x 7
86161
86162
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.Forms
If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:
-Renal Diagnostics Test Request (T830)
-Coagulation Test Request (T753)