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Test ID FMERC Mercaptopurine (6-MP, Purinethol)

Method Name

High Performance Liquid Chromatography with Ultraviolet Detection (HPLC-UV)

Reporting Name

Mercaptopurine (6-MP, Purinethol)

Specimen Type


Specimen Required

Submit only 1 of the following specimens:



Draw blood in a green-top (sodium heparin) tube(s), plasma gel tube is not acceptable. Spin down and send 2 mL sodium heparin plasma refrigerated in a plastic vial.



Draw blood in a plain, red-top tube(s), serum gel tube is not acceptable. Spin down and send 2 mL of serum refrigerated in a plastic vial.

Specimen Minimum Volume

0.3 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Refrigerated (preferred) 7 days
  Frozen  180 days
  Ambient  72 hours

Reference Values

Units:          ng/mL


Mercaptopurine may be administered as an antineoplastic or may be present as a metabolite of the immunosuppressant drug azathioprine. Therapeutic and toxic ranges have not been established. Usual therapeutic doses of either mercaptopurine or azathioprine produce 6-mercaptopurine serum concentrations of less than 1000 ng/mL.


Day(s) and Time(s) Performed

Monday through Sunday

Performing Laboratory

Medtox Laboratories, Inc.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
FMERC Mercaptopurine (6-MP, Purinethol) 11242-5


Result ID Test Result Name Result LOINC Value
Z1190 6-Mercaptopurine 11242-5

NY State Approved