Thioguanine nucleotides (TGN) (thiopurine metabolites)
Analysis of the active thiopurine metabolites (6TGN & 6MMPN) of the thioguanine drugs azathioprine, 6-mercaptopurine and 6-thioguanine. This test may be requested to determine the correct treatment regimes in patients who have TPMT heterozygous status who exhibit a low TPMT enzyme activity where reduced dose regimes are being used or where it is unclear that therapeutic levels are being achieved. Please provide details of current thiopurine drug regime and patient diagnosis on the request form.
| Tube | 03 (EB) - EDTA Blood |
|---|---|
| ID | Tests&Tubes0244 |
| Additional Information | Only routinely available for Paediatric Oncology and Gastroenterology, otherwise please discuss request with the Duty Biochemist (0113 39 26922 option 2) |
| Turn Around | Turnaround time stated by City Hospital, Birmingham: 2 working days |
| Send to | Blood Sciences LGI (Test referred to: City Hospital) Birmingham. |
| Contact | For further details please contact Leeds Pathology customer services: leedsth-tr.pathologycustomerservice@nhs.net. |
| Collection Con | Minimum Volume: 0.5 mL Instructions to lab: DO NOT CENTRIFUGE. Store whole blood in fridge. DO NOT FREEZE. |
| Sample REQ | Blood |
| Ref. Range Notes | 6-TGN 235 - 450 pmol/8x108 RBCs (maximum drug efficacy). 6-MMPN < 5700 pmol/8x108 RBCs. If > 5700, increased risk of hepatotoxicity. |
| Telepath | LGI superset LTGN. SJUH superset JTGN. |
