Test Code

CPT Codes

Preferred Specimen
1 mL serum collected in a red top tube (no gel) or no additive (royal blue-top) tube or 1 mL plasma collected in a lithium heparin (green-top) tube

Patient Preparation
Draw at peak (2-4 hours after dose) or trough (0.5-1 hour before dose) at steady state

Minimum Volume
0.5 mL

Other Acceptable Specimens
Plasma collected in: Sodium heparin lead-free (tan-top) tube or sodium heparin (green-top) tube

Transport Temperature
Room temperature

Specimen Stability
Room temperature: 7 days
Refrigerated: 14 days
Frozen: 30 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Gel barrier/Serum separator tube (SST)

Chromatography/Mass Spectrometry

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

Setup Schedule
Set up: Mon-Sat; Report available: 2 days

Reference Range
Therapeutic Range
Dose (mg) Peak (mcg/mL) Trough (mcg/mL)
100 6.5-9.2 4.5-6.6
200 12.0-16.0 8.0-12.0
400 20.0-30.0 14.0-20.0

Clinical Significance
Topiramate is an anticonvulsant used as an adjunctive treatment of partial-onset epilepsy. Therapeutic drug monitoring is useful to optimize dose and avoid toxicity.

Performing Laboratory
Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly, VA 20153

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.