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Test Code LAB1057 Alternative Complement Pathway, Functional, Serum

Additional Codes

Mayo Test ID
AH50

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

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

Method Name

Enzyme-Linked Immunosorbent Assay (ELISA)

Reporting Name

Alternative Complement Path Func, S

Specimen Type

Serum Red


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.


Specimen Minimum Volume

0.2 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Red Frozen 14 days

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

Reference Values

≥46% normal

Interpretation

Absent complement alternative pathway (AH50) in the presence of a normal total hemolytic complement (CH50) suggests an alternative pathway component deficiency.

 

Normal AH50 with absent CH50 suggests an early (C1, C2, C4) classic pathway deficiency.

 

Absent AH50 and CH50 suggests a late (C3, C5, C6, C7, C8, C9) component deficiency or complement consumption.

 

Absent AH50 and CH50 in the presence of a normal C3 and C4 suggests a late (C5, C6, C7, C8, C9) component deficiency.

 

Normal CH50 and AH50 in the presence of recurrent infection and continued suspicion of complement deficiency, suggest testing for lectin pathway function.

Day(s) Performed

Monday, Thursday

Report Available

3 to 5 days

Specimen Retention Time

14 days

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

Forms

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