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Lupus Anticoagulant With Reflex

Test Number 117892
Test number copied
CPT

85613; 85732. If reflex testing is performed, concomitant CPT codes/charges will apply.
Synonyms
  • Lupus Anticoagulant
  • Lupus Anticoagulant Screen

Test Details

Methodology

PTT-LA (lupus-sensitive aPTT) and dRVVT screen; mixing study if screening tests are prolonged; confirmation if the mixing studies do not correct

Result Turnaround Time

2 - 3 days

Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Related Information

Related Documents

For more information, please view the literature below.

Use

This test is used for qualitative detection of lupus anticoagulants in plasma.

Limitations

Patients with high clinical suspicion of having APS, but without presence of criteria aPL, are suggested to have “seronegative APS” (SNAPS). These patients may be positive for so-called non-criteria aPL or be negative for the criteria aPL through insufficient sensitivity of the assays.11,24 

Inherent to the test principle of phospholipid-based coagulation assays, LAC testing is prone to interferences. 

  • Elevated c-reactive protein interferes in vitro with aPTT testing through its affinity for phospholipids, leading to false-positive results of the LAC test.25

  • Increased factor VIII (FVIII) coagulant activity is associated with shorter aPTT clotting times and can lead to false-negative LAC aPTT screening assays.26 dRVVT screening is not influenced by FVIII levels as factor X is directly activated by Russell’s viper venom. Increased levels of FVIII can be observed during pregnancy, surgery, inflammation, malignancy and other conditions.27 

  • LAC is often found to be positive during inflammatory conditions, without clear association with a clinical APS phenotype, recently highlighted in patients with coronavirus disease 2019.28 LA positivity after viral and bacterial infections is often transient and not accompanied by the clinical APS phenotype.29 

  • Certain drugs (e.g., antibiotics, antiarrhythmics and chlorpromazine) and to a lesser extent vaccines (e.g., against hepatitis B virus) are also found to be associated with LA activity.29 

  • In the acute setting of thrombosis, increased FVIII levels can lead to false-negative LA assessment, while increased CRP can lead to false-positive LA testing. Therefore, it is not recommended to assess LAC status during the thrombotic event or in patients with acute inflammation. Retesting patients with LAC positivity, at least 12 weeks after the initial finding, is an important strategy in avoiding misclassification of patients with transient LAC.4 

  • Anticoagulation treatment complicates LAC testing and interpretation by prolonging aPTT and dRVVT. LAC testing during anticoagulation treatment is discouraged,4 although it is not always desirable to postpone LAC analysis until treatment cessation.20 

  • Vitamin K antagonists (i.e., warfarin) can cause prolongation of aPTT and dRVVT through production of incomplete coagulation factors by inhibition of vitamin K-dependent gamma carboxylation of factors II (prothrombin), VII, IX and X.30 This acquired factor deficiency can lead to false-positive interpretation of LA testing, especially in the screening step, and false negative in the mixing step. 

  • Unfractionated heparin (UFH), LMWH and heparinoids mainly interfere by indirectly inhibiting thrombin and activated factor X (FXa) action.31 dRVVT and the PTT-LA reagents contain heparin-neutralizing agents, quenching the effect of heparin in vitro. 

  • Direct Oral Anticoagulants (DOACs) directly inhibit thrombin (e.g., dabigatran) or Factor Xa (e.g., apixaban, betrixaban, edoxaban and rivaroxaban),32 with various effects on coagulation tests, even at trough levels, leading to both false-negative and false-positive LA interpretation.33-36 Adsorption of DOACs from plasma prior to testing can overcome DOAC interference in vitro. 

Custom Additional Information

Antiphospholipid syndrome (APS) represents a serious clinical condition in which patients may be at high risk for thrombosis, pregnancy/fetal morbidity/mortality, or other multi-system clinical presentations.1 The latest APS classification criteria2 identify patients as having definite APS based on a clinical and laboratory scoring system as the entry criterion and persistent presence of certain antiphospholipid antibodies (aPL). These aPL tests are also more broadly used to diagnose or exclude APS.3 

Antiphospholipid syndrome (APS) is an acquired autoimmune disorder that manifests clinically as recurrent venous, arterial and/or small vessel thrombosis and/or fetal loss in the context of persistently positive antiphospholipid antibodies (aPL).4-9 At least one clinical criterion and one laboratory criterion must be present for a patient to be classified as having APS. The clinical criteria consist of vascular thrombosis and pregnancy morbidity. 

