title: Standardization of FT4 and harmonization of TSH measurements - a request for input from endocrinologists and other physicians.
abstract: Given the prevalence of thyroid disorders and the subtle signs and symptoms that may accompany subclinical disease, reliable laboratory testing for serum TSH and free thyroid hormones is important for both primary care physicians and endocrinologists. The laboratory community has recognized the need for standardization of thyroid function tests to achieve comparability of measurement results between methods. This applies in particular to tests for free T4 (FT4), which may be considered controversial in terms of clinical and analytical validity. However, variability is also observed with TSH testing - a fact which has not been emphasized in ongoing discussions regarding lowering the upper limit of normal and/or common decision limits to start treatment for hypothyroidism. In response to this need, the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) Committee for Standardization of Thyroid Function Tests worked over the years towards the goal of standardization of FT4 and TSH testing.
authors.affiliation: Mass Spectrometry Reference Laboratory LAC at Ghent University, Ghent, Belgium.
authors.forename: Linda M
authors.initials: LM
authors.lastname: Thienpont
authors.forename: James D
authors.initials: JD
authors.lastname: Faix
authors.forename: Graham
authors.initials: G
authors.lastname: Beastall
mesh_terms: D002624:Chemistry, Clinical / Q000379:methods / Q000639:trends; D004704:Endocrinology; D006801:Humans; D007390:International Agencies; D010820:Physicians; D017410:Practice Guidelines as Topic; D015203:Reproducibility of Results; D018570:Risk Assessment; D012958:Societies, Scientific; D013960:Thyroid Function Tests / Q000592:standards / Q000639:trends; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood*; D000078329:Workforce
chemical_list: D013972:Thyrotropin; D013974:Thyroxine