Finding the right psychiatric medication often takes more than one try. A patient starts a drug, waits weeks to see if it works, and then either tolerates it, stops it because of side effects, or moves to the next option. Pharmacogenomic (PGx) testing does not end that process, but it can remove some of the guesswork.
What a PGx test tells you
Many antidepressants and antipsychotics are broken down by liver enzymes, especially CYP2D6 and CYP2C19. Genetic variants change how active those enzymes are. A patient who metabolizes a drug slowly may build up high levels at a standard dose. A patient who metabolizes it very quickly may never reach an effective level.
A PGx test reports the patient’s variants and what they mean for specific drugs. Published dosing guidelines exist for a number of these gene-drug pairs.
What it does not tell you
A PGx result does not predict which medication will work. Response depends on diagnosis, history, other medications, and factors that no genetic test measures. Treat the report as one input to your decision.
When it is worth ordering
PGx testing is most useful when the result could change what you prescribe.
- The patient has failed two or more medications in the same class.
- The patient reports side effects at standard doses.
- The patient takes several medications that share a metabolic pathway.
- You are about to start a drug that has gene-based dosing guidance.
It is less useful for a patient who is stable and doing well on current therapy.
One test, used many times
Genes do not change, so a patient needs the test only once. The same result can inform prescribing decisions for years, including for drugs outside psychiatry such as opioids, antiplatelets, and statins.
How it works at TLS
- Panels: a psychiatric panel, a cardiovascular panel, and a comprehensive panel. Genes covered include CYP2D6, CYP2C19, CYP2C9, CYP3A4, CYP3A5, CYP1A2, CYP2B6, COMT, and OPRM1.
- Specimen: saliva or a cheek swab, collected in your office.
- Turnaround: 7 to 14 business days from receipt.
- Report: medications grouped by expected response, with the gene-drug evidence cited.
- Coverage: payer coverage varies, so we verify before testing.
More detail is on our PGx testing page. To add PGx testing to your practice, call (248) 800-6626 or open a provider account.
