Can thyroid hormone mimics affect thyroid hormone measurement by immunoassay?

This study aims to determine whether the environmental pollutant and thyroid mimic, tetrabromobisphenol A (TBBPA), interferes with thyroid hormone measurement by immunoassays. Hormone-relevant concentrations of TBBPA were added to thyroid hormone-stripped human serum and subjected to 6 different thyroid hormone immunoassays. TBBPA was negative in all of the thyroid hormone immunoassays tested except at very high concentration (above that expected in serum of TBBPA-exposed workers) where it gave a marginally positive result in one immunoassay (in house T4 radioimmunoassay (RIA)). Serum TBBPA present as a result of workplace exposure or its use as a fabric flame retardant is very unlikely to give false positive results in thyroid hormone immunoassays. •Thyroid hormone mimics have structural analogies to thyroid hormones.•They might interfere with thyroid hormone immunoassays.•Tetrabromobisphenol A (TBBPA) is a potent thyroid hormone mimic flame retardant.•TBBPA is present in blood of exposed people.•TBBPA does not affect thyroid hormone immunoassays at clinically relevant levels.