Vascular thrombosis is defined as the following: 

  • One or more clinical episodes of arterial, venous, or small-vessel thrombosis in any tissue or organ confirmed by findings from imaging studies, Doppler studies or histopathology. 

  • Thrombosis may involve the cerebral vascular system, coronary arteries, pulmonary system (emboli or thromboses), arterial or venous system in the extremities, hepatic veins, renal veins, ocular arteries or veins or adrenal glands. 

Investigation is warranted if a history of deep venous thrombosis, pulmonary embolism, acute ischemia, myocardial infarction (MI) or stroke (especially when recurrent) is present in a younger individual (males <55 y; females <65 y) or in the absence of other risk factors. 

Pregnancy morbidity is defined as the following: 

  • One or more late-term (>10 weeks' gestation) spontaneous abortions. 

  • One or more premature births of a morphologically healthy neonate at or before 34 weeks’ gestation because of severe preeclampsia or eclampsia or severe placental insufficiency.

  • Three or more unexplained, consecutive, spontaneous abortions before 10 weeks’ gestation.

Besides the criteria currently regarded as classification criteria for APS, other manifestations such as thrombocytopenia, autoimmune hemolytic anemia, livedo reticularis, neurologic manifestations, nephropathy and valvular heart disease are associated with presence of aPL.10-13 

In addition to the clinical criteria, at least one of the following laboratory criteria is necessary for the classification of APS:4-8 

  • Presence of lupus anticoagulant (LA) in plasma on two or more occasions at least 12 weeks apart. 

  • Presence of moderate to high levels of anticardiolipin (aCL; IgG or IgM) in serum on two or more occasions at least 12 weeks apart.5

  • Presence of moderate to high levels of anti–beta-2 glycoprotein I antibodies (β2GP1; IgG or IgM) in serum on two or more occasions at least 12 weeks apart.5 

Lupus Anticoagulant Testing 

Current LA testing guidelines recommend use of at least two tests based on different assay principles before excluding LA, recommending the activated partial thromboplastin time (aPTT) and dilute Russell viper venom time (dRVVT).4,6,14 The aPTT is based on contact activation, and the dRVVT is based on factor (F)X activation.15,16 

Lupus anticoagulants (LA) are nonspecific autoantibodies that extend the clotting time of phospholipid-dependent clotting assays.4-8 LA do not specifically inhibit individual coagulation factors; rather they neutralize anionic phospholipid-protein complexes that are involved in the coagulation process. The International Society of Thrombosis and Haemostasis (ISTH) has established criteria for the identification of LA by clot-based assays.4 Prolongation of clot-based assays is dependent on the sensitivity of the reagent employed to detect the presence of LA. Assays are made more sensitive for LA by decreasing the amount of phospholipid in the reagent. The ISTH guidelines call for the use of two LA-sensitive reagent systems in testing for LA as no single test has sufficient sensitivity and specificity.4-8 Both assays are complementary as aPL do not always react in both test systems.17 The most recent update of the ISTH guidelines on LA detection recommends parallel testing of the dilute Russell’s viper venom time (dRVVT) and aPTT.4

The dilute Russell Viper Venom Time (dRVVT) dilute and activated Partial Thromboplastin Time (aPTT-LA) are the most used tests for LA and are specifically mentioned in the guidelines.4 The dRVVT assay is based on direct activation of factor X by an enzyme present in the venom of Russell’s vipers. aPL in patient plasma will react with phospholipid components of the reagent through cofactors and prolong the dRVVT by decreased activity of the prothrombin activator complex.18 The aPTT-LA assay is based on activation of the contact (intrinsic) pathway. Analogous to the dRVVT assay, aPL inhibit phospholipid-dependent steps in the aPTT coagulation pathway. A prolonged clotting time in either screening test is followed by demonstration of phospholipid dependence and inhibitory properties in confirmatory and mixing tests, respectively, which are modifications of the parent screening test. In order for an extended screening result to be interpreted as a lupus anticoagulant, the assay clotting time must exhibit correction (reduced clotting time) on re-addition of phospholipid in what is referred to as a “confirmation” assay. 

The Labcorp LA reflex testing procedure was designed based on the recommendations of the Scientific and Standardization Committee for lupus anticoagulant/antiphospholipid antibodies of the ISTH updated in 2020.4 The three-step procedure starts with performance of the two LA-sensitive screening tests (PTT-LA and dRVVT). Samples with prolonged screening results for either of these tests are further tested by a mixing test (to exclude a deficiency in coagulation factor as the cause of the extended screening test) and a confirmation test (to ascertain if a phospholipid dependent inhibitor (LA) is detected). The LAC testing is considered positive if one of the two test systems gives a positive confirmation result.4 

Specimen Requirements

Specimen

Plasma, frozen

Volume

2 mL

Minimum Volume

1 mL (Note: This volume does not allow for repeat testing.)

