Test Name

Prothrombin Time

Test Code

151

Unit

Seconds (sec)

Station

Coagulation

Synonym Name/Abbreviation

PT; Protime

CPT Code

85610

Performing Facility

American Medical Labs, Herzliya
Pituah

Analyzer

Siemens, Sysmex CA1500

Test Method

Photo-optical

AML Preferred Tube

Blue top Na-Cit 3.2%

Collection/Storage
Instructions

Collection tubes must be filled to completion to ensure a
proper blood to anticoagulant ratio. The sample should be mixed
immediately by gentle inversion at least six times to ensure adequate
mixing of the anticoagulant with the blood. When noncitrate tubes are
collected for other tests, collect sterile and nonadditive (red top) tubes
prior to citrate (blue top) tubes. Any tube containing an alternate
anticoagulant should be collected after the blue-top one. Gel-barrier
tubes and serum tubes with clot initiators should also be collected after
the citrate tubes. Centrifuge and carefully remove the plasma using a
plastic transfer pipette. Transfer plasma into a transport tube and send
refrigerated to laboratory. Stability: up to 24h at 18 to 24
^oC; frozen 2 weeks at -20^oC; -70^oC up to
6 months.

Min. Volume

1 mL Plasma

Comments

Values obtained with different assay methods should not be
used interchangeably in serial testing. It is recommended that only one
assay method be used consistently to monitor each patient’s course of
therapy.

Turn-Around-Time

One day

Intended Use

Control of dosage in
of coumarin derivative therapy. Evaluation of extrinsic coagulation
system; aid in screening for congenital deficiencies of factors II, V,
VII, X.

Limitations

A large number of medications modify the hypoprothrombinemic
action of coumadins, including (but not limited to) Salicylates,
phenylbutazone, clofibrates, barbiturates, chloral hydrate,
chloramphenicol, ethchlorvynol, glutethimede, phenyramidol, quinidine,
allopurinol, anabolic steroids, MAO inhibitors, nortriptyline, phenytoin,
propylthiouracil, antiacids, sulfonamides, carbamazepine, estrogenic
contraceptives, griseofulvin.

Result is sensitive to plasma:citrate anticoagulant ratio,
meaning if enough blood is not added to the liquid citrate-containing tube
when the specimen is drawn, an erroneous PT result may be yielded. Do not
draw blood from an arm with a heparin lock or heparinized catheter; If
testing is ONLY for PT & PTT, draw “dead space” into an empty tube
first and discard before collection into Na-Cit
tube.

Patient Preparation

No patient preparation
needed.

Reasons for Rejection

Clotted specimens; Gross lipemia;  or hemolysis; tube <90% full;
improperly labeled specimen.

Adult Reference Ranges

 9.0 to 12.2
sec