Name: Thrombin Time Inhibitor Screen
Test Name: Thrombin Time Inhibitor Screen
Health Link Test Code: HCTTIS
LIS Test Code: TTIS
CPT Code(s): 85670x2
Methodology: Photo-Optical Clot Detection
Also known as a "mixing study". An inhibitor screen is done to explain a prolonged Thrombin Time.
Days Performed: Mon-Fri, dayshift - day varies. Specimens are accepted at any time. Testing required during off hours must be approved by a Coagulation physician. Call 263-5005 before collection.
In-Lab Turnaround Time: 4 - 10 days.
Stat In-Lab Turnaround Time: 1 day.
Patient MUST be off heparin for at least 72 hours and off direct thrombin inhibitor for 24 hours prior to specimen collection.
Collection Container: Light blue top (3.2% NaCitrate)
Do NOT draw through a line containing heparin. The venipuncture MUST be atraumatic to avoid hemolysis and contamination with tissue factors and platelets. Tube must be allowed to fill completely.
Please indicate patient history and if patient is receiving anticoagulant (Coumadin/Heparin/Vitamin K antagonist), direct thrombin inhibitor or fibrinolytic agent therapy and duration.
Collection Volume: Four full 3.5 mL tubes
Pediatric Collection Volume: 2 full pediatric tubes filled to mark
4 hours on a spun tube
2 weeks at -20°C; 6 months at -70°C
Sample Analyzed: Plasma
Testing Volume: 5 mL
Pediatric Testing Volume: 1.5 mL
Ultracentrifuge sample and label "ULT". If an ultracentrifuge is not available, centrifuge tube to obtain platelet poor plasma (platelet count should be 10 K/uL or less). Separate plasma from cells and transfer to plastic tube and spin again. Transfer plasma from second spin to clean plastic tube or vial. Indicate on tube "spun twice". Freeze plasma within 4 hours of collection at -20°C or below.
Transport whole blood specimen at room temperature to UWHC Laboratory within 4 hours of collection. See Specimen Processing for instructions if transport criteria are not met. Transport frozen plasma aliquot on dry ice to UWHC Hospital Laboratory.
Hemolyzed specimens, clotted specimens, partially filled tubes and whole blood specimens greater than 4 hours old when received by the laboratory are not acceptable.
18 years and up: Negative for an inhibitor
Interpretation Type: Reference Interval
The presence of an inhibitor can be ascertained by performing a Thrombin Time before and after the incubation of a 1:1 mixture of patient plasma and normal plasma.