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UW Health SMPH
American Family Children's Hospital

UW Hospital and Clinics Lab Test Directory

Test Name: Amitriptyline / Nortriptyline

Test Code(s): AMTP / XAMIT

CPT Code(s): 80335

Test Description: Test Component:

Amitriptyline and its major active metabolite, nortriptyline.

Methodology: Liquid Chromatography

Clinical Significance: Antidepressant

Days Performed: Daily, dayshift.

Turnaround Time: Routine: 24 hours.

Specimen Requirements

Specimen: Blood

Patient Preparation: Patient should be on the same dose for at least five days before collecting drug level.

Collection Instructions: Collect specimen for trough level prior to next dose.

Collection Container: Preferred: Red top

Collection Volume: Preferred: 4 mL
Pediatrics: 4 mL

Sample Analyzed: Serum

Volume Required: Preferred: 2 mL
Pediatrics: 1.5 mL

Specimen Processing: Centrifuge. Transfer cell-free serum to plastic vial. Refrigerate.

Specimen Transport: Transport specimen to UWHC Core Laboratory (B4/220). Transport with coolant pack if coming from outreach location.

Unacceptable Criteria: Specimens collected in red cap with yellow ring (SST) tubes are not acceptable.

Stability: Ambient: 5 days
Refrigerated: 7 days
Frozen: 1 year


Interpretive Guidelines:
Generally effective therapeutic concentration: 
18 years and up:

Amitriptyline plus

nortriptyline: 120 - 250 ng/mL

18 years and up:

Total tricyclic antidepressant

concentration in excess of 500 ng/mL

Critical Calls: View

Additional Information:

Result of "BELOW" indicates that the result is below method detection limit of 10 ng/mL. The half-life of amitriptyline is 8-47 hours and the half-life of nortriptyline is 9-63 hours. Amitriptyline may enhance the effects of alcohol, barbiturates, and other CNS depressants.


This test was developed and its performance characteristics determined by the UWHC Clinical Laboratories.  This test meets the standards for clinical testing.  This test should not be regarded as investigational or for research use.  The US Food and Drug Administration (FDA) has not approved or cleared this test; however, the FDA has determined that such clearance or approval is not necessary.


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