Lupus Anticoagulant Comprehensive

CPT: 85613; 85670; 85705; 85732
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Test Details

Test Includes

LA-sensitive activated partial thromboplastin time (aPTT); dilute prothrombin time (dPT); thrombin time. If any of these three screening tests is extended, reflex testing is performed and additional charges/CPT code(s) will apply.

Use

Qualitative detection of lupus anticoagulants in plasma6

Methodology

Lupus-sensitive aPTT and dPT screening tests; mixing study if screening test are prolonged; confirmation if the mixing studies do not correct

Additional Information

Lupus anticoagulants are antibodies that inhibit one or more of the in vitro phospholipid-dependent tests of coagulation.6-10 Recently, the SCC Subcommittee for the Standardization of Lupus Anticoagulants provided guidelines for the laboratory diagnosis of LA.6 No single screening test can detect all LA-positive patients. The ISTH recommends that any sample suspected of having LA be tested using two or more LA screening tests.6,7 The screening tests commonly used to detect LA assess inhibitors of the intrinsic pathway (aPTT) and the common pathways (dRVVT). The dPT assay screens for phospholipid-dependent inhibitors of a different part of the coagulation cascade, the extrinsic pathway.11 The thrombin time is included to rule out heparin and other thrombin inhibitors.

Specimen Requirements

Specimen

Plasma, frozen

Volume

6 mL

Minimum Volume

3 mL

Container

Blue-top (sodium citrate) tube

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.

Collection

Citrated plasma samples should be collected by double centrifugation. Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.1 Evacuated collection tubes must be filled to completion to ensure a proper blood to anticoagulant ratio.2,3 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.4,5 When noncitrate 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 recentrifuge 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.

Storage Instructions

Freeze.

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

Clinical Information

Special Instructions

This test will reflex immediately to aPTT Mixing Studies [117199] if aPTT is five or more seconds above the upper end of the reference interval.

Footnotes

1. 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. 8980376
2. 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. 9620035
3. 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; 2008. NCCLS Document H21-A5:28(5).
4. 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. 9169665
5. 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. 10539100
6. Brandt JT, Triplett DA, Alving B, et al. Criteria for the diagnosis of lupus anticoagulants: An update. On behalf of the Subcommittee on Lupus Anticoagulant/Antiphospholipid Antibody of the Scientific and Standardization Committee of the ISTH. Thromb Haemost. 1995 Dec; 74(4):1185-1190. 8560433
7. Brandt JT, Barna LK, Triplett DA. Laboratory identification of lupus anticoagulants: Results of the Second International Workshop for Identification of Lupus Anticoagulants. On behalf of the Subcommittee on Lupus Anticoagulant/Antiphospholipid Antibodies of the ISTH. Thromb Haemost. 1995 Dec; 74(6):1597-1603. 8772243
8. Alving BM. The antiphospholipid syndrome: Clinical presentation, diagnosis, and patient management. In: Kitchens CS, Alving BM, Kessler CM, eds. Consultative Hemostasis and Thrombosis. Philadelphia, Pa: WB Saunders Co; 2002:181-196.
9. Levine JS, Branch DW, Rauch J. The aAntiphospholipid syndrome. N Engl J Med. 2002 Mar 7; 346(10):752-763. 11882732
10. Greaves M, Cohen H, MacHin SJ, Mackie I. Guidelines on the investigation and management of the antiphospholipid syndrome. Br J Haematol. 2000 Jun; 109(4):704-715. 10929019
11. Arnout J, Vanrusselt M, Huybrechts E, Vermylen J. Optimization of the dilute prothrombin time for the detection of the lupus anticoagulant by use of a recombinant tissue thromboplastin. Br J Haematol. 1994 May; 87(1):94-99. 7947261

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
117054 Lupus Anticoagulant Comp 005201 Dilute Prothrombin Time(dPT) sec 53748-0
117054 Lupus Anticoagulant Comp 005203 dPT Confirm Ratio Ratio 57181-0
117054 Lupus Anticoagulant Comp 109009 Thrombin Time sec 3243-3
117054 Lupus Anticoagulant Comp 117003 PTT-LA sec 34571-0
117054 Lupus Anticoagulant Comp 117891 dRVVT sec 6303-2
117054 Lupus Anticoagulant Comp 117893 Lupus Reflex Interpretation 75514-0
Reflex Table for Thrombin Time
Order Code Order Name Result Code Result Name UofM Result LOINC
Reflex 1 117110 TT Mix+TTN 117171 Thrombin Time Mix sec 33525-7
Reflex Table for Thrombin Time
Order Code Order Name Result Code Result Name UofM Result LOINC
Reflex 1 117110 TT Mix+TTN 117203 Thrombin Neutralization sec 46224-2
Reflex Table for Thrombin Time
Order Code Order Name Result Code Result Name UofM Result LOINC
Reflex 1 117110 TT Mix+TTN 117171 Thrombin Time Mix sec 33525-7
Reflex Table for Thrombin Time
Order Code Order Name Result Code Result Name UofM Result LOINC
Reflex 1 117110 TT Mix+TTN 117203 Thrombin Neutralization sec 46224-2
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 000000 117842 000000 sec 3282-1
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 000000 117036 000000 sec 50760-8 117020
Reflex 3 000000 117842 000000 sec 3282-1

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