Days Set Up
Analytic Time

7 - 12 days

Soft Order Code

Test Updated:


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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 Performance Liquid Chromatography with Fluorescence Detection

Test Usage
Reference Range

The expected serum concentration in patients on usual daily dosages is up to 5 mcg/mL. Toxic: >50 mcg/mL.

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

Specimen Requirements

Collection Offsite

Collect trough specimen in a green top or red top tube. Centrifuge, aliquot plasma or serum into a plastic vial and refrigerate.

Normal Volume
1 mL plasma or serum
Minimum Volume
0.25 mL plasma or 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.