Container

Blue-top (sodium citrate) tube

Collection Instructions

Citrated plasma samples should be collected by double centrifugation. Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.19 Evacuated collection tubes must be filled to completion to ensure a proper blood to anticoagulant ratio.20,21 The sample should be mixed immediately by gentle inversion at least six times to ensure adequate mixing of the anticoagulant with the blood. A discard tube is not required prior to collection of coagulation samples unless the sample is collected using a winged (butterfly) collection system. With a winged blood collection set a discard tube should be drawn first to account for the dead space of the tubing and prevent under-filling of the evacuated tube.22,23 When non-citrate tubes are collected for other tests, collect sterile and nonadditive (red-top) tubes prior to citrate (blue-top) tubes. Any tube containing an alternate anticoagulant should be collected after the blue-top tube. Gel-barrier tubes and serum tubes with clot initiators should also be collected after the citrate tubes. Centrifuge for 10 minutes and carefully remove 2/3 of the plasma using a plastic transfer pipette, being careful not to disturb the cells. Deliver to a plastic transport tube, cap, and re-centrifuge for 10 minutes. Use a second plastic pipette to remove the plasma, staying clear of the platelets at the bottom of the tube. Transfer the plasma into a Labcorp PP transpak frozen purple tube with screw cap (Labcorp No. 49482). Freeze immediately and maintain frozen until tested.

Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.

Stability Requirements

TemperaturePeriod
Frozen28 days
Freeze/thaw cyclesStable x3

Storage Instructions

Freeze.

Patient Preparation

Ideally, the patient should not be on anticoagulant therapy. Avoid warfarin (Coumadin®) therapy for two weeks prior to the test and heparin, direct Xa, and thrombin inhibitor therapies for about three days prior to testing.

Causes for Rejection

Severe hemolysis; improper labeling; clotted specimen; specimen diluted with IV fluids; samples thawed in transit; improper sample type; sample out of stability

Footnotes

  1. Knight JS, Branch DW, Ortel TL. Antiphospholipid syndrome: advances in diagnosis, pathogenesis, and management. BMJ. 2023 Feb 27;380:e069717. PubMed 36849186

  2. Barbhaiya M, Zuily S, Naden R, et al. 2023 ACR/EULAR antiphospholipid syndrome classification criteria. Arthritis Rheumatol. 2023 Oct;75(10):1687-1702. PubMed 37635643

  3. Vandevelde A, Devreese KMJ. Laboratory diagnosis of antiphospholipid syndrome: insights and hindrances. J Clin Med. 2022 Apr 13;11(8):2164. PubMed 35456258

  4. Devreese KMJ, de Groot PG, de Laat B, et al. Guidance from the Scientific and Standardization Committee for lupus anticoagulant /antiphospholipid antibodies of the International Society on Thrombosis and Haemostasis: Update of the guidelines for lupus anticoagulant detection and interpretation. J Thromb Haemost. 2020 Nov;18(11):2828-2839. PubMed 33462974

  5. Devreese KM, Ortel TL, Pengo V, de Laat B. Laboratory criteria for antiphospholipid syndrome: reply. J Thromb Haemost. 2018;16(10):2117-2119. PubMed 30007111

  6. Keeling D, Mackie I, Moore GW, Greer IA, Greaves M, British Committee for Standards in Haematology. Guidelines on the investigation and management of antiphospholipid syndrome. Br J Haematol. 2012 Apr;157(1):47-58. PubMed 22313321

  7. Pengo V, Tripodi A, Reber G, et al. Update of the guidelines for lupus anticoagulant detection. Subcommittee on Lupus Anticoagulant/Antiphospholipid Antibody of the Scientific and Standardisation Committee of the International Society on Thrombosis and Haemostasis. J Thromb Haemost. 2009 Oct;7(10):1737-1740. PubMed 19624461

  8. Miyakis S, Lockshin MD, Atsumi T, et al. International consensus statement on an update of the classification criteria for definite antiphospholipid syndrome (APS). J Thromb Haemost. 2006 Feb;4(2):295-306. PubMed 16420554

  9. Favaloro EJ, Pasalic L, Selby R. Testing for the lupus anticoagulant: the good, the bad, and the ugly. Res Pract Thromb Haemost. 2024 Mar 18;8(3):102385. PubMed 38623474

