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Prothrombin Time/Anticoagulation Monitoring

What are Anticoagulation Medicines?

Children with some kinds of heart problems must take anticoagulation medicines. These medicines, sometimes called blood thinners, decrease the risk of problems caused by blood clots. There are several different types of anticoagulation medicines and all of them reduce the body's ability to make blood clots. The most common reason children need anticoagulation medicine is because they have an artificial heart valve. Harmful clots can form on this valve which block the blood flow across the valve or could travel elsewhere in the body. Children whose blood flow through the heart is slower than normal may also be placed on an anticoagulation medicine. Finally, some children with heart rhythm problems need this type of medicine. The two most common medicines used for anticoagulation are aspirin and Coumadin (KOO-mah-din). Children taking aspirin do not require any special monitoring.

What is a Prothrombin Time Test?

Children who are taking Coumadin must have their blood tested regularly to make sure that the dose of medication is appropriate. The dose must be high enough to protect the child from developing harmful clots but not so high that the child is at risk for serious bleeding. The blood test is called a prothrombin (pro-THROM-bin) time and measures how much the clotting system has been affected by the medicine. When a child is first started on Coumadin, the prothrombin time must be checked once or twice a week. When it is clear that the dose of Coumadin is safe, the blood test can then be done once a month. Since close monitoring of prothrombin times is so important for children taking Coumadin, we have an anticoagulation monitoring program. The service is provided by a clinical nurse specialist who follows the child's prothrombin time results along with the cardiologist.

If any dosage changes are needed, she will contact the family directly. If the blood work is overdue, the family may receive a reminder phone call or a letter. In addition, the clinical nurse specialist can answer questions about anticoagulation medicines. The prothrombin time can be drawn by most health facilities and the results sent to the Pediatric Cardiology Clinic for evaluation and follow-up. You will need to choose the laboratory that you will be using regularly, and let us know their address and phone number so that we can make the necessary arrangements with them. At the clinic, the prothrombin time can be done by a finger poke method. This is helpful for babies or children from whom it is very difficult to get blood by poking a vein. Prothrombin times can be affected by other medications or major dietary changes that the child requires. Whenever your child is started on a new medicine, goes to the dentist, or requires a surgical procedure, make sure that the doctor knows that your child is taking Coumadin.

What if I have questions?

If you have additional questions you may contact the Michigan Congenital Heart Center at the University of Michigan at (734) 764-5176.

2006: Information reviewed and approved by Laura Bell, RN, MSN, PNP Pediatric Cardiac Surgery and Lynda Dettling RN, BSN.


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