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NORTRIPYLINE, serum (8000100858)
Test Mnemonic:


Specimen Requirements:


Routine venipuncture. The optimal time for collection of specimens for steady-date levels is between 10 and 14 hours after the last dose of medication for patients taking antidepressants once a day, and just before the morning dose for patients who are on a divided dose schedule.  Collect 7 mL of blood in Red-topped tube. Do not use SST/serum separator tubes. (Min.: 3mL of blood).

DO NOT draw blood in SST/gel separator vacutainer tube.


 Red-topped tube

Minimum Volume:

3mL of blood


Delivered to Sample Management within 2 hours of collection.

Specimen Preparation:

Allow specimen to clot completely at room temperature. Centrifuge to separate serum from cells within 2 hours of collection. Transfer serum from collection tube to labeled plastic transport tube. 



Store frozen (if analysis is not performed immediately) for ≤1 year. (Avoid repeated freeze/thaw cycles).   

Causes for Rejection:

Blood drawn in SST/gel separator vacutainer tube, incomplete and/or incorrect sample identification, improper storage/transport, gross hemolysis, icterus or lipemia.                             

Reference Range:

By report (reports may vary based on instrumentation, patient age and sex)

Turnaround Time:

Routine: 3-5 days




Special  Chemistry: Monday – Friday:  7 am – 3:30 pm.

CPT 4 Code:



Blood samples received in the TDM laboratory before noon on the day of analysis will be included on the run. STAT requests after 4:00 PM require the approval of the director or pathology resident on call. Metabolites of cyclobenzaprine (Flexeril) may cause interference. Nortriptyline cannot be quantitated if the patient is also on cyclobenzaprine. Some of the phenothiazines may also interfere.

When ordering tests for which Medicare or Medicaid reimbursement will be sought, physicians should only order tests that are medically necessary for the diagnosis or treatment of the patient. Components of the organ or disease panels may be ordered individually. The diagnostic information must substantiate all tests ordered and must be in the form of an ICD-10 code or its verbal equivalent.
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