The Case for Laboratory Developed Procedures: Quality and Positive Impact on Patient Care

Kaul, Karen L.; Sabatini, Linda M.; Tsongalis, Gregory J.; Caliendo, Angela M.; Olsen, Randall J.; Ashwood, Edward R.; Bale, Sherri; Benirschke, Robert; Carlow, Dean; Funke, Birgit H.; Grody, Wayne W.; Hayden, Randall T.; Hegde, Madhuri; Lyon, Elaine; Murata, Kazunori; Pessin, Melissa; Press, Richard D.; Thomson, Richard B.

Older competitive Tg-RIA methods are available but produce falsely high Tg results in the presence of Tg autoantibodies (Tg-Ab). 166 Newer FDA-cleared Tg assays are immunometric immunoassays (Tg-IA) and can detect Tg at concentrations down to approximately 0.1 ng/mL. Generally, Tg is captured with a solid-phase antibody, then quantitated using a detection anti-Tg reagent. The signal is directly proportional to the amount of Tg. The assay design is susceptible to interference from endogenous anti-Tg-Ab. 166 The intended use of these Tg-IA are Tg measurement in Tg-Ab-negative (Tg-Ab À ) patients. The FDA requires Tg-Ab testing whenever Tg is measured using these cleared methods.