Leflunomide Metabolite, Serum or Plasma
Also known as: LEFLUMETSP
Use
The test is used for therapeutic monitoring and evaluating the full elimination of Leflunomide, particularly in cases involving toxicity or pregnancy. Concentrations greater than 40.000 µg/mL tend to correlate with improved patient outcomes. For women treated with Leflunomide who wish to become pregnant, enhanced drug elimination is necessary until plasma teriflunomide concentrations are below 0.020 µg/mL on two tests taken at least 14 days apart.
Special Instructions
Specimen collection should be timed at predose (trough), 12 - 24 hours after the last dose. Separate the sample from cells within 2 hours of draw and transfer to an ARUP Standard Transport Tube.
Limitations
Therapeutic and toxic ranges are not well established. Adverse reactions such as diarrhea, hypertension, and liver toxicity do not correlate well with serum drug concentrations. The risk of teratogenesis must be considered for women who are treated with Leflunomide and wish to conceive.
New York Approved
Methodology
Mass Spectrometry
Biomarkers
LOINC Codes
- 44828-2
Result Turnaround Time
1-7 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.2 mL
Container
ARUP Standard Transport Tube
Collection Instructions
Separate from cells within 2 hours of draw.
Patient Preparation
Timing of specimen collection: Predose (trough). Obtain specimen 12 - 24 hours after last dose.
Causes for Rejection
Whole blood, potassium oxalate or separator tubes.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 7 days |
| Refrigerated | 17 days |
| Frozen | 90 days |