Specimen Collection Manual and Test Catalog

1 mL

• If the patient’s hematocrit (HCT) is >55%, the volume of anticoagulant in the tube must be adjusted. Contact a performing location for sodium citrate adjusted tubes or instruction for how to adjust the sodium citrate.
• When possible, use fresh venipuncture.
• Avoid prolong tourniquet time (< 1 minute) and hemolysis during collection as this will alter results.
• If indwelling catheter or butterfly collection device must be used, draw sample from a non-heparinized lumen or flush the line with 5 mL of saline and discard the first 10 mL of blood.
• Tubes should be >90% filled.
• Immediately mix gently after collection by inverting the tube end over end 5 to 6 times. Avoid vigorous mixing or additional inversion. Observe for the presence of clots or hemolysis and recollect if observed.

Analysis < 24 hours: No processing. 
Analysis =/> 24 hours: Centrifuge specimen immediately at designated time and speed to obtain platelet-poor plasma (<10,000/µL). Using a plastic pipette, carefully remove plasma from cells, avoiding platelet/buffy layer by leaving a thin layer of plasma on top the cells. The centrifuged plasma should be aliquoted (1 mL per aliquot) into clearly labeled polypropylene tubes. The number of tests ordered will determine the aliquots needed. Check the residual specimen for clot and if present discard sample and redraw specimen. If plasma is icteric, lipemic or hemolyzed a lab comment should be generated to notify staff. Freeze upright in non-thaw freezer.

Whole blood: Room temperature 
Plasma: Frozen on dry ice

Room temperature: 24 hours 
Frozen -20°C: 2 weeks 
Frozen -70°C: 6 months

Clotted, hemolyzed, improperly filled tubes, improper anticoagulant ratio (HCT >55% and citrate not adjusted), refrigerated specimens, or stability exceeded.

Note: Specimen suspected of thawing in transport, indicated by slant in aliquot or specimen in lid of tube, will have testing performed, and the comment “interpret results with caution as thawing suspected” added to results.

PT 11.6 – 15.2 
INR 0.8 – 1.2

Anticoagulation Impact on Coagulation Tests

PT, INR

INR, PTINR, Protime, Prothrombin Time, International Normalized Ratio

Screening test used to assess the extrinsic and common clotting pathways. Prolonged PT may be associated with bleeding and could indicate one or more deficiencies of plasma factors VII (most common), X, V, II, and fibrinogen (only if less than 100 mg/dL), and/or a possible inhibitor (factor dependent or lupus anticoagulant) as well as a vitamin K deficiency (from dietary or intestinal reabsorption disorders). Diseases often associated with prolong PT include liver failure and disseminated intravascular coagulopathy (DIC).

Medications may also prolong PT including warfarin, direct thrombin inhibitors, direct Xa inhibitors, vitamin K antagonist and antibiotics that prevent vitamin K absorption. An INR is the standardized measurement used to monitor warfarin.

Warfarin Therapeutic Ranges: 
INR: 2.0-3.0 conventional anticoagulation
INR: 2.5-3.5 high intensity anticoagulation.

If patient has a lupus anticoagulant and a prolong PT, the INR may not be accurate and an alternative test for monitoring warfarin should be considered.