Days Set Up
Daily, 24 hrs.
Analytic Time

2 hours

MiChart Code
Phenytoin Level, Free
Soft Order Code

Test Updated:


Dilantin, Protein Free
Free Dilantin
Free Phenytoin

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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

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Test Overview

Test Methodology

Kinetic Immunoassay (KIMS).

Test Usage

Evaluate phenytoin toxicity

Reference Range

1-2 mcg/mL (Approximately 10% of the total drug concentration). Toxic levels: greater than 3 mcg/mL.

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

Specimen Requirements

Offsite Collection Instructions

Collect blood in a red top tube; do not use SST tube. Centrifuge, aliquot serum into a plastic vial, and refrigerate.

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

Billing Information

CPT Code
Pro Fee Code
Insurance Auth Info

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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.