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Thrombin Time : 1000916
MessageThe aliquot must remain frozen. Freeze thaw cycle will adversely affect specimen integrity. CRITICAL FROZEN: Separate specimens must be submitted when multiple tests are ordered.
Test Code
TT or 1000916
Alias/See Also
TT (Thrombin Time)
CPT Codes
85670
Instructions
Blue top tube, 3.2% sodium citrate.
• Obtain venous blood by clean venipuncture. Avoid slow-flowing draws and/or traumatic venipunctures as either of these may result in an activated or clotted specimen. Do not use needles smaller than 23 gauge. Do not leave the tourniquet on for an extended length of time before drawing the sample.
• A pilot tube (non-additive or light blue tube) before drawing coagulation specimens in light blue vacuum tubes is only necessary when using a butterfly blood collection set as this will cause reduced draw volume in the first tube. Discard the pilot tube.
• Fill light blue tubes as far as vacuum will allow and mix by gentle inversion. Exact ratio of nine parts blood to one part anticoagulant must be maintained. Inadequate filling of the sample tube will alter this ratio and may lead to inaccurate results. Patients who have hematocrit values above 55 percent should have the anticoagulant adjusted to maintain the 9:1 ratio. Use the following formula to determine the amount of anticoagulant to use: [(100 – Hct) / (595 – Hct) ]* total volume = amount of anticoagulant required.
• After collecting the blood, examine the tube to ensure that it is filled to within 90% of the fill line.
• Note: Specimens containing heparin should not be used for coagulation studies. If possible, stop heparin therapy before the draw to avoid contamination. Heparin interferes with most clotting assays. If heparinized line must be used to obtain the sample, flush line with 5mL saline and discard the first 5 mL of blood drawn into a syringe, or 6 “dead space” volumes of the line.
• Obtain venous blood by clean venipuncture. Avoid slow-flowing draws and/or traumatic venipunctures as either of these may result in an activated or clotted specimen. Do not use needles smaller than 23 gauge. Do not leave the tourniquet on for an extended length of time before drawing the sample.
• A pilot tube (non-additive or light blue tube) before drawing coagulation specimens in light blue vacuum tubes is only necessary when using a butterfly blood collection set as this will cause reduced draw volume in the first tube. Discard the pilot tube.
• Fill light blue tubes as far as vacuum will allow and mix by gentle inversion. Exact ratio of nine parts blood to one part anticoagulant must be maintained. Inadequate filling of the sample tube will alter this ratio and may lead to inaccurate results. Patients who have hematocrit values above 55 percent should have the anticoagulant adjusted to maintain the 9:1 ratio. Use the following formula to determine the amount of anticoagulant to use: [(100 – Hct) / (595 – Hct) ]* total volume = amount of anticoagulant required.
• After collecting the blood, examine the tube to ensure that it is filled to within 90% of the fill line.
• Note: Specimens containing heparin should not be used for coagulation studies. If possible, stop heparin therapy before the draw to avoid contamination. Heparin interferes with most clotting assays. If heparinized line must be used to obtain the sample, flush line with 5mL saline and discard the first 5 mL of blood drawn into a syringe, or 6 “dead space” volumes of the line.
Transport Container
Blood collected in 3.2% sodium citrate (light blue top tube). Proper blood to anticoagulant ratio is required. The tubes must be at a 100 ± 10% fill volume to maintain the correct ratio. Centrifuge light blue-top tube at 1500 g for no less than 15 minutes or speed/time to consistently yield platelet-poor plasma (<10,000/µL). Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer, and place into a plastic transport tube (Min. 0.5 mL). Immediately freeze the aliquot and ship on dry ice.
Transport Temperature
Frozen.
Specimen Stability
After separation from cells: Ambient: Unacceptable; Refrigerated: Unacceptable; Frozen: 14 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Marked hemolysis; marked icterus; marked lipemia; received thawed; received refrigerated; received room temperature
Methodology
Clotting
Setup Schedule
Sunday - Saturday
Report Available
1 day
Reference Range
<12 years: Not established
>= 12 years: 14.0 – 24.0 seconds
>= 12 years: 14.0 – 24.0 seconds
Clinical Significance
The determination of the thrombin time using is suitable for:
Monitoring heparin therapy using high-molecular-weight heparin; Monitoring fibrinolysis therapy;
Screening for disorders of fibrin formation and in cases of suspected severe fibrinogen deficiency states;
Differentiating between a heparin-induced prolongation of the thrombin time and fibrin formation disorders.
Prolonged thrombin times are measured both in patients with disorders of fibrin polymerization as well as during heparin treatment.
Thrombin converts the fibrinogen in the plasma sample into fibrin, thus producing a fibrin clot. The time taken for the fibrin clot to form is measured.
Monitoring heparin therapy using high-molecular-weight heparin; Monitoring fibrinolysis therapy;
Screening for disorders of fibrin formation and in cases of suspected severe fibrinogen deficiency states;
Differentiating between a heparin-induced prolongation of the thrombin time and fibrin formation disorders.
Prolonged thrombin times are measured both in patients with disorders of fibrin polymerization as well as during heparin treatment.
Thrombin converts the fibrinogen in the plasma sample into fibrin, thus producing a fibrin clot. The time taken for the fibrin clot to form is measured.
Performing Laboratory
med fusion
