Amitriptyline and Nortriptyline, Serum
Use
This test is useful for monitoring the serum concentrations of amitriptyline and nortriptyline during therapy. It aids in evaluating potential toxicity and patient compliance with the drug regimen. Amitriptyline is a tricyclic antidepressant that is metabolized to nortriptyline, both of which are used in treating depression, depending on the desired side effects. Monitoring is critical to ensure blood levels remain within the therapeutic window to avoid toxicity, characterized by cardiac issues at levels above 500 ng/mL.
Special Instructions
Specimens must be collected immediately before the next scheduled dose, ideally 12 hours after the last dose. Serum should be separated from cells within two hours of collection to prevent inaccurately elevated drug levels.
Limitations
This test should not be performed on whole blood. Using serum gel/SST tubes can cause drug absorption on the gel, leading to falsely decreased concentrations. Improper separation of serum from cells can result in falsely elevated tricyclic antidepressant levels. Reference ranges are based on specimens collected at trough levels, and variations in these conditions may affect the results.
New York Approved
Methodology
Mass Spectrometry (LC-MS/MS)
Biomarkers
LOINC Codes
- 43106-4
- 3333-2
- 3872-9
- 3335-7
Result Turnaround Time
2-5 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.25 mL
Container
Plastic vial
Collection Instructions
Collect specimen immediately before next scheduled dose (minimum 12 hours after last dose). Centrifuge and aliquot serum into a plastic vial. Serum must be separated from cells within 2 hours of collection.
Causes for Rejection
Gross hemolysis, Gross lipemia, Gross icterus
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 7 days |
| Refrigerated | 28 days |
| Frozen | 28 days |