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Thiopurine metabolites (6-TGN)

Medicine levels · also printed as 6-TGN, 6-thioguanine nucleotides, Thiopurine metabolites, 6TGN, 6-TG nucleotides

Typical UK adult range235 to 450 pmol/8x10^8 RBC

Target ranges are set by the treating team and printed by the lab; the printed range applies.

What this test measures

6-TGN is the active breakdown product of azathioprine and mercaptopurine, measured inside red cells. Together with 6-MMP it shows whether the medicine is being taken and handled in the usual way.

Why doctors request it

Measured by bowel and skin specialists when the medicine seems not to be working or side effects occur.

What commonly pushes it up

Some medicines as a class, for example allopurinol, which shift the metabolism

What commonly pushes it down

Missed tablets
A metabolism that favours the other product (6-MMP)

Everyday reasons for a value outside the range

Ranges come from bowel disease studies and are applied loosely elsewhere

About the sample

No special timing.

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

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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.