What is a TPMT blood test used for?
The TPMT, RBC assay is used as a screen to detect individuals with low and intermediate TPMT activity who may be at risk for myelosuppression when exposed to standard doses of thiopurines, including azathioprine (Imuran) and 6-mercaptopurine (Purinethol).
What does TPMT stand for?
Thiopurine S-methyltransferase (TPMT) deficiency is a condition characterized by significantly reduced activity of an enzyme that helps the body process drugs called thiopurines.
What is the normal range for TPMT?
Reference Range: Normal TPMT activity: 25-65 U/mL – Individuals are predicted to be at low risk of bone marrow toxicity as a consequence of standard thiopurine therapy; no dose adjustment is recommended.
What is the normal function of the TPMT enzyme?
The TPMT gene provides instructions for making an enzyme called thiopurine S-methyltransferase (TPMT). This enzyme carries out a specific chemical reaction called S-methylation of a group of molecules known as aromatic and heterocyclic sulphydryl compounds.
Why is it important to check TPMT levels before commencing azathioprine?
Knowledge of the levels of TPMT enzyme activity would serve as a guide to clinicians prior to starting AZA and would also prevent potentially life threaten- ing bone marrow aplasia in patients with reduced enzyme activity.
What does a low TPMT mean?
Complete TPMT deficiency (TPMT <10 nmol/h/g Hb) indicates that there is an absolute intolerance to thiopurine drugs. Low activity indicates partial enzyme deficiency and therefore that the probability of azathioprine-induced bone marrow depression or nausea is HIGH.
What should be checked before starting azathioprine?
Taking azathioprine can sometimes affect your liver, kidneys or bone marrow. You will have blood tests to check your liver function, kidney function and blood count before you start taking this medicine. From week 1 to week 8 of your treatment you’ll have blood tests every week.
What does a high TPMT level mean?
Conversely, individuals with very high levels of TPMT activity are known to have the homozygous wild type phenotype, in which the clinical response to thiopurines is less likely. 3. This in turn suggests that pretreatment TPMT levels may be used to titrate the starting dose of azathioprine.
What does high TPMT mean?
Is azathioprine a high risk medication?
Azathioprine may increase your risk of developing certain types of cancer, especially skin cancer and lymphoma (cancer that begins in the cells that fight infection). If you have had a kidney transplant, there may be a higher risk that you will develop cancer even if you do not take azathioprine.
What should I avoid while taking azathioprine?
Wear protective clothing and hats, and stay out of direct sunlight between the hours of 10 am and 3 pm Avoid sunlamps and tanning beds. While you are being treated with azathioprine, and after you stop treatment with it, do not have any immunizations (vaccines) without your doctor’s approval.
Is azathioprine like chemo?
There are quite a few chemotherapy drugs on the market, but only three are widely used in treating rheumatic diseases today. They are Methotrexate (Rheumatrex), Azathioprine (Imuran), and Cyclophosphamide (Cytoxan). Methotrexate is the chemotherapeutic drug most widely used by rheumatologists.