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Test ID AHUSD Atypical Hemolytic Uremic Syndrome (aHUS) 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-order 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 Complement, Alternate 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 No 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, C5AG2: Nephelometry

COM3: Automated Liposome Lysis Assay

AH503, C4D, CBB, SC5B9: Enzyme-Linked Immunosorbent Assay (ELISA)

Reporting Name

aHUS Complement Panel, S and P

Specimen Type

Plasma Na Cit
Serum Red


Advisory Information


For evaluating patients with possible thrombotic microangiopathies (TMA), the recommended first-order test is ADM13 / ADAMTS13 Activity and Inhibitor Profile. This test, AHUSD, should be a second-order 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 drawn earlier than 48 hours following plasma exchange.

 

Specimen Type: Plasma

Collection Container/Tube: Light-blue top (3.2% sodium citrate)

Submission Container/Tube: Plastic vial

Specimen Volume: 1.5 mL

Collection Instructions:

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

2. Centrifuge; 1,500 x g for 10 minutes at 4° C, and separate plasma from cells.

3. Freeze specimen within 30 minutes.

 

Specimen Type: Serum

Collection Container/Tube: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 1.5 mL

Collection Instructions:

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

2. Centrifuge at 4° C and separate serum from clot.

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

Clinical Information

Individuals presenting with thrombotic microangiopathies (TMAs) 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) 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 TMAs. The suggested approach is to rule-out other causes of TMAs first, since aHUS is one of the rarer causes of TMAs. Additionally, the assays can be used in the setting of membranoproliferative glomerulonephritis (MPGN), and help distinguish between immune-complex mediated or complement-mediated kidney disease. MPGN mediated by immune-complexes are the ones resulting from infectious processes, autoimmune diseases, or monoclonal gammopathies, whereas complement-mediated MPGN can then be subdivided in C3 glomerulonephritis (C3GN) and dense deposit disease (DDD), 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

23.6-43.1 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

 

COMPLEMENT, ALTERNATE PATHWAY (AH50), FUNCTIONAL

≥46% normal

 

COMPLEMENT, TOTAL

≥16 years: 30-75 U/mL

Reference values have not been established for patients who are <16 years of age.

Interpretation

An interpretive report will be included.

Clinical Reference

1. Daha MR: Role of complement in innate immunity and infections. Crit Rev Immunol 2010;30(1):47-52

2. Prohaszka Z, Varga L, Fust G: The use of "real-time" complement analysis to differentiate atypical haemolytic uraemic syndrome from other forms of thrombotic microangiopathies. Br J Haematol 2012;158(3):424-425

3. Cataland SR, Holers VM, Geyer S, et al: Biomarkers of terminal complement activation confirm the diagnosis of aHUS and differentiate aHUS from TTP. Blood 2014;123(24):3733-3738

Day(s) and Time(s) Performed

Varies

Analytic Time

12 days

CPT Code Information

86160 x 7

86161

86162

LOINC Code Information

Test ID Test Order Name Order LOINC Value
AHUSD aHUS Complement Panel, S and P In Process

 

Result ID Test Result Name Result LOINC Value
62584 C4d Complement, P 39565-7
62585 CBb Complement, P 4517-9
FBCA Factor B Complement Antigen, S 2269-9
FHCA Factor H Complement Antigen, S 4519-5
62586 SC5b-9 Complement, P 93244-2
38316 Complement, Alternate Path, Func, S 74520-8
COM3 Complement, Total, S 4532-8
C3HUS Complement C3, S 4485-9
C4HUS Complement C4, S 4498-2
39844 AHUS Interpretation 69048-7
ECPRO Is patient receiving Eculizumab? 86955-2

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. 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)