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Test Code VENLA Venlafaxine, Serum

Reporting Name

Venlafaxine, S

Useful For

Monitoring serum concentration during therapy


Evaluating potential toxicity


The test may also be used to evaluate patient compliance.

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Serum Red

Specimen Required

Container/Tube: Red top

Specimen Volume: 1 mL

Collection Instructions:

1. Draw blood immediately before next scheduled dose. Serum drawn from patients 12 hours after an oral dose is appropriate. It is customary to treat the patient at bedtime with a dose, then, draw specimen the following morning prior to next dose.

2. Spin down within 2 hours of draw.

Specimen Minimum Volume

0.4 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Red Refrigerated (preferred) 14 days
  Ambient  14 days
  Frozen  14 days

Reference Values

Venlafaxine + O-desmethylvenlafaxine: 195-400 ng/mL

Day(s) and Time(s) Performed

Monday, Thursday; 4 p.m.

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
VENLA Venlafaxine, S 62849-5


Result ID Test Result Name Result LOINC Value
83732 Venlafaxine 9630-5
30195 O-desmethyl Venlafaxine 9630-5
32182 Venlafaxine+O-Desmethylvenlafaxine 62849-5

Clinical Information

Venlafaxine is a serotonin and norepinephrine reuptake inhibitor approved for treatment of major depression, anxiety and panic disorders, and social phobias. It is also used for bipolar disorder, bulimia, post-traumatic stress, obsessive behavior, and attention-deficit disorder. Venlafaxine is converted by CYP2D6 to the active metabolite, O-desmethylvenlafaxine. The therapeutic range for venlafaxine includes measurement if O-desmethylvenlafaxine; optimal response is seen when combined concentrations of parent and metabolite are between 195 and 400 ng/mL. Venlafaxine is significantly affected by reduced hepatic function, but only slightly by reduced renal function.


Average elimination half-lives are 5 hours for venlafaxine and 10 hours for O-desmethylvenlafaxine, which are much shorter than many other antidepressants. For this reason, extended release formulations are available. Time to peak serum concentration is 2 hours for the regular product and 8 hours for the extended release product. Common toxicities are mild, including drowsiness, dizziness, nausea, and headache.


Most individuals display optimal response to venlafaxine when combined serum levels of venlafaxine and O-desmethylvenlafaxine are between 195 and 400 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. Risk of toxicity is increased with combined levels >1,000 ng/mL. Therapeutic ranges are based on specimens drawn at trough (ie, immediately before the next dose).


Serum must be separated from cells within 2 hours of draw.


Specimens that are obtained from gel tubes are not acceptable.

Clinical Reference

1.  Wille SM, Cooreman SG, Neels HM, Lambert WE: Relevant issues in the monitoring and toxicology of antidepressants. Crit Rev Clin Lab Sci 2008;45(1):25-89

2. Baumann P, Hiemke G, Ulricj S, et al: The AGNP-TDM expert group consensus guidelines: therapeutic drug monitoring in psychiatry. Pharmacopsychiatry 2004;37:243-265

Method Description

Venlafaxine and venlafaxine metabolite are measured using acetonitrile precipitation and analysis by high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS).(Unpublished Mayo method)

Analytic Time

1 days

Specimen Retention Time

14 days

Reject Due To


Mild OK; Gross OK


Mild OK; Gross OK


Mild OK; Gross OK


Serum gel tube

NY State Approved


Method Name

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