Leflunomide Metabolite




Test Mnemonic

LEFLUN

CPT Codes

  • 80193 - QTY (1)

Aliases

  • A77 1726
  • Arava
  • Teriflunomide

Includes

  • Teriflunomide

Performing Laboratory

ARUP


Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
1 mLSerumNo additive (Red) RefrigeratedDo not use serum separator tube. Timing of specimen collection: Predose (trough). Obtain specimen 12 - 24 hours after last dose. Separate serum from cells within 2 hours of collection.

Alternate Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
1 mLPlasmaEDTA (Lavender) RefrigeratedTiming of specimen collection: Predose (trough). Obtain specimen 12 - 24 hours after last dose. Separate plasma from cells within 2 hours of collection.
1 mLPlasmaSodium heparin (Green) RefrigeratedTiming of specimen collection: Predose (trough). Obtain specimen 12 - 24 hours after last dose. Separate plasma from cells within 2 hours of collection.
1 mLPlasmaPotassium oxalate/sodium fluoride (Gray) RefrigeratedTiming of specimen collection: Predose (trough). Obtain specimen 12 - 24 hours after last dose. Separate plasma from cells within 2 hours of collection.

Minimum Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
0.2 mL     

Stability

Environmental Condition Description
Refrigerated17 days
Frozen90 days
Ambient7 days

Days Performed

Sun, Wed, Fri

Turnaround Time

2 - 8 days

Methodology

Name Description
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) 

Reference Range

Leflunomide Metabolite
Sex Age From Age To Type Range Range Unit
       Therapeutic Range: Greater than 40.000 ug/mL 
       Toxic Level: Not well established 

Special Info

Timing of specimen collection: Predose (trough). Obtain specimen 12 - 24 hours after last dose. This test is New York DOH approved.

Clinical Info

Therapeutic monitoring and evaluating full elimination of the drug (eg, toxicity, pregnancy). 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.