Days Set Up
Monday, Wednesday, Friday
Analytic Time

3 - 7 days

MiChart Code
Leflunomide Metabolite Serum (Sendout)
Soft Order Code

Test Updated:



Looking to order a test?

We’ve provided helpful links to make ordering easy.

Find a Requisition

All specimens should be accompanied by a requisition.

Submitting Specimens

Learn about how to properly label and where to ship specimens.

Order Kits and Supplies

MLabs provides all the supplies necessary for the collection of specimens.

Test FAQ

Visit our provider FAQ and learn about common questions to ordering tests.

Test Overview

Test Methodology

High Turbulence Liquid Chromatography–Tandem Mass Spectrometry (HTLC-MS/MS)

Test Usage

Therapeutic Drug Monitoring

Reference Range

Therapeutic: >40 mcg/mL; Elimination:

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Specimen Requirements

Collection Onsite

Collect specimen in a red top tube; SST acceptable. Deliver to Specimen Processing within 2 hours of collection.

Collection Offsite

Collect specimen in a red top (preferred) or SST tube. Centrifuge and aliquot serum into a plastic vial within 2 hours of collection. Store and transport at room temperature (preferred); specimen may be stored refrigerated or frozen for up to 14 days.

Red Top Tube
Normal Volume
1 mL serum
Minimum Volume
0.3 mL serum

Billing Information

CPT Code
Pro Fee Code

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Our High Standard

Quality that sets us apart

As the reference laboratory division of Michigan Medicine's Department of Pathology, MLabs shares the institution's commitment to applying established quality principles to clinical laboratory testing. Like other large organizations in complex, consequential fields, we rely on an established approach to monitor quality throughout the testing process.