Tricyclic Antidepressant Screen
Does this test have other names?
Tricyclic antidepressant (TCA) testing
What is this test?
This test is used to check a sample of blood or urine for tricyclic antidepressants
(TCAs). Healthcare providers prescribe these medicines for depression and a number
of other problems. These include anxiety, headaches, and nerve-related pain.
These medicines can be helpful in normal doses. But taking too much can be fatal.
These medicines are often the cause of death in prescription-medicine overdoses in
Why do I need this test?
You may need this test to help your healthcare provider prescribe the proper dose
of a TCA. Healthcare providers may also do this test if you have symptoms that may
point to taking too much of one of these medicines.
Symptoms of overdose include:
What other tests might I have along with this test?
If your healthcare provider suspects that you have taken too much of one of these
medicines, he or she may do an electrocardiogram to check your heart's rhythm. Your
provider may also order other blood tests. These include a complete blood count, creatinine,
electrolytes, and blood sugar. He or she will also check for other substances that
are commonly taken along with a TCA overdose.
What do my test results mean?
A result for a lab test may be affected by many things, including the method the laboratory
uses to do the test. If your test results are different from the normal value, you
may not have a problem. To learn what the results mean for you, talk with your healthcare
Depending on the tricyclic antidepressant medicine you are taking, the level for treatment
will range from 50 to 250 nanograms per milliliter (ng/mL). Toxic levels are above
300 to 500 ng/mL.
How is this test done?
The test is done with a blood sample. A needle is used to draw blood from a vein in
your arm or hand. Or it is done with a urine sample, which is usually provided by
urinating into a cup. The result of a urine test for TCAs will be reported only as
negative or positive.
Does this test pose any risks?
Having a blood test with a needle carries some risks. These include bleeding, infection,
bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may
feel a slight sting or pain. Afterward, the site may be sore.
What might affect my test results?
Some other medicines can interfere with this test, causing a false-positive for TCAs.
These include carbamazepine, quetiapine, diphenhydramine, thioridazine, chlorpromazine,
How do I get ready for this test?
Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements
you are taking. This includes medicines that don't need a prescription and any illicit
drugs you may use.