The Abbott TDx immunoassay chemistry analyzer uses a technology known as FPIA (Fluorescence Polarization Immunoassay) to measure serum drug concentration in a patient. Due to its high level of design and engineering the TDx offers; ease of use, quality of results, reliability. The following assays can all be performed on this automated instrument; therapeutic drugs, hormones, clinical chemistries, specific proteins and toxic/abused drugs. Tests on the TDx include; abused drugs, thyroid, fertility, therapeutic drug monitoring, thyroid and transplant.