Therapeutic drug monitoring (TDM) is a branch of clinical chemistry that specializes in the measurement of medication levels in serum. TDM requires that the laboratory make quantitative measurements of drugs and/or their metabolites. These measurements are made using patient serum samples. TDM should be contrasted with urine drug testing. While both measure drugs in patient specimens, urine drug testing is performed to detect drug abuse or confirm patient compliance when a patient is prescribed a drug with high abuse potential. Determining actual drug concentrations is less critical regarding urine drug screening. TDM, on the other hand, must provide accurate, quantitative serum concentrations for therapeutic drugs. Serum concentrations provided with TDM allow clinicians to adjust medication dosages and assess a patient's drug metabolism response and their compliance or dosing regimen.