  10. Abreu MM, Danowski A, Wahl DG, et al. The relevance of "non-criteria" clinical manifestations of antiphospholipid syndrome: 14th International Congress on Antiphospholipid Antibodies Technical Task Force Report on Antiphospholipid Syndrome Clinical Features. Autoimmun Rev. 2015;14(5):401-414. PubMed 25641203

  11. Bernardoff I, Picq A, Loiseau P, et al. Antiphospholipid antibodies and the risk of autoimmune hemolytic anemia in patients with systemic lupus erythematosus: A systematic review and meta-analysis. Autoimmun Rev. 2022 Jan;21(1):102913. PubMed 34371159

  12. Chock YP, Moulinet T, Dufrost V, Erkan D, Wahl D, Zuily S. Antiphospholipid antibodies and the risk of thrombocytopenia in patients with systemic lupus erythematosus: A systematic review and meta-analysis. Autoimmun Rev. 2019 Nov;18(11):102395. PubMed 31520800

  13. Zuily S, Regnault V, Selton-Suty C, et al. Increased risk for heart valve disease associated with antiphospholipid antibodies in patients with systemic lupus erythematosus: meta-analysis of echocardiographic studies. Circulation. 2011 Jul 12;124(2):215-224. PubMed 21690492

  14. Clinical and Laboratory Standards Institute (CLSI). Laboratory testing for the lupus anticoagulant; approved guideline. CLSI document H60-A. Wayne, PA: CLSI; 2014.

  15. Tripodi A, Chantarangkul V. Lupus anticoagulant testing: activated partial thromboplastin time (APTT) and silica clotting time (SCT). Methods Mol Biol. 2017;1646:177-183. PubMed 28804829

  16. Pengo V, Bison E, Banzato A, Zoppellaro G, Jose SP, Denas G. Lupus anticoagulant testing: diluted Russell Viper venom time (dRVVT). Methods Mol Biol. 2017;1646:169-176. PubMed 28804828

  17. Simmons DP, Herskovits AZ, Battinelli EM, Schur PH, Lemire SJ, Dorfman DM. Lupus anticoagulant testing using two parallel methods detects additional cases and predicts persistent positivity. Clin Chem Lab Med. 2018 Jul 26;56(8):1289-1296. PubMed 27305702

  18. Thiagarajan P, Pengo V, Shapiro SS. The use of the dilute Russell viper venom time for the diagnosis of lupus anticoagulants. Blood. 1986 Oct;68(4):869-874. PubMed 3092888

  19. Adcock DM, Kressin DC, Marlar RA. Effect of 3.2% vs 3.8% sodium citrate concentration on routine coagulation testing. Am J Clin Pathol. 1997 Jan;107(1):105-110. PubMed 8980376

  20. Reneke J, Etzell J, Leslie S, Ng VL, Gottfried EL. Prolonged prothrombin time and activated partial thromboplastin time due to underfilled specimen tubes with 109 mmol/L (3.2%) citrate anticoagulant. Am J Clin Pathol. 1998 Jun;109(6):754-757. PubMed 9620035

  21. National Committee for Clinical Laboratory Standardization. Collection, Transport, and Processing of Blood Specimens for Coagulation Testing and General Performance of Coagulation Assays; Approved Guideline. 5th ed. Villanova, Pa: NCCLS; 2008. Document H21-A5:28(5).

  22. Gottfried EL, Adachi MM. Prothrombin time and activated partial thromboplastin time can be performed on the first tube. Am J Clin Pathol. 1997 Jun;107(6):681-683. PubMed 9169665

  23. McGlasson DL, More L, Best HA, Norris WL, Doe RH, Ray H. Drawing specimens for coagulation testing: Is a second tube necessary? Clin Lab Sci. 1999 May-Jun;12(3):137-139. PubMed 10539100

  24. Conti F, Andreoli L, Crisafulli F, Mancuso S, Truglia S, Tektonidou MG. Does seronegative obstetric APS exist? "pro" and "cons." Autoimmun Rev. 2019 Dec;18(12):102407. PubMed 31639518

  25. Devreese KM, Verfaillie CJ, De Bisschop F, Delanghe JR. Interference of C-reactive protein with clotting times. Clin Chem Lab Med. 2015 Apr;53(5):e141-145. PubMed 25324454

  26. Ten Boekel E, Bartels P. Abnormally short activated partial thromboplastin times are related to elevated plasma levels of TAT, F1+2, D-dimer and FVIII:C. Pathophysiol Haemost Thromb. 2002 May-Jun;32(3):137-142. PubMed 12372929

