The result needs to be taken in context of recent INR measurements and dose changes. An INR result higher than the desired range means the blood is “too thin”. Blood plasma normally takes between 11 and 13.5 seconds to clot if youre not taking blood-thinning medication. The Prothrombin time of a normal sample of bloodĪ result of 1.0, up to 1.5, is therefore normal.Ī low INR result means your blood is ‘not thin enough’ or coagulates too easily and puts you at risk of developing a blood clot.Ī high INR result means your blood coagulates too slowly and you risk bleeding.Īn INR lower than the desired range means the blood is “not thin enough” or clots too easily.It is important that the tube is filled to the correct level, otherwise false results may occur. PT measures factors II, V, VII, X and fibrinogen. The reference range for prothrombin time is usually around 12-15 seconds the normal range for the INR is 0.8-1.2. The INR test is a blood test and requires a small tube of blood from a vein – approximately 4 millilitres. They are used to determine the clotting tendency of blood, in the measure of warfarin dosage, liver damage and vitamin K status. Artificial heart valves of the mechanical type – because of the risk of a clot forming on the valve and causing a blockage in the heart.Some cases of Heart failure (Left Ventricular, and Congestive Cardiac Failure), especially when the heart is enlarged as in some forms of cardiomyopathy.

Atrial Fibrillation (AF) – an irregular heartbeat, sometimes accompanied by an enlarged left atrium – both of which predispose to the formation of blood clots in the heart, which may embolise to the blood vessels of the brain causing a cerebral infarction, a stroke – also known as a CerebroVascular Accident (CVA).

Pulmonary Embolism (PE) – a clot in the lung, that has travelled through the veins (“embolised”) from a DVT formed elsewhere, such as the deep veins of the leg or pelvis.

Deep Vein Thrombosis (DVT) – a clot in a deep vein, commonly of the leg.In relation to liver function tests – liver dysfunction can lead to decreased production of certain clotting factors.Monitoring as a part of warfarin therapy Applies to the following strengths: 4 mg 1 mg 2 mg 5 mg 7.5 mg 10 mg 2.Be aware that foods containing vitamin K can affect Coumadin therapy. Typical maintenance doses are from 2 to 10 mg/day. If a patients CYP2C9 and VKORC1 genotypes are not known then the initial dose of Coumadin is usually 2 to 5 mg once daily. The most common reasons for an INR test are: An INR of 2.5 (range 2.0 to 3.0) is recommended for most indications.

Pt inr normal range on warfarin