Prothrombin time (PT) is the sole test used to measure the effectiveness of coumarin-type anticoagulant drugs, such as warfarin sodium (Coumadin). The most common methods to report the PT are the clotting interval (in seconds) and the International Normalized Ratio (INR). Targets for the INR vary, depending on the reason for anticoagulation. For example, a patient having hip surgery, who is being anticoagulated to prevent deep vein thrombosis, may have a target INR of between two and three. To prevent arterial thrombosis in a patient with an artificial heart valve, the INR therapeutic goal may be in the 2.5- to 3.5-range.
Several medical manufacturers have gained CLIA-waived status for their PT test devices, allowing rapid assessment in the point of care setting, and, in the cases of several waived-devices, in the patients home as well.
Roche Diagnostics Corporation, Indianapolis, Ind., a division of Swiss F. Hoffmann-La Roche Ltd, produces the CoaguChek S System, designed for health care professionals to enable on-the-spot analysis of coagulation levels during mobile emergency treatment, in hospital and in general practice. The device employs electromagnetic field kinetics to determine PT. A single d