Test Overview
Test Methodology

Liquid Chromatography - Tandem Mass Spectrometry (LC-MS/MS)

Test Usage

Monitor therapeutic drug levels; monitor patient compliance; evaluate doxepin toxicity

Reference Range *

Therapeutic: 50 - 150 ng/mL (sum of Doxepin and Nordoxepin). Therapeutic ranges are for specimens drawn at trough (ie, immediately before next scheduled dose). Levels may be elevated in non-trough specimens.

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

Test Details
Days Set Up
Tuesday, Thursday, Sunday
Analytic Time

3 - 5 days

Soft Order Code
DXPIN
MiChart Code
Doxepin and Nordoxepin Level
Synonyms
  • Adapin
  • Sinequan
  • Tricyclics, Doxepin
  • DOXEPIN AND DEMETHYLDOXEPIN
  • DEDOX
  • DOX
  • Doxepin and Nordoxepin
  • DEMETHYLDOXEPIN
  • DOXEPIN
  • DOXEPIN RESULT
  • DOXEPIN & DEMETHYLDOXEPIN LEV
  • DOXEPIN + DEMETHYLDOXEPIN LEV
Laboratory
Sendout
Reference Laboratory
Mayo DXPIN
Section
Special Testing
Specimen Requirements
Collection Instructions

Collect blood in a red top tube immediately before next scheduled dose (minimum 12 hours after last dose); do not use SST tube. Centrifuge, aliquot serum or plasma into plastic vial within 2 hours of collection, and refrigerate.

Normal Volume
1 mL serum
Minimum Volume
0.25 mL serum
Rejection Criteria
SST or PST tube not acceptable.
Additional Information

Doxepin is a tricyclic antidepressant that has been reported to have less cardiotoxicity than the other TADs. Nordoxepine (Desmethyldoxepin), the metabolite of doxepin, is also measured. Test sent to Mayo Clinic Laboratories.

Billing
CPT Code
80335
Fee Code
AB142
LOINC
43122-1