  27. Kamphuisen PW, Eikenboom JC, Bertina RM. Elevated factor VIII levels and the risk of thrombosis. Arterioscler Thromb Vasc Biol. 2001 May;21(5):731-738. PubMed 11348867

  28. Foret T, Dufrost V, Salomon Du Mont L, et al. Systematic Review of Antiphospholipid Antibodies in COVID-19 Patients: Culprits or Bystanders? Curr Rheumatol Rep. 2021 Jul 3;23(8):65. PubMed 34218350

  29. Martirosyan A, Aminov R, Manukyan G. Environmental Triggers of Autoreactive Responses: Induction of Antiphospholipid Antibody Formation. Front Immunol. 2019 Jul 10;10:1609. PubMed 31354742

  30. Wallin R, Hutson SM. Warfarin and the vitamin K-dependent gamma-carboxylation system. Trends Mol Med. 2004 Jul;10(7):299-302. PubMed 15242675

  31. Hemker HC. A century of heparin: past, present and future. J Thromb Haemost. 2016 Dec;14(12):2329-2338. PubMed 27862941

  32. Chan N, Sobieraj-Teague M, Eikelboom JW. Direct oral anticoagulants: evidence and unresolved issues. Lancet. 2020 Nov 28;396(10264):1767-1776. PubMed 33248499

  33. Antovic A, Norberg EM, Berndtsson M, et al. Effects of direct oral anticoagulants on lupus anticoagulant assays in a real-life setting. Thromb Haemost. 2017 Aug 30;117(9):1700-1704. PubMed 28640321

  34. Gay J, Duchemin J, Imarazene M, Fontenay M, Jourdi G. Lupus anticoagulant diagnosis in patients receiving direct oral FXa inhibitors at trough levels: A real-life study. Int J Lab Hematol. 2019 Dec;41(6):738-744. PubMed 31487115

  35. Martinuzzo ME, Forastiero R, Duboscq C, et al. False-positive lupus anticoagulant results by DRVVT in the presence of rivaroxaban even at low plasma concentrations. Int J Lab Hematol. 2018 Oct;40(5):e99-e101. PubMed 29809321

  36. Favaloro EJ, Mohammed S, Curnow J, Pasalic L. Laboratory testing for lupus anticoagulant (LA) in patients taking direct oral anticoagulants (DOACs): potential for false positives and false negatives. Pathology. 2019 Apr;51(3):292-300. PubMed 30665674

 

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
117892 Lupus Anticoagulant Reflex 75515-7 117003 PTT-LA sec 34571-0
117892 Lupus Anticoagulant Reflex 75515-7 117891 dRVVT sec 6303-2
117892 Lupus Anticoagulant Reflex 75515-7 117893 Lupus Reflex Interpretation 75514-0
Order Code117892
Order Code NameLupus Anticoagulant Reflex
Order Loinc75515-7
Result Code117003
Result Code NamePTT-LA
UofMsec
Result LOINC34571-0
Order Code117892
Order Code NameLupus Anticoagulant Reflex
Order Loinc75515-7
Result Code117891
Result Code NamedRVVT
UofMsec
Result LOINC6303-2
Order Code117892
Order Code NameLupus Anticoagulant Reflex
Order Loinc75515-7
Result Code117893
Result Code NameLupus Reflex Interpretation
UofM
Result LOINC75514-0
Reflex Table for PTT-LA
Order Code Order Name Result Code Result Name UofM Result LOINC
Reflex 1 117040 PTT-LA Mix 117005 PTT-LA Mix sec 75510-8
Reflex 2 117020 Hexagonal Phase Phospholipid 117842 Hexagonal Phase Phospholipid sec 3282-1
Reflex 1
Order Code117040
Order NamePTT-LA Mix
Result Code117005
Result NamePTT-LA Mix
UofMsec
Result LOINC75510-8
Reflex 2
Order Code117020
Order NameHexagonal Phase Phospholipid
Result Code117842
Result NameHexagonal Phase Phospholipid
UofMsec
Result LOINC3282-1
Reflex Table for dRVVT
Order Code Order Name Result Code Result Name UofM Result LOINC
Reflex 1 117912 dRVVT Mix 117894 dRVVT Mix sec 75513-2
Reflex 2 117923 dRVVT Confirm 117924 dRVVT Confirm ratio 50410-0
Reflex 1
Order Code117912
Order NamedRVVT Mix
Result Code117894
Result NamedRVVT Mix
UofMsec
Result LOINC75513-2
Reflex 2
Order Code117923
Order NamedRVVT Confirm
Result Code117924
Result NamedRVVT Confirm
UofMratio
Result LOINC50410-0