tricyclic antidepressants (TCA) in serum/plasma
Reference interval
- Not applicable.
Principle
The Serum TAD pack is used in the DuPont ACA discrete clinical analyzer to qualitatively screen for tricyclic antidepressants in serum & plasma. It is an adaptation of Syva's homogeneous enzyme immunoassay technique, EMIT. The reagents used in this methodology are matched lots of antitricyclic antidepressant antibody & the tricyclic antidepressant - glucose-6-phosphate dehydrogenase conjugate. The concentration of tricyclic antidepressants determines the amount of tricyclic antidepressant- glucose-6-phosphate dehydrogenase (TAD-G6PD) conjugate that is bound to the antitricyclic antidepressant antibody. The unbound conjugate catalyzes the oxidation of glucose-6-phosphate, with the simultaneous reduction of NAD to NADH, more rapidly than does the bound conjugate. The rate of increasing absorbance at 340 nm due to the increase in NADH is related to the level of tricyclic antidepressants by means of a calibration curve or a mathematical function.
Clinical significance
The urine serum tricyclic antidepressant assay is used to qualitatively detect tricyclic antidepressants in serum or plasma. This test provides only a preliminary analytical test result. A more specific alternate chemical method must be used in order to obtain a confirmed analytical result. Gas Chromatography/Mass Spectrometry (GC/MS) is the preferred confirmatory method. Clinical consideration & professional judgement should be applied to any drug of abuse test result, particularly when preliminary positive results are used.
False positive results may be produced by:
- chlorpromazine, cyclobenzaprine, carbamazepine, oxcarbazepine, cyproheptadine, diphenhydramine, quetiapine, ophenadrine
Specimen
Patient preparation: No special patient preparation is required.
Serum of plasma can be collected & stored by normal procedures. EDTA, oxalate, & fluoride anticoagulants do not interfere with the STAD method. Low recoveries have been reported with citrate and high variability, with some heparinized tubes.
More general terms
Additional terms
References
- ↑ ACA IV Discrete Clinical Analyzer Instrument Manual, Volume 1: Operation, DuPont Company, Wilmington, Delaware, 1984.
- ↑ ACA IV Discrete Clinical Analyzer Instrument Manual, Volume 3B: Chemistry, DuPont Company, Wilmington, Delaware, 1984.
- ↑ Trycyclic Antidepressant Ident, Quant Laboratory Test Directory ARUP: http://www.aruplab.com/guides/ug/tests/0090154.jsp
- ↑ Tricyclic Antidepressant Detection Laboratory Test Directory ARUP: http://www.aruplab.com/guides/ug/tests/0090307.jsp