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Test Code TPMT WB Thiopurine Methyltransferase, RBC

Clinical System Name

Thiopurine Methyltransferase

Sample Requirements

Specimen: Whole blood

Container(s): Dark Green/Sodium Heparin or Lavender/EDTA

Preferred Vol: 5.0 mL

Minimum Vol: 3.0 mL

Processing Instructions

Reject due to: Hemolysis; mild reject, gross reject

Spin: N

Aliquot: N

Temp: Refrigerated

Storage location: CPA 1, Sendouts Rack

 

Note: Also reject due to sodium fluoride/potassium oxalate (gray), gel separator tubes, frozen, or room temp

Stability

Specimen Type Temperature Time
  Room temp 3 h
  Refrigerated 6 d
  Frozen  

 

Availability

STAT Performed TAT
N M, W, F 3 - 4 d

 

Performing Laboratory

ARUP Laboratories

500 Chipeta Way
Salt Lake City, UT 84108-1221

 

Phone Number: (800) 522-2787

Department

Department: Send Outs

 

Phone Number: (206) 987-2563

Reference Range

Normal TPMT activity:

24.0-44.0 U/mL: Individuals are predicted to be at low risk of bone marrow toxicity (myelosuppression) as a consequence of standard thiopurine therapy; no dose adjustment is recommended.

 

Intermediate TPMT activity:

17.0-23.9 U/mL: Individuals are predicted to be at intermediate risk of bone marrow toxicity (myelosuppression) as a consequence of standard thiopurine therapy; a dose reduction and therapeutic drug management is recommended.

 

Low TPMT activity:

Less than 17.0 U.mL: Individuals are predicted to be at high risk of bone marrow toxicity (myelosuppression) as a consequence of standard thiopurine dosing. It is recommended to avoid the use of thiopurine drugs.

 

High TPMT activity:

Greater than 44.0 U/mL: Individuals are not predicted to be at risk for bone marrow toxicity (myelosuppression) as a consequence of standard thiopurine dosing, but may be at risk for therapeutic failure due to excessive inactivation of thiopurine drugs. Individuals may require higher than the normal standard dose. Therapeutic drug management is recommended.

Methodology

Method: Enzymatic/Quantitative Liquid Chromatography-Tandem Mass Spectomery

Analytical Volume: 3 mL

Limitations:

CPT Codes

82657

Send Out Instructions

Reference Test Name: Thiopurine Methyltransferase, RBC
Reference Test Number: 0092066
Instructions: Send out M - F with ARUP courier