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TPMT genotype

Genetic tests · also printed as TPMT genotype, TPMT gene, TPMT variant, TPMT*3A, TPMT*3C

Typical UK adult rangeExpected result: Not detected

Wild type (normal) is the usual result.

What this test measures

The TPMT genotype identifies inherited variants in the enzyme that breaks down azathioprine and mercaptopurine, as an alternative to measuring the enzyme activity directly.

Why doctors request it

Tested once before starting azathioprine or mercaptopurine, as an alternative to the enzyme activity test.

What commonly pushes it up

What commonly pushes it down

Everyday reasons for a value outside the range

About the sample

No fasting needed.

Written by a UK consultant physician. Typical UK adult reference ranges; your laboratory's own printed range takes precedence.

Got a report with TPMT genotype on it?

Upload a photo or PDF and see every line against the range your lab printed, explained in plain English. First report free.

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This is an educational summary of results you uploaded. It is not medical advice, a diagnosis or a treatment plan, and it does not replace the doctor who requested the test. If you are worried, or a result is marked outside range, discuss it with your doctor. Written and reviewed by a UK consultant physician. Reference ranges vary between laboratories.