Lab reference

TPMT Activity

Pre-Treatment

For education. Check every result.

Anatium is a study resource, not medical advice. Nothing here is a diagnosis, a prescription or a substitute for a clinician who has seen the patient. Check every number against a current local protocol before it touches anyone, and never act on a result you cannot reproduce yourself.

Reference range

RangeReported as enzyme activity

About

Activity of the enzyme that clears thiopurines, checked BEFORE azathioprine or mercaptopurine. Low activity means the standard dose causes profound marrow suppression. A normal TPMT does not exclude NUDT15 deficiency, which is common in East Asian and Hispanic patients.

When it is low

Low or absent activity: azathioprine and mercaptopurine cause profound myelosuppression. Recent blood transfusion can misclassify the phenotype

When it is high

Normal or high activity: standard dosing appropriate

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