PROTIME

Mnemonic

PT

Synonym

PT-INR - PT - Protime - Prothrombin Time - International Normalized Ratio

Specimen Collection Requirements

Collect

Plasma, one light blue (3.2% Buffered Sodium Citrate) top tube

Handling

DO NOT refrigerate. See Coagulation Specimen Collection Guidelines. for more information.

Preferred Volume

If frozen, 1.0 mL aliquot

Minimum Volume

If frozen, 0.5 mL aliquot

Transport

Ambient

Rejection Criteria

Clotted samples, samples collected in containers other than 3.2% Buffered Sodium Citrate, tubes filled less than 90%, over-filled tubes, samples from patients with a Hematocrit greater than 55% (if abnormal), hemolyzed samples due to ex-vivo causes (i.e., difficult draw, poor sample draw). Refrigerated specimens. 

Stability

WHOLE BLOOD Ambient: 24 hours PLASMA Ambient: 4 hours; Frozen: -20°C 2 weeks, -70°C 6 months; OPEN TUBE: 4 hours ambient

Testing Information

Performed

7 days/week

Method

Clotting

Referral Lab

Samaritan Health Services Laboratories

Reference Values

Reference Values

Varies, see report.

Critical Values

INR: ≥5.0

Therapeutic Range

THROMBOSIS/EMBOLISM: 2.0-3.0 BILEAFLET MECHANICAL VALVE IN AORTIC POSITION: 2.0-3.0 MECHANICAL PROSTHETIC VALVES (HIGH RISK): 2.5-3.5

CPT Codes

85610

Last Updated: Wednesday, April 15, 2020 09:38:15 AM