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Test Code LAB325 Partial Thromboplastin Time (PTT), Plasma

Important Note

Alternative anticoagulants which directly inhibit thrombin (I.V.; Argatroban, Bivalirudin: Oral; dabigatran) positively interfere with APTT (e.g. direct thrombin administered concurrently with LMWH or UFH can produce a falsely elevated APTT).

Performing Laboratory

Barnes-Jewish Hospital Laboratory

Methodology

Absorbance measurement, Clot signature formation
Literature References:
HemosIL SynthASil (pn 20006800) package insert issued 02/2016, Instrumentation Laboratory.

Specimen Requirements

Specimen Type: Plasma

Container/Tube: Light-blue top (citrate)
Specimen Volume: Full tube
Specimen Minimum Volume: Full tube
Collection Instructions:

  1. Draw a discard blue top tube prior to drawing a light-blue top (citrated) tube if using a Winged Infusion Set.  Discard tube should be under filled and discarded.
  2. Clotted blood or an insufficient specimen is not acceptable.
  3. Avoid phlebotomy techniques which cause hemolysis and heparin contamination.
  4. Follow nursing policy on volume of blood to discard prior to collecting blood from indwelling heparinized catheters.

Analyte Stability:

4 hours at 18° C to 24° C


Additional Information: If the patient is a hospital patient and the hematocrit is >55%, call Barnes-Jewish Hematology Laboratory at 314-362-5203 for instructions.

Day(s) Test Set Up

Monday through Sunday

Turnaround Time:

STAT: 1 hour after receipt in laboratory

Routine: 2-4 hours after receipt in laboratory

Test Classification and CPT Coding

85730

Reference Values

28 - 38 seconds

Physician alert value (automatic call-back): >150 seconds

Specimen Transport Temperature

Ambient/Refrigerate NO/Frozen NO

Additional Information

For BJH Laboratory Use Only
Analyte Stability:

4 hours at 18o C to 24° C


Laboratory Processing Instructions:

Test performed in BJH Core Lab.

LOINC Code Information

Name LOINC Code
Activated Partial Thromboplastin Time 14979-9