Lab Dept:


Test Name:


General Information

Lab Order Codes:



APTT to Fairview University; Partial Thromboplastin Time to Fairview University; Activated PTT to Fairview University

CPT Codes:

85730 – Thromboplastin time, partial (PTT); plasma or whole blood

Test Includes:

PTT result reported in seconds.


Test Indications:

Useful for screening of the intrinsic and common pathways in the coagulation system (factors II, V, VIII, IX, X, XI and XII); screening for dysfibrinogenemia, disseminated intravascular coagulation (DIC), congenital hypofibrinogenemia, vitamin K deficiency, HMWK deficiency and prekallikrein deficiency

Lab Testing Section:

Coagulation - Sendouts

Referred to:

Fairview University Medical Center

Phone Numbers:

MIN Lab: 612-813-6280

STP Lab: 651-220-6550

Test Availability:

Daily, 24 hours

Turnaround Time:

8 hours routine; 4 hours STAT

Special Instructions:

Patient should not be receiving Coumadin® or heparin.

If so, this should be noted on the request form. Heparin or warfarin therapy can affect certain coagulation factors or assays, preclude their performance, or cause spurious results.

Indicate when specimen is drawn from a line or a heparin lock. Deliver immediately to the laboratory.


Specimen Type:

Whole blood


Light Blue top (Buffered Na Citrate 3.2%) tube

Draw Volume:

2.7 mL blood in a 3 mL tube (Minimum: 1.8 mL in a 2 mL tube)

Processed Volume:

Specimens will be processed at reference lab facility if received within 4 hours of collection. Otherwise, specimens need to be processed at referring facility and provide minimum of two 0.5 mL specimens frozen at -70. Follow directions below under Special Processing


A clean venipuncture is essential. Do Not use the first 2 mL of blood collected.

If the patient’s hematocrit is >55%, contact the laboratory to obtain a special tube.

Fill tube completely. Mix thoroughly by gentle inversion.


Special Processing:

Lab Staff: Do Not centrifuge. Do Not freeze. Send to reference lab in original Vacutainer® at room temperature if within 4 hours of collection. Forward promptly.

If specimen is >4 hours old prior to shipment, process specimen as follows: Spin sample collected in blue top tube(s) for 5 minutes on the Stat Spin centrifuge, remove plasma and transfer to a 4 mL BCS sample cup(s), spin remaining plasma again for 5 minutes in the Stat Spin Centrifuge. Transfer plasma into two labeled 10x75 mL plastic tubes with a minimum of 0.5 mL in each. Freeze at -70 and send specimens on dry ice to Fairview University.

Patient Preparation:


Sample Rejection:

Improper tube; clotted sample; overfilled tube; underfilled tube; mislabeled or unlabeled specimens


Reference Range:


Range (Seconds):

0 – 1 month:

27 - 52

1 – 6 months:

24 - 47

>6 months:

22 - 37

Critical Values:

>105 seconds




Activated partial thromboplastin time


Patient on heparin therapy


Fairview University Medical Center Web Page February 2014

Harmening DH (1997) Clinical Hematology and Fundamentals of Hemostasis


6/3/2004: Reference ranges previously ≥1 yr = 23.0 – 33.0 seconds, current ranges broken down by age under Reference Range:
Critical value changed from >70 seconds to >105 seconds.
Draw volume changed from 4.5 mL to 2.7 mL blood. Minimum Draw Volume changed from 2.7 mL to 1.8 mL blood.
5/25/2010: Tubing patient specimens is no longer prohibited.
2/25/2014: Fairview specimen processing update.