Leflunomide Metabolite

Leflunomide Metabolite

Test Code

18865
80193
18865
80193
Not offered in Quest Diagnostics Nichols Institute (IFD) – San Juan Capistrano. Please provide SERVICE AREA INFORMATION to find available tests you can order.
In-home collection may be available in your area for purchase through Quest Mobile.

Clinical Significance

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.

Test Details

Methodology

Chromatography/Mass Spectrometry

Assay Category

This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by FDA. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Reference Range(s)

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.

LOINC® Codes, Performing Laboratory

Methodology

Chromatography/Mass Spectrometry
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by FDA. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Reference Range(s)

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.

Preferred Specimen(s)

1 mL serum collected in a red-top tube (no gel)

Alternative Specimen(s)

Plasma collected in: Sodium heparin (green-top) or lithium heparin (green-top)

Minimum Volume

0.5 mL

Collection Instructions

Collect specimen in plain red-top tube. Avoid separator tubes.

Transport Container

Transport tube

Transport Temperature

Room temperature

Specimen Stability

  • Room temperature: 5 days
  • Refrigerated: 14 days
  • Frozen: 30 days

Reject Criteria

Serum separator tube (SST)

Setup Schedule

1 mL serum collected in a red-top tube (no gel)
Plasma collected in: Sodium heparin (green-top) or lithium heparin (green-top)
0.5 mL
Collect specimen in plain red-top tube. Avoid separator tubes.
Transport tube
Room temperature
Room temperature: 5 days
Refrigerated: 14 days
Frozen: 30 days
Serum separator tube (SST)
Not offered in Quest Diagnostics Nichols Institute (IFD) – San Juan Capistrano. Please provide SERVICE AREA INFORMATION to find available tests you can order.
In-home collection may be available in your area for purchase through Quest Mobile.
Test Details

Clinical Significance

Test Resources

Reference ranges are provided as general guidance only. To interpret test results use the reference range in the laboratory report.

The CPT codes provided are based on AMA guidance and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.

This material contains content from LOINC® (http://loinc.org). The LOINC Table, LOINC Table Core are copyright © 1995-2019, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee and is available at no cost under the license at http://loinc.org/license.

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