Alternative Complement Pathway Activity (AH50)
Also known as: AH50
Use
The Alternative Complement Pathway Activity (AH50) test is used for the initial screening of suspected deficiencies in the alternative complement pathway, which can indicate inherited or acquired deficiencies in complement components or secondary consumption processes. Abnormal activity in this pathway may be associated with various conditions, including atypical hemolytic uremic syndrome, C3 glomerulonephritis, dense-deposit disease, and atypical postinfectious glomerulonephritis.
Special Instructions
The test requires a serum specimen collected in a plain red top tube. It is critical to follow specimen processing instructions to avoid rejection, such as ensuring specimens are separated and frozen promptly. Additionally, grossly hemolyzed or lipemic specimens are not accepted.
Limitations
This test has not been cleared or approved by the U.S. Food and Drug Administration. It is laboratory-developed, and its performance was determined by ARUP Laboratories. Interpretations of low AH50 with normal CH50 can indicate specific pathway defects, while normal AH50 with low CH50 suggests defects in the classical pathway. If results are inconsistent or unexpected, repeat testing with freshly frozen serum is advisable.
New York Approved
Methodology
Immunoassay (ELISA)
Biomarkers
LOINC Codes
- 74520-8
Result Turnaround Time
7-14 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
Not provided
Minimum Volume
0.3 mL
Container
Plain Red
Collection Instructions
Allow specimen to clot for one hour at room temperature. Separate serum from cells ASAP and centrifuge at 2-8 degrees C and aliquot serum into ARUP standard transport tube.
Storage Instructions
Freeze specimen immediately at -70 degrees C or lower.
Causes for Rejection
Specimen types other than serum collected from RED TOP tubes. SST or serum gel tubes are not acceptable. Refrigerated or room temperature specimens. Specimens left to clot at refrigerated temperature. Specimens exposed to repeated freeze/thaw cycles. Grossly hemolyzed or grossly lipemic specimens or icteric specimens.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | unacceptable |
| Refrigerated | Unacceptable |
| Frozen | 30 days if kept at -70 C |