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Thiopurine Methyltransferase (TPMT) Activity Profile, Erthrocytes

Test Code:



Specimen Container

EDTA tube

Specimen Requirement

Whole Blood EDTA
3 mL

Between 8 am to 9 am on Monday only, collect 3 mL of fresh blood from patient and despatch immediately to DPLM Client Service. Specimen is not to be collected on Tuesday to Sunday, eve of public holidays and public holidays.

Specimen Storage / Transport

Keep specimen at room temperature. DO NOT send on ice or refrigerant. Despatch to KKH DPLM Client Services as soon as possible as blood must reach NUH by 12 noon.



Orderable as STAT?


Turn Around Time

Reference Value(s)

Testing Laboratory Location



Mayo Medical Laboratories in Rochester

Contact Number

6394 1352

Day and Time Performed

Monday only except for Public Holidays and eves of Public Holiday, between 8 to 9 am.

Orderable on CPOE?


Additional Information

Patient preparation:

Patients should abstain from the following drugs for at least 48 hours prior to TPMT testing: naproxen (Aleve), ibuprofen (Advil, Motrin), ketoprofen (Orudis), furosemide (Lasix), sulfasalazine (Azulfidine), mesalamine (Asacol), olsalazine (Dipentum), mefenamic acid (Ponstel), trimethoprim (Proloprim), methotrexate, thiazide diuretics, and benzoic acid inhibitors.

This test is useful for the detection of individuals with low thiopurine methyltransferase (TPMT) activity who are at risk for excessive myelosuppression or severe hematopoietic toxicity when taking thiopurine drugs.

Detection of individuals with hyperactive TPMT activity who have therapeutic resistance to thiopurine drugs and may develop hepatotoxicity if treated with these drugs.

Change History Notes



Thiopurine Methyltransferase (TPMT) Activity Profile, Erthrocytes RV0052

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