Epic Code LAB1231951 Leflunomide Metabolite

Important Note

Patient should fast overnight prior to collection.

Test Name Alias

LAB1231257 | Quest: 18865 | LEFLUNOMIDE, Teriflunomide, Arava, Aubaigo

Interface Order Alias

1231951

Clinical Information

Leflunomide Metabolite - Leflunomide is an immunosuppressant medication used in the treatment of rheumatoid arthritis. Leflunomide is rapidly and extensively metabolized to teriflunomide, which is the active form of the medication. Steady state plasma concentrations in patients receiving recommended daily dosages: up to 63,000 ng/mL. It is recommended that all women of childbearing potential who discontinue leflunomide and women receiving treatment who wish to become pregnant undergo the cholestyramine drug elimination procedure. This procedure includes verification that plasma levels of teriflunomide are less than 20 ng/mL by two separate tests at least 14 days apart.

Specimen Requirements

Specimen Collection Criteria

Collect (preferred specimen): One plain Red-top tube.

Also acceptable: One Sodium heparin (green-top) or lithium heparin (green-top)

Not Acceptable: Serum separator tubes (SST) or Plasma separator tubes (PST)

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells. Transfer serum to plastic transport tube and maintain at room temperature (20-26°C or 68-78.8°F) prior to transport.

In-Lab Processing

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells. Transfer serum to plastic transport tube and maintain at room temperature (20-26°C or 68-78.8°F) prior to transport.

Specimen Transport Temperature

Transport: 1.0 mL serum or plasma, room temperature (20-26°C or 68-78.8°F)). (Minimum: 0.5 mL)

Rejection Criteria

Serum Separator (SST) tubes.
Specimens not collected and processed as indicated.

Specimen Stability

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 5 days
Refrigerated (2-8°C or 36-46°F): 14 days
Frozen (-20°C/-4°F or below): 30 days

Test Frequency

Performed: Tuesday, Thursday, Saturday..
Results available in 2-4 days.

Reference Range

Mean steady state plasma concentrations of teriflunomide from patients on daily dosages of 5, 10, or 25 mg of leflunomide were 8,800, 18,000 and 63,000 ng/mL, respectively. It is recommended that women of childbearing potential who discontinue leflunomide therapy undergo the cholestyramine drug elimination procedure. This procedure includes verification that plasma levels of teriflunomide are less than 20 ng/mL by two separate tests at least 14 days apart.

Performing Department

Send Outs

Performing Department Laboratory Location

Sent to Quest Diagnostics- Wood Dale, IL

Methodology

Chromatography/Mass Spectrometry

CPT

80193

LOINC

Teriflunomide 44828-2

Reviewed Date

11/1/2025

Orderable Regions