Tricyclic Antidepressant (TCA) Screen
Reviewed
Also called: TCA test, TCA screen, Tricyclic Screen
This test checks whether tricyclic antidepressants (TCA) can be found in your blood or urine. It can also measure how much TCA is in your blood or urine.
Specimen: Blood or urine
Urgent safety information
If you think you have taken too much of a TCA, or you have symptoms of a TCA overdose, call 911 or go to the nearest emergency center. Prompt treatment of an overdose can be lifesaving.
Emergency numbers on this page are for the United States. Outside the US, call your local emergency number.
Why this test may be ordered
- To help your provider prescribe the right dose of a TCA.
- To find out if you are misusing TCA (taking it without a prescription or taking more than the prescribed dose).
- To diagnose a TCA overdose.
- May be part of a drug (toxicology) screen.
Preparation and collection
You don't need any special preparations for a TCA screen.
A TCA screen can be done as a blood test or a urine test. During a TCA blood test, a health care professional will take a blood sample from a vein in your arm, using a small needle. For a TCA urine test, you will need to provide a sample of urine into a sterile cup. Your provider will give more information on how to collect your sample.
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly. There is no risk to having a urine test.
Understanding results
If a result or symptoms suggest an emergency, get emergency medical help right away.
Your blood test results will show the levels of TCA in your bloodstream. There are two types of urine test results.
- TCA level in blood: Your blood test results will show the levels of TCA in your bloodstream. Limitation: TCAs have to be carefully dosed. It can be hard to find a dose that is effective without being dangerous. Next step: Depending on which TCA you are taking and what the levels are, your provider may adjust your dosage.
- Dangerously high TCA level (blood or urine): If blood or urine test results show you have dangerously high levels of TCA, you will be treated immediately. Limitation: In fact, TCAs are the cause of many prescription drug overdose deaths in the United States. Next step: Prompt treatment of an overdose can be lifesaving.
- Urine screen: TCA found: One type will show whether TCA was found but not how much. Limitation: The other type shows the levels of TCA. Next step: If you have questions about your results, talk to your provider.
- Blood test: There is very little risk. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
- Urine test: There is no known risk.
- Results are interpreted by a healthcare professional; reference intervals depend on the specific TCA and clinical context.
What to do next
If you have questions about your results, talk to your provider.
- What is a tricyclic antidepressant (TCA) screen?
- Why do I need a TCA screen?
- What happens during a TCA screen?
- Will I need to do anything to prepare for the test?
- Are there any risks to the test? What do the results mean?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.
U.S. National Library of Medicine: Tricyclic Antidepressant (TCA) Screen