Warfarin must be monitored to ensure it is workingeffectively and being used safely. Achieving the correct warfarininr test meters dosage can be difficult but is extremelyimportant. If the dose of warfarin is too low (thick blood), the patient is atrisk of developing harmful blood clots. If the dose of warfarin is too high(thin blood), the patient may be at risk of serious bleeding. It can bemonitored by drawing blood from a vein and sending the blood to an accreditedlaboratory to test, or it can be monitored by testing blood from a fingerstickwith an inrtest meters at home outside of a laboratory.