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Test Code PSPTG Phosphatidylserine/Prothrombin Antibody, IgG, Serum

Useful For

Detecting IgG antibodies against phosphatidylserine/prothrombin complex in patients with strong suspicion of antiphospholipid syndrome (APS) who are negative for the APS criteria laboratory tests (lupus anticoagulant, IgG and IgM anticardiolipin/beta 2-glycoprotein I and anti-beta 2-glycoprotein I antibodies)

 

May be useful for the evaluation of patients with prior positive lupus anticoagulant results who are on direct oral anticoagulant therapy

 

May be useful as a risk marker for thrombosis in antiphospholipid antibody carriers

Reporting Name

PS/PT Ab, IgG, S

Specimen Type

Serum


Ordering Guidance


Cardiolipin and beta-2 glycoprotein testing are the first-tier test options for most patients. Phosphatidylserine/prothrombin antibodies are considered part of the second-tier workup.



Specimen Required


Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Collection Instructions: Centrifuge and aliquot serum into a plastic vial.


Specimen Minimum Volume

0.4 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 21 days
  Frozen  21 days

Reference Values

Negative ≤30.0 U

Borderline 30.1-40.0 U

Positive ≥40.1 U

Interpretation

A positive and persistent result for anti-phosphatidylserine/prothrombin complex IgG antibodies may be suggestive of a diagnosis of antiphospholipid syndrome (APS) in patients with evidence of arterial, venous, or specific pregnancy-related morbidities. These antibodies may also exist prior to the occurrence APS clinical manifestations as well as in patients with other systemic autoimmune diseases such systemic lupus erythematosus.

 

Anti-phosphatidylserine/prothrombin complex IgG antibodies have relatively higher correlations with positive results for lupus anticoagulant than the IgM isotype as well as significant risk for APS-associated thrombotic events compared to the IgM isotype in antiphospholipid antibody carriers.

 

A negative result does not exclude a diagnosis of APS, as other phospholipid and/or protein antibodies are also associated with this disorder.

Clinical Reference

1. Barbhaiya M, Zuily S, Naden R, et al. The 2023 ACR/EULAR antiphospholipid syndrome classification criteria. Arthritis Rheumatol. 2023;75(10):1687-1702. doi:10.1002/art.42624

2. Pengo V, Bison E, Denas G, Jose SP, Zoppellaro G, Banzato A. Laboratory diagnostics of antiphospholipid syndrome. Semin Thromb Hemost. 2018;44(5):439-444. doi:10.1055/s-0037-1601331

3. Tebo AE. Laboratory evaluation of antiphospholipid syndrome: An update on autoantibody testing. Clin Lab Med. 2019;39(4):553-565. doi:10.1016/j.cll.2019.07.004

4. Sciascia S, Sanna G, Murru V, Roccatello D, Khamashta MA, Bertolaccini ML. Anti-prothrombin (aPT) and anti-phosphatidylserine/prothrombin (aPS/PT) antibodies and the risk of thrombosis in the antiphospholipid syndrome. A systematic review. Thromb Haemost. 2014;111(2):354-364. doi:10.1160/TH13-06-0509

5. Amengual O, Forastiero R, Sugiura-Ogasawara M, et al. Evaluation of phosphatidylserine-dependent antiprothrombin antibody testing for the diagnosis of antiphospholipid syndrome: results of an international multicentre study. Lupus. 2017;26(3):266-276. doi:10.1177/0961203316660203

6. Heikal NM, Jaskowski TD, Malmberg E, Lakos G, Branch DW, Tebo AE. Laboratory evaluation of anti-phospholipid syndrome: A preliminary prospective study of phosphatidylserine/prothrombin antibodies in an at-risk patient cohort. Clin Exp Immunol. 2015;180(2):218-226. doi:10.1111/cei.12573

7. Nakamura H, Oku K, Amengual O, et al. First-line, non-criterial antiphospholipid antibody testing for the diagnosis of antiphospholipid syndrome in clinical practice: A combination of anti-beta 2 -glycoprotein I domain I and anti-phosphatidylserine/prothrombin complex antibodies tests. Arthritis Care Res (Hoboken). 2018;70(4):627-634

8. Radin M, Foddai SG, Cecchi I, et al. Antiphosphatidylserine/prothrombin antibodies: An update on their association with clinical manifestations of antiphospholipid syndrome. Thromb Haemost. 2020;120(4):592-598. doi:10.1055/s-0040-1705115

9. Nunez-Alvarez CA, Hernandez-Molina G, Bermudez-Bermejo P, et al. Prevalence and associations of anti-phosphatidylserine/prothrombin antibodies with clinical phenotypes in patients with primary antiphospholipid syndrome: aPS/PT antibodies in primary antiphospholipid syndrome. Thromb Res. 2019;174:141-147. doi:10.1016/j.thromres.2018.12.023

10. Tonello M, Mattia E, Favaro M, et al. IgG phosphatidylserine/prothrombin antibodies as a risk factor of thrombosis in antiphospholipid antibody carriers. Thromb Res. 2019;177:157-160. doi:10.1016/j.thromres.2019.03.006

Day(s) Performed

Wednesday

Report Available

2 to 8 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

86148

LOINC Code Information

Test ID Test Order Name Order LOINC Value
PSPTG PS/PT Ab, IgG, S 85359-8

 

Result ID Test Result Name Result LOINC Value
PSPTG PS/PT Ab, IgG, S 85359-8

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.