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 mL | Serum | No additive (Red) | Refrigerated | Do 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 mL | Plasma | EDTA (Lavender) | Refrigerated | Timing of specimen collection: Predose (trough). Obtain specimen 12 - 24 hours after last dose. Separate plasma from cells within 2 hours of collection. | |
| 1 mL | Plasma | Sodium heparin (Green) | Refrigerated | Timing of specimen collection: Predose (trough). Obtain specimen 12 - 24 hours after last dose. Separate plasma from cells within 2 hours of collection. | |
| 1 mL | Plasma | Potassium oxalate/sodium fluoride (Gray) | Refrigerated | Timing 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 |
|---|---|
| Refrigerated | 17 days |
| Frozen | 90 days |
| Ambient | 7 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.