What does the international normalized ratio (INR) assess?

The international normalized ratio (INR) assesses how long it takes for blood to clot. It is primarily used to monitor patients on anticoagulant therapy, such as warfarin, to ensure they are within a therapeutic range that minimizes the risk of clotting or bleeding. The INR provides a standardized way to measure the prothrombin time (PT), which is the time it takes for blood to clot, regardless of the testing methods used by different laboratories.

Monitoring the INR is crucial in clinical practice to adjust medication dosages appropriately and manage patient care effectively. It allows healthcare providers to balance the effectiveness of anticoagulation therapy and maintain safety in patients at risk of thrombotic events.

Other options, while related to blood and health, do not pertain to the specific function of the INR. Blood glucose levels are measured by other tests, blood pressure regulation relates to cardiovascular function not assessed by INR, and hydration levels are evaluated through different means such as electrolyte balance and osmolality tests.