Phenytoin, Free, Bound, and Total

Test Code

PTNFB

Quest Code

94572

CPT Codes
80185, 80186

Includes

Phenytoin, MEIA
Phenytoin, free, Immunoassay
Bound Phenytoin

Preferred Specimen

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

Patient Preparation
Collect as trough just prior to next dose. For patients receiving fosphenytoin therapy, collect as peak (at least 2 hours after IV infusion or at least 4 hours after IM injection).

Minimum Volume

2 mL

Transport Temperature

Room temperature

Specimen Stability

Room temperature: 4 days
Refrigerated: 7 days
Frozen: 30 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Serum separator tube (SST) • Plasma

Methodology
Immunoassay (IA) • Microparticle Enzyme Immunoassay (MEIA)

Setup Schedule

Set up: Mon-Fri; Report available: Next day

Reference Range

See Laboratory Report

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

Last Updated: July 17, 2024

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.