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Interpretive Handbook

Test 9624 :
Trazodone, Serum

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Trazodone is indicated for treatment of depression characterized by a prominent and persistent dysphoric mood that interferes with daily function.


Trazodone is administered in oral doses of 150 to 400 mg/day in divided doses to yield blood levels of 650 to1,500 ng/mL that correlate with response to the drug.


Within the therapeutic range, trazodone is 93% protein bound. It exhibits a volume of distribution of 1.0 L/kg and an elimination half-life of 6 hours. Oral bioavailability ranges from 60% to 90%.


Priapism and hypotension are side effects that occur at therapeutic doses of the drug.


There are no known major drug interactions that affect the pharmacology of trazodone.


Toxicity is characterized by respiratory arrest, seizure, and electrocardiogram changes typical of atrioventricular conduction block. There is no specific antidote to trazodone overdose; treatment is symptomatic and supportive.

Useful For Suggests clinical disorders or settings where the test may be helpful

Monitoring for optimal therapeutic concentrations


Monitoring patient compliance

Interpretation Provides information to assist in interpretation of the test results

Most individuals display optimal response to trazodone when serum levels are 650 to 1,500 ng/mL. Some individuals may respond well outside of this range, or may display toxicity within the therapeutic range, thus, interpretation should include clinical evaluation. Toxic: >4,000 ng/mL. Therapeutic ranges are based on samples drawn at trough (ie, immediately before the next dose).

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

No significant cautionary statements

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Therapeutic concentration: 650-1,500 ng/mL

Clinical References Provides recommendations for further in-depth reading of a clinical nature

1. Burtis CA, Ashwood ER, Bruns DE, et al: Tietz Textbook of Clinical Chemistry and Molecular Diagnosis (Fifth edition), Elsevier, St. Louis, USA, 2012

2. DeVane CL: Pharmacokinetics of the newer antidepressants: Clinical relevance. Am J Med 1994;97:6-13