INR = International Normalized Ratio
This is a calculated number based on a test for the time it takes your blood to clot. For normal, everyday, walking-around-healthy humans, this number should be around 1.0, but could be in the range of 0.8 to 1.2. The lower the number, the faster the blood will clot. This number will vary in that range on a day-to-day basis for everyone depending on their diet, liquid intake, and a number of other factors. If a normal, everyday, walking-around-healthy person had an INR of over 1.5 (or under 0.8), their doc would definitely start paying attention.
For people with "clotting issues," this number needs to be driven higher with medications. Examples:
- As folks get older (and more sedentary and less cardiovascular and have more clogging in their arteries), they are more likely to develop blood clots. These could be in the form of Deep Vein Thrombosis (DVT) from sitting on that long drive or long flight to visit their grandkids or just sitting in their recliner feeling generally crappy for a few hours. This is why most docs have their elder patients start taking "baby aspirin" (81 mg) daily, because aspirin has an anticoagulant effect for protection from clots. The smallest of clots that get to the heart will cause a heart attack or, if they get to the brain, will cause a stroke.
- Folks with specific medical conditions such as Atrial Fibrillation (AF, like Rader Bob has experienced a few times) will be prescribed a stronger anticoagulant like Coumadin (aka Warfarin or "Rat Poison") to get their INR up into the 2.0 to 3.0 range. (AF tends to cause clots to form in the atrium because the blood is not being actively moved through the system.)
- Folks who have had heart attacks or bypass surgery will also be prescribed with anticoagulants to keep their INR up around 2.5 to 3.5.
- People with mechanical hearts will be given strong anticoagulants to keep their INR up around 4.0. (The mechanical heart is more likely to damage blood cells and induce clotting.)
So, with Rader Bob's history of AF and his INR down at 1.1, his doc has asked him to increase his dosage of Rat Poison and to get his INR checked again in two weeks.
Hope that helps!
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