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Test Code LAB2782 Alternative Complement Pathway, Functional, Serum

Important Note

Immediately after drawing the specimen, place the tube on wet ice.

Additional Codes

AH50

Reporting Name

Alternative Complement Path Func, S

Useful For

Investigation of suspected alternative pathway complement deficiency, atypical hemolytic uremic syndrome, C3 glomerulonephritis, and dense-deposit disease


Ordering 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: Patient should be fasting.

Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container/Tube: Red top (serum gel/SST are not acceptable)

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

1. Immediately after specimen collection, place the tube on wet ice.

2. After sample has clotted on wet ice, centrifuge at 4° C and aliquot serum into a plastic vial.

3. Freeze specimen within 30 minutes of centrifugation. Sample 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.


Seattle Children's Hospital Note:

Collect 2.0 mL whole blood in a Red top.

Specimen Type

Serum Red

Specimen Minimum Volume

0.2 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Red Frozen 14 days

Day(s) Performed

Monday, Thursday

Seattle Children's Hospital Note:

TAT: 3 - 9 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Method Name

Enzyme-Linked Immunosorbent Assay (ELISA)

Method Description

The Wieslab enzyme-linked immunosorbent assay complement assay for the alternative pathway combines principles of the hemolytic assay for complement activation with the use of labeled antibodies specific for neoantigens produced as a result of complement activation. The micro titer plate strips are coated with lipopolysaccharide. Patient serum is diluted in diluent containing specific blocker to ensure that only the alternative pathway is activated. During the first incubation, the diluted patient serum in the wells is activated by the coating. The wells are then washed and C5b-9 (membrane attack complex: MAC) is detected with a specific alkaline phosphatase labeled antibody to the neoantigen expressed during MAC formation. After a final wash, an alkaline phosphatase substrate is added. The amount of alternative pathway complement activity correlates with the color intensity of the solution and is measured in terms of absorbance (optical density).(Frazer-Abel A, Sepiashvili L, Mbughuni MM, Willrich MA. Overview of laboratory testing and clinical presentations of complement deficiencies and dysregulation. Adv Clin Chem. 2016;77:1-75. doi:10.1016/bs.acc.2016.06.001)

Reference Values

≥46% normal

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

Report Available

3 to 5 days

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

Forms

If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.