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Test Code LABTHSD7 Thrombospondin Type-1 Domain-Containing 7A Antibodies, Serum

Additional Codes

Test Name in EPIC EPIC Test Code Mnemonic Mayo Test ID

THROMBOSPONDIN TYPE-1 DOMAIN-CONTAINING 7A ANTIBODIES

 LABTHSD7 THSD7 THSD7

 


Specimen Required


Supplies: Sarstedt 5 mL Aliquot Tube (T914)

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container: Plastic vial

Specimen Volume: 1 mL

Collection Information: Centrifuge and aliquot serum into plastic vial within 2 hours of collection.


Useful For

Distinguishing primary from secondary membranous nephropathy cases with antibodies against THSD7A

Method Name

Indirect Immunofluorescence Assay (IFA)

Reporting Name

THSD7A Ab, S

Specimen Type

Serum

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 14 days
  Frozen  14 days
  Ambient  8 hours

Reject Due To

Gross hemolysis Reject
Gross lipemia OK

Clinical Information

Recently, autoantibodies against phospholipase A2 receptor (PLA2R) in the kidney were determined to be the major target antigen for patients with idiopathic/primary membranous nephropathy (MN).(1) Approximately 70% of patients with primary MN circulate anti-PLA2R antibodies, and in the remaining 30% (who are PLA2R-negative), anti-thrombospondin type-1 domain-containing 7A (THSD7A) was shown to have approximately a 10% prevalence (or about 3% of all primary MN patients).(2) Mouse podocytes express THSD7A and introduction of anti-THSD7A autoantibodies induces MN in murine models. Mouse podocytes do not express PLA2R so exogenous administration of anti-PLA2R does not recapitulate membranous nephropathy in mice.(3) Additionally, THSD7A has been described as a potential tumor antigen and, thus, it has been suggested that THSD7A-positive patients merit a thorough cancer screening.(4)

Reference Values

Negative

Interpretation

Therapy outcome can be monitored by measuring the antibody titer. A titer increase, decrease, or disappearance generally precedes a change in clinical status. Thus, the determination of the antibody titer has a high predictive value with respect to clinical remission, relapse, or risk assessment after kidney transplantation.

Cautions

This test should not be used as a stand-alone test but as an adjunct to other clinical information. A diagnosis of primary or secondary membranous nephropathy (MN) should not be made based on a single test result. The clinical symptoms, results on physical examination, and laboratory tests (eg, serological tests), when appropriate, should always be taken into account when considering the diagnosis of primary versus secondary MN.

 

Absence of circulating autoantibodies does not rule out a diagnosis of primary MN.

Method Description

Diluted patient samples are incubated with combinations of substrates. If the reaction is positive, specific antibodies of classes IgA, IgG, and IgM attach to the antigens. In a second step, the attached antibodies are stained with fluorescein-labelled antihuman antibodies and made visible with a fluorescence microscope.(Package insert: Anti-THSD7A IIFT EUROPattern, EUROIMMUN US;V 06/11/2019)

Day(s) Performed

Tuesday

Report Available

3 to 7 days

Specimen Retention Time

7 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

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

86255

LOINC Code Information

Test ID Test Order Name Order LOINC Value
THSD7 THSD7A Ab, S 93339-0

 

Result ID Test Result Name Result LOINC Value
THSD7 THSD7A Ab, S 93339-0

Forms

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