Evaluation of the Current State of Thyroid Hormone Testing in Human Serum—Results of the Free Thyroxine and Thyrotropin Interlaboratory Comparison
Ashley Ribera, Otoe Sugahara, Tatiana Buchannan, Norma Vazquez, Alicia N. Lyle, Li Zhang, Uliana I. Danilenko, and Hubert W. Vesper
Introduction Thyrotropin (TSH) and free thyroxine (fT4) are the two hormones initially measured in blood to assess hypoand hyperthyroidism and to guide treatment decisions.1–3 Some guidelines and recommendations suggest specific concentrations for these hormones to guide decision making.4 Therefore, accurate and reliable TSH and fT4 tests are needed to ensure correct patient care, making the standardization of thyroid function tests to assess both thyroid gland function and therapeutic drug monitoring a priority.5,6 Poor accuracy and comparability of TSH and fT4 tests have been described,7 and reference systems enabling consistent assay calibration and improving other analytical factors affecting inaccurate results have been established by the International Federation for Clinical Chemistry and Laboratory Medicine (IFCC) Committee on Standardization of Thyroid Function Tests in collaboration with the Centers for Disease Control and Prevention (CDC) Clinical Standardization Programs (CSP).7–9 Studies assessing the analytical performance of TSH and fT4 assays after these reference systems became available are very limited. As part of the CDC’s CSP for thyroid hormones, a study was conducted to obtain information about the current analytical performance of TSH and fT4 assays to assess potential improvements and to guide further standardization activities. READ ARTICLE…..
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