Partial Thromboplastin Time

General Information

Lab Name

Lab Code

PTT

Epic Name

Partial Thromboplastin Time

Description

Partial Thromboplastin Time (PTT) is a screening test for the assessment of congenital and acquired deficiencies of the intrinsic (factors VIII, IX, XI and XII) and common (factors II, V, X and fibrinogen) pathway coagulation factors. It is also used to detect the presence of coagulation inhibitors such as lupus anticoagulant and specific factor inhibitors. PTT can be used to monitor unfractionated heparin therapy although Anti-Xa for Heparin Infusion (HIXA) is the preferred test for heparin monitoring.

Synonyms

aPTT

Components

Code	Name
PTTPAT	PTT Patient
PTTXM	PTT X_Mean

Interpretation

Method: Clot based
Reference Range: See individual components
Ref. Range Notes: For information regarding the use of this test for anticoagulant monitoring, visit UW Medicine Anticoagulation Services

Ordering & Collection

Specimen Type: Blood
Collection: 2, 3 or 5 mL BLUE TOP (CITRATE) tube

Pediatric draws: (At UW-MT ONLY) Contact the lab at 598-6242 and ask for a baby draw tube for coagulation testing.

Note: Blood dilution and contamination with heparin are risks if specimen is collected from an arm with indwelling catheter. If arm must be used, turn off the IV for NO LESS THAN 5 MINUTES before performing a peripheral draw.

If sample is collected through the catheter, turn off the IV, flush the catheter with saline and discard a waste sample before drawing the sample for the PTT. (See Nursing Policies and Procedures for details.)
Handling Instructions: UW-MT/HMC: For Heparin monitoring on inpatients, specimen MUST be processed within 1 hour.

All other PTT requests, process within 6 hours of blood collection.

UW-NW only: specimens MUST be processed within 4 hours of blood collection.

FHCC: Specimens must be processed within 4 hours of collection.
Quantity: Requested: entire specimen
Minimum: 1.0 mL Citrated plasma

Processing

Receiving Instructions: Take specimen to Coag

Outside Laboratory: Centrifuge for 10 minutes, remove plasma & re-spin plasma for another 10 minutes. Decant & Freeze plasma (minimum 1.0 mL) @ -20°C to -80°C. Send Frozen on dry ice.

Stability: plasma samples frozen at -70°C or below are good for 1 year

Misc Sendout

Performance

Lab Department

Coagulation(COAG)

Frequency

Daily

Available STAT?

Yes

Performing Location(s)

HMC	Coagulation 206-520-4600 325 9th Ave, Rm # GWH-47, Seattle, WA 98104-2420
UW-NW	Main Lab 206-668-1344 UW Medical Center – Northwest 1550 N 115th Street, A200 Seattle, WA 98133
FHCC	Fred Hutch Alliance Lab 206-606-1088 825 Eastlake Ave, Seattle, WA 98109
UW-MT	Coagulation 206-520-4600 Clinical Lab, Room NW220, University of Washington Medical Center, 1959 NE Pacific street, Seattle, WA 98195

Billing & Coding

CPT Codes: 85730
LOINC: 14979-9
Interfaced Order Code: UOW4815