You should have regular blood tests for the whole time you are taking azathioprine or mercaptopurine. You will need full blood count (FBC), and liver function tests (LFT), measuring levels of liver enzymes. Both tests are important because azathioprine and mercaptopurine can suppress normal bone marrow function and occasionally cause liver complications. Regular tests are vital as abnormalities in the blood may not produce symptoms straightaway. Recommendations suggest these tests should take place every week for some weeks after starting treatment, then fortnightly until your dose has been stable for six weeks, then monthly and eventually every three months. The frequency of blood tests may vary depending on the hospital that is treating you
Kidney function should be monitored
Treatment monitoring may be managed by your hospital team or shared between the hospital and your GP. You may be given a booklet to record your blood test results that you should take with you every time you see your GP, hospital doctor, specialist nurse or pharmacist, as it helps them to share information.