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HelpTest Code AH50 Alternative Complement Pathway, Functional, Serum
Reporting Name
Alternative Complement Path Func, SUseful For
Investigation of suspected alternative pathway complement deficiency, atypical hemolytic uremic syndrome, C3 glomerulonephritis, and dense-deposit disease
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumOrdering Guidance
COM / Complement, Total, Serum and this test are the most appropriate primary assays to use as screening methods for complement deficiencies. Abnormal results in one or the other, neither or both assays will help direct further testing.
This test is rarely useful when ordered in isolation.
Specimen Required
Patient Preparation:
Fasting: 8 hours, preferred but not required
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions:
1. Immediately after specimen collection, place the tube on wet ice and allow specimen to clot.
2. Centrifuge at 4° C and aliquot serum into a plastic vial.
3. Freeze specimen within 30 minutes of centrifugation. Specimen must be placed on dry ice if not frozen immediately.
NOTE: If a refrigerated centrifuge is not available, it is acceptable to use a room temperature centrifuge, provided the specimen is kept on ice before centrifugation, and immediately afterward, the serum aliquoted and frozen.
Specimen Minimum Volume
0.75 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Frozen | 14 days |
Reference Values
≥46% normal
Day(s) Performed
Varies
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.CPT Code Information
86161
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| AH50 | Alternative Complement Path Func, S | 74520-8 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 88676 | Alternative Complement Path Func, S | 74520-8 |
Cautions
This assay is a functional test and is dependent on correct sampling, storage, and shipping conditions. Both degradation by temperature and consumption of complement components will lead to false low function results. These are difficult to differentiate from real complement dysregulation.
While preanalytic handling can lead to false-positive results, it is far less likely that it would lead to false-normal results. If more than one component is measured as low, it is important to look for technical errors.
Complement testing may be ordered in several circumstances where standard treatment includes plasmapheresis or plasma exchange. The procedure itself, if traumatic, may activate complement so may not reflect what is going on with the patient's complement system. The recommendation is to collect blood prior to the plasma exchange whenever possible.
Functional results inconsistent with the clinical history should be verified with a new blood draw.
Specimens should be frozen immediately after collection.
Long term stability is optimal when the sample is kept at -70° Celsius or lower prior to testing.
Report Available
3 to 5 daysReject Due To
| Gross hemolysis | OK |
| Gross lipemia | OK |
| Gross icterus | OK |
NY State Approved
YesMethod Name
Enzyme-Linked Immunosorbent Assay (ELISA)
Secondary ID
88676Forms
If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.