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Test Code PTT Activated Partial Thromboplastin Time (APTT), Plasma

Additional Codes

Ordering Mnemonic



Photo-Optical Clot Detection

Performing Laboratory

Holland Hospital Laboratory Services

Specimen Requirements

Container/Tube: Light blue-top (3.2% sodium citrate) tube-Clotted blood is not acceptable.

Specimen Volume: Full tube of whole blood

Collection Instructions: Invert 6 times to mix blood.

Note: Centrifuge and separate plasma within 4 hours of draw. Send specimen in plastic vial.

Specimen Transport Temperature

Ambient <4 hours

Day(s) Test Set Up

Monday through Sunday

Available STAT

Test Classification and CPT Coding


Reference Values

Normal: <35 seconds

An APTT therapeutic range of 60-99 seconds corresponds to a heparin therapeutic level of 0.3-0.7 IU/mL.

Critical value (automatic call-back): ≥150 seconds