Therapeutic monitoring and evaluating full elimination of the drug (eg, toxicity, pregnancy).
High Performance Liquid Chromatography/Mass Spectrometry
Sun, Wed, Fri
Timing of specimen collection: Predose (trough). Obtain specimen 12 - 24 hours after last dose.
Plain red. Also acceptable: Lavender (EDTA), pink (K2EDTA), green (sodium heparin), or gray (sodium fluoride).
Separate from cells within 2 hours of draw. Transfer 1 mL serum or plasma to an ARUP Standard Transport Tube. (Min: 0.2 mL)
Refrigerated. Also acceptable: Room temperature or frozen.
Whole blood. Potassium oxalate or separator tubes.
Ambient: 7 days; Refrigerated: 17 days; Frozen: 90 days
|Therapeutic Range||Greater than 40.000 µg/mL|
|Toxic Level||Not well established.|
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.
Laboratory Developed Test (LDT)
|Component Test Code*||Component Chart Name||LOINC|
|2007461||Leflunomide Metabolite, Serum/Plasma||44828-2|
- Arava® (Leflunomide (Teriflunomide), Serum or Plasma)
- leflunomide blood concentration