Leflunomide Metabolite, Serum or Plasma
2007460
Ordering Recommendation
Intended for therapeutic drug monitoring and evaluating full elimination of the drug (eg, toxicity, pregnancy).
Mnemonic
LEFLUMETSP
Methodology
High Performance Liquid Chromatography/Mass Spectrometry
Performed
Wed, Sun
Reported
1-6 days  
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
Specimen Required
Patient Preparation
Timing of specimen collection: Predose (trough). Obtain specimen 12 - 24 hours after last dose.  
Collect
Plain red. Also acceptable: Lavender (EDTA), pink (K2EDTA), green (sodium heparin), or gray (sodium fluoride).  
Specimen Preparation
Separate from cells within 2 hours of draw. Transfer 1 mL serum or plasma to an ARUP Standard Transport Tube. (Min: 0.2 mL)  
Storage/Transport Temperature
Refrigerated. Also acceptable: Room temperature or frozen.  
Unacceptable Conditions
Whole blood. Potassium oxalate or separator tubes.   
Remarks
  
Stability
Ambient: 7 days; Refrigerated: 17 days; Frozen: 90 days  
Reference Interval
 
 
Therapeutic Range Greater than 40.000 µg/mL
Toxic Level Not well established.
Interpretive Data
Therapeutic and toxic ranges are not well established. Concentrations greater than 40.000 µg/mL tend to correlate with improved patient outcome. A proposed therapeutic range is 50.000-100.000 µg/mL. Adverse reactions to Leflunomide, such as diarrhea, hypertension, and liver toxicity, do not correlate well with serum drug concentrations. Leflunomide has a potential risk for teratogenesis. For women being treated with Leflunomide who desire to become pregnant, enhanced drug elimination should be performed until plasma teriflunomide concentrations are lower than 0.020 µg/mL on two separate tests taken at least 14 days apart.

See Compliance Statement B: www.aruplab.com/CS  
Note
 
CPT Code(s)
80299
Components
Component Test Code*Component Chart Name
2007461Leflunomide Metabolite, Serum/Plasma
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Aliases
  • Arava
  • Arava® (Leflunomide (Teriflunomide), Serum or Plasma)
  • leflunomide blood concentration
  • Teriflunomide