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Test Code APTT or LAB325 Partial Thromboplastin Time (APTT), Blood

Important Note

Please contact the laboratory if the patient's hematocrit is over 55%, as a special tube must be provided for the blood draw.

Specimen Requirements

Specimen Type:

Whole Blood

Container Type:

Blue top: 2.7 mL or 1.8 mL

Optimal Collection Volume:

  • 2.7 mL in solid blue top tube or 1.8 mL in clear blue top tube.  The correct fill volume is indicated by the etched line on the tube.
  • Click here to view the specimen collection guide for blue top (citrate) tubes.

Collection Instructions:

  1. Gently invert 5 to 10 times to mix blood.
  2. If collected through a blood collection set (butterfly), a discard tube must first be drawn to eliminate dead space from tubing.  

Specimen Transport Temperature:

  • Room temperature for up to 4 hours. If testing is delayed, separate plasma and freeze (see outpatient collection instructions below).
  • Specimens cannot be refrigerated

Processing Instructions:

  1. Centrifuge sample within 4 hours of collection. Platelet-poor plasma must be obtained per laboratory procedure.
  2. If testing will be delayed >4 hours from collection, aliquot plasma into a separate vial and freeze immediately.

Outpatient collections

  1. Spin down the sample, remove plasma, and spin plasma again to obtain platelet-poor plasma.
  2. Separate the platelet-poor plasma into a screw-top vial.
  3. Freeze plasma immediately.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Specimen Stability

Specimen Type

Temperature

Time

Whole blood

Room Temperature

4 hours

Platelet Poor Plasma

Room Temperature

4 hours

Platelet Poor Plasma

Frozen at - 20 C

2 weeks

Specimen Rejection Criteria

  • Tube underfilled
  • Refrigerated specimen
  • Clotted specimen
  • Specimen not processed within four hours of collection

Useful For

Monitoring and regulating heparin therapy.

Methodology

ACL TOP - Coagulometric (Turbidimetric)

Reference Ranges

Test ID

Reference Range and Reporting Units

APTT

25-39 seconds

 

Heparin Therapeutic Range

Cardiac/Neuro

DVT/PE

50-65 seconds

55-85 seconds

Critical Value: ≥ 105 seconds

Day(s) Performed

24/7

Expected TAT

Same day

Performing Laboratory

Bronson Laboratory, Coagulation - Kalamazoo, Battle Creek, Paw Paw, South Haven

Sample Retention Time

48 hours

CPT Code

85730

LOINC Code

14979-9