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Lupus Anticoagulant by HEXA

Item Value
Clinical Questions Does my patient have antiphospholipid syndrome (APLS)?
Approval req'd? No
Available Stat? No
Utilization Guidelines When lupus anticoagulant testing is requested, it is appropriate to perform BOTH the RVVT and Lupus Anticoagulant by HEXA tests. For this reason, both will be performed whenever either is ordered. In the uncommon circumstance that a provider wishes to perform only one of these tests, the hematology laboratory should be contacted at 353-1747 to request that only the single test be performed.
Test code HEXA
Test group Anti-phospholipid
Performed by Parnassus Hematology
In House Availability Tuesday, day shift
Method Hexagonal Phospholipid Neutralization Test
Collection Instructions When lupus anticoagulant testing is requested, it is appropriate to perform BOTH the RVVT and Lupus Anticoagulant by HEXA tests. For this reason, both will be performed whenever either is ordered. In the uncommon circumstance that a provider wishes to perform only one of these tests, the hematology laboratory should be contacted at 353-1747 to request that only the single test be performed.

1. Check the expiration date on the label of the blue top vacutainer before drawing the patient.

2. For blood collection in a sodium citrate blue top, the tube must be filled to above the Minimum Fill Indicator on the tube. It is crucial to wait and allow the tube to stop filling before removing it from the needle.

3. With use of a butterfly needle, draw about 1 cc using a separate blue top to remove air from tubing, discard the first tube and then draw a second blue top tube filled to the full extent of the vacuum.

4. Tubes should not be filled past the Maximum Fill dashed line by either using a syringe or removing the tube cap.

Bring specimen immediately to lab after collection.

For patients with Hct's ≥ 55% please contact Hematology (x3-1747) to obtain blue top tubes with adjusted citrate volumes in order to maintain the proper citrate to plasma ratio for coagulation studies.

NOTE: Thrombin inhibitors (e.g. hirudin, argatroban) present in the sample to be tested may interfere in the test and lead to falsely positive results, for patients receiving such therapy please contact the Hematology lab (x3-1747) BEFORE collecting samples for testing.
Container type Blue top filled to full extent of vacuum
Amount to Collect 2.7 mL blood
Sample type Citrated plasma
Preferred volume 1 mL plasma
UCSF Rejection Criteria Hemolysis, sample collected in glass tube. Samples collected in outdated blue top vacutainer. Over-filled or under-filled tubes may be rejected
Processing notes Platelet poor plasma required and must be frozen within 4 hours of collection.

Note: If Lupius Anticoagulant ordered without further specification order both HEXA and RVVTM
Normal range Negative
Synonyms LA; antiphospholipid AB; Anti-cardiolipin; HEXA; RVVT; Russel's viper venom; Hexagonal phospholipid neutralization
Additional information Summary of Interpretive Information for test results:

A negative test result in this assay does not exclude the possibility of a lupus anticoagulant. Current guidelines suggest testing for lupus anticoagulant with two clot based tests (J Thromb Haemost 2009; 7: 1737-40): in addition to this lupus anticoagulant by HEXA, the RVVT-based assay is recommended for detecting lupus anticoagulants. Lupus anticoagulant testing should be considered positive if one of the two tests gives a positive result.

Testing for lupus anticoagulant in the presence of anticoagulant therapy (including warfarin, direct thrombin inhibitors & direct factor 10a inhibitors, and supratherapeutic heparin) is not recommended due to possible interference with test results. The presence of factor deficiencies or a factor specific inhibitor may also interfere with this assay. Clinical correlation is advised.

Test results must be interpreted in their clinical context if a diagnosis of antiphospholipid syndrome is being considered. J Thromb Haemost 2006; 4: 295–306 provides consensus guidelines for diagnosis of antiphospholipid syndrome.

For detection of lupus anticoagulants, which by definition prolong a clotting time, are inhibitors, and are phospholipid dependent. Persistent presence (> 3 months) of antiphospholipid antibodies has been associated with recurrent thrombosis syndromes. A review of testing performed on UCSF patients indicates that, of all patients diagnosed with Lupus Anticoagulants, approximately 50% are detected in both Hexagonal Phospholipid Neutralization and Russell's Viper Venom tests, 25% in only the Hexagonal Phospholipid Neutralization Test, and 25% in only the Russell's Viper Venom Test.

Thrombin inhibitors (e.g. hirudin, argatroban, etc.) present in the sample to be tested may interfere in the test and lead to falsely positive results

Rivaroxaban can cause false positive results in assays used to identify LA. Evaluation for a lupus anticoagulant, therefore, cannot be accurately performed in the presence of rivaroxaban.

To monitor unfractionated heparin therapy in the presence of a lupus anticoagulant, Heparin Levels may be needed.

If unusual findings are noted a pathologist review and interpretation may be performed and separately billed for.
CPT coding 85597
LOINC code 33930-9
Last Updated 5/12/2017 9:03:32 PM
Entry Number 499
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