Test guide
Therapeutic Drug Monitoring
Therapeutic drug monitoring (TDM) is testing that measures the amount of certain medicines in your blood. It checks whether the amount of medicine you take is safe and effective.
What it is for
Therapeutic drug monitoring (TDM) helps determine the best dosages if you're taking certain hard-to-dose medicines. Many medicines that require TDM are ones that you might take for a long time. While you are taking the medicines, you may have changes that could affect the medicine levels in your blood. These may include: For each of these changes, you may need to change your medicine dose. Otherwise, you might have too little medicine, which might not be effective, or too much (toxicity), which might not be safe. Source: MedlinePlus, National Library of Medicine. Medical test information is public domain. Source identity and definition checked automatically on 2026-10-18. No individual clinical interpretation or human reviewer is asserted.
Limitations
Reference intervals and interpretation depend on the laboratory, specimen, method and clinical context. This source definition is educational information; it does not establish a diagnosis, product approval or suitability for an individual.
Also known as
- medicine levels blood test, therapeutic drug levels
Reviewed products
Curated product links for this test are still under editorial review. Meanwhile, browse the product directory or request a supplier match below.