An outpatient on Coumadin comes to the laboratory for a PT. He had been in the hospital 6 weeks earlier for treatment of deep vein thrombosis (DVT).
PT: 18.0 sec
Thromboplastin International Sensitivity Index (ISI): 1.2
The geometric mean of the PT reference interval: 12 (for this laboratory)
Question 1: Interpret the results.
A) PT Prolonged
B) PT and aPTT prolonged
C) Factor inhibitor present
D) Factor deficiency
Question 2: Calculate the patient's INR
A) 1.8
B) 2.3
C) 1.6
D) 1.0