Synonym/Acronym:
Protime, PT.

Common Use:
To assess and monitor coagulation status related to therapeutic interventions and disorders such as vitamin K deficiency.

Specimen:
Plasma (1 mL) collected in a completely filled blue-top (sodium citrate) tube.

Normal Findings:
(Method: Clot detection) 10 to 13 sec.

• International normalized ratio (INR) = Less than 2 for patients not receiving anticoagulation therapy, 2 to 3 for patients receiving treatment for venous thrombosis, pulmonary embolism, and valvular heart disease.
• INR = 2.5 to 3.5 for patients with mechanical heart valves and/or receiving treatment for recurrent systemic embolism.