Dolphin  kimmyd2109 wrote over 2 years ago

Was wondering if someone could help me. My mum is on warfarin as she had blood clots in her lungs. She is currently taking 7mg and her INR is 1.7.
My friend also is on warfarin has the same INR as my mum but she is on 13.5mg.

This is worrying my mum as she doesn't understand how the dosage is worked out etc and shes concerned that maybe she is on wrong dose or even my friend could be.
I would be really grateful if someone could explain it or even tell my sites that will explain it,so i can reassure my mum that she is being treated right.

Category: Blood Clots

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Brachiosaurus  warrick - (1) - posted over 2 years ago

Hi so for a start INR is international normalised ratio, so its worked out 1.0 is a normal person not on warfarin ( this is an average time not everyone is exactly the same).
Warfarin works by preventing the liver from using vitamin K to produce fibrillin which basically is the stringy stuff in the blood that grabs the platelets when forming a blood clot. Because the liver as an organ does many other functions in your body many things can affect how much warfarin it takes to block the clotting effect to increase the amount of time it takes to form a clot. Your height , weight, age, gender, metabolism, activness, genetics are all physical factors that determine this. External factors that determine dose and cause the INR to go up or down (and hence the dose needs to be adjusted to keep the INR in range) are diet, alcohol intake, smoking, grapefruit and cranberry juice, over the counter medicines and herball supplements, antibiotics and many other medicines can interact. Also the flu, colds, diarrhea, and other infections can affect it as the liver works in your body to fight these.
So as I said INR is clotting time put into a ratio, so 1.0 is considered a time of 10 seconds (normal hence normalised), a range of INR 2.0-3.0 which is the most common, is an increased clotting time of 20-30 seconds, your blood still clots but it just takes longer. So the amount you need is the amount you need to be "in range". As an example I take 9mg daily (this can vary 0.5 mg daily up or down from week to week depending on an INR test), my father takes 3 mg daily, his cousin use to take 11 mg daily, my friends step mother takes 4 mg daily, another friend of mine takes around 7.5 mg daily. I've read of people needing up to 15 mg and higher daily to be in their range.
So tell her not to worry, that its perfectly normal for people to be on different amounts and that the main thing is that she is in her range set by her doctor :-)

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