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When to Collect Thrombophilia Specimens

George has been communicating with Drs. Elaine Keohane (Rutgers) and Larry Smith (Abbott) about how long to wait after a thrombotic event to collect a specimen for a thrombosis risk profile. Thrombosis risk profiles include assays for antithrombin, protein C, and protein S deficiencies, which can’t be accurately measured during periods of acute inflammation (such as just after a thrombotic event), or during anticoagulation therapy. Caregivers often order profiles from inpatients who are just beginning treatment for deep venous thrombosis or pulmonary emboli; however the results  from specimens collected at thet time are consistently inaccurate. Published guidelines, usually based on the Coumadin clearance interval, usually specify 7 days, 10 days, or 14 days, however Dr. Smith found a statement in Heit J, Thrombophilia, clinical and laboratory assessment and management, in Kitchens CS, Kessler CM, Konkle BA. Consultative Hemostasis and Thrombosis, Third Edition, Elsevier, 2013 that says, “Acute thrombosis can transiently reduce the levels of antithrombin and occasionally protein C and protein S. A delay of at least six weeks after acute thrombosis…allows sifficient time for acute phase reactant proteins to return to baseline.” Our discussion led us to post a November, 2017 Quick Question “When should you perform an antithrombin, protein C, and protein S profile?.” We look forward to compiling your answers in December.

Comments (2)
Anticoagulant Therapy
Nov 8, 2017 1:57pm

In above-mentioned review
In the above-mentioned review from NEJM 2017 the time of thrombophilia testing depends on anticoagulation choice: “Do not perform thrombophilia testing while a patient is receiving anticoagulation. Instead, wait until 2 weeks after discontinuing warfarin, or 2 days for direct oral anticoagulants and heparin.” Another guideline suggests: “…perform testing following a 2–4-week period off anticoagulation, which would match the common timing for D-dimer assessment if this is also being performed to assist in decision-making…” Stevens SM, et al. Guidance for the evaluation and treatment of hereditary and acquired thrombophilia. J Thromb Thrombolysis. 2016; 41: 154–164.

Nov 7, 2017 4:40pm

Recent hospitalist’s point of
Here is a recent hospitalist’s point of view: “…it is no longer appropriate or wise to allow unfettered access to thrombophilia testing in hospitalized patients… De-implementation efforts that provide hard stops, education, and limited access to such testing in the electronic medical ordering system when ordering thrombophilia workups now appear necessary.”

from Heidemann LA, Petrilli CM, Barnes GD. Inpatient thrombophilia testing: at what expense? J Hosp Med. 2017;12:777–8.
Another recent point of view from NEJM: Most patients with venous thromboembolism do not require thrombophilia testing, since the results will not affect management. Testing may be considered in younger patients with weak provoking factors, a strong family history, or recurrence at a young age. Connors JM. Thrombophilia testing and venous thrombosis. N Engl J Med. 2017;377:1177–87.

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