Prothrombin

Test Code

CPT Codes
85303

Includes

INR

Preferred Specimen

1 Sodium Citrate Plasma Blue

Minimum Volume

Blue top must be filled to Minimum Fill Indicator Line on tube.

Other Acceptable Specimens

none

Instructions

Outreach clients should spin the blue top, remove the plasma, and freeze in a polypropylene tube.

Transport Container

BLUE, polypropylene tube

Transport Temperature

Blue - RT; polypropylene - frozen

Specimen Stability

Blue - 24 hours RT; Plasma - 24 hours RT, 2 weeks frozen

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Sample must be free of clots and hemolysis.

Methodology
Electromagnetic Viscosity Detection

Setup Schedule

Daily on Receipt

Report Available

Upon Completion of Analysis

Reference Range

12.0 - 14.6 Seconds

Clinical Significance

The Prothrombin time is a basic coagulation screening test for the assessment of congenital ans acquired deficiencies of the extrinsic pathway (factors II, V, VII, X). The prothrombin time can be prolonged in certain clinical states, i.e. warfarin therapy, intestinal reabsorption disorders, liver failure, fibrinolysis and DIC. The prothrombin time is also used to monitor warfarin therapy because of its sensitivity to variations in the concentration of the vitamin-K dependent factors of II, VII and X. Because of the variations in the prothrombin time results with different thromboplastins and instruments, it is recommended that the prothrombin time results be converted to an INR. The INR corresponds to the value of the ratio of the patient's PT and the geometric mean PT of the normal reference population.

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.