Thyroid hormone testing in the 21st century

Thyroid dysfunction and treatment follow up require accurate measurement of thyroid hormones. Most thyroid disease is treated on an outpatient basis; thus, assays have to be rapid and cost effective for optimal patient care. There are no rapid or point-of-care thyroid tests yet available, which could replace centralized automated thyroid testing. With the high population of thyroid dysfunction, it is important for thyroid assays to be available widely and locally. Immunoassays are most commonly used due to their ease and availability, but are limited in their accuracy. MS assays are much more specific, but are laborious with a high machine cost. Many hospitals may not be able to afford the machines and lack technical expertise. Sensitivity, specificity and standardization issues still result in substantial differences between various tests currently used for this population. To address these issues, new performance standards are being established by the professional organizations and technological advancements are being undertaken by instrument manufacturers. Automation solution is provided by various manufacturers and offers a choice for the hospital labs to select a platform which helps in their workflow and other chemistry testing. This has also resulted in decentralization and easy access to the thyroid testing. Even with these advancements, it is understandably confusing for clinicians to choose an assay for various clinical scenarios (20). As it becomes more available and standardized, LC-MS will continue to demonstrate its superiority to immunoassay.