title: Serum thyroglobulin as a biomarker of iodine deficiency in adult populations.
abstract: To clarify which factors may influence the serum Tg level in an adult population and how this may affect Tg as a biomarker of iodine deficiency (ID).
  
  
  
  Two identical cross-sectional studies were performed before (C1a: 1997-98, n = 4649) and after (C2: 2004-05, n = 3570) the Danish mandatory iodine fortification (IF) of salt (2000). Additionally, a follow-up study of C1a was performed after IF (C1b: 2008-10, n = 2465). The studies took place in two regions with mild (Copenhagen) and moderate (Aalborg) ID before IF. Serum Tg was measured by immunoradiometric method and investigated as outcome variable in multivariate models.
  
  
  
  Multiple factors were associated with serum Tg. Some were directly related to iodine intake (cohort, urinary iodine concentration (UIC) level and region), and some were likely mediators of iodine intake effects on Tg (thyroid nodularity, thyroid size and autonomy with low TSH). Others were caused by Tg assay interference (Tg-Ab positivity), aggravation of ID (childbirths and smoking) or TSH stimulation of the thyroid. Estimated 24-h urinary iodine excretion was a more sensitive predictor of Tg than UIC. Iodine supplement users had low median Tg values compared with nonusers both before and after IF.
  
  
  
  Multiple factors should be taken into consideration when evaluating Tg as a marker of ID in adult populations, and the Tg results may depend on the assay used. Still, Tg is a sensitive marker of ID. We suggest including a reference population with known sufficient iodine intake when Tg is used to evaluate ID.
authors: Departments of Clinical Medicine and Endocrinology, Aalborg University and Aalborg University Hospital, Aalborg, Denmark.
authors: Anne
authors: A
authors: Krejbjerg
authors: Research Centre for Prevention and Health, The Capital Region of Denmark, Glostrup, Denmark.|Department of Endocrinology, Bispebjerg University Hospital, Copenhagen, Denmark.
authors: Lena
authors: L
authors: Bjergved
authors: Departments of Clinical Medicine and Endocrinology, Aalborg University and Aalborg University Hospital, Aalborg, Denmark.
authors: Inge
authors: I
authors: Bülow Pedersen
authors: Departments of Clinical Medicine and Endocrinology, Aalborg University and Aalborg University Hospital, Aalborg, Denmark.|Diagnostic Centre, Region Hospital Silkeborg, Silkeborg, Denmark.
authors: Allan
authors: A
authors: Carlé
authors: Department of Endocrinology, Bispebjerg University Hospital, Copenhagen, Denmark.
authors: Nils
authors: N
authors: Knudsen
authors: Department of Endocrinology, Bispebjerg University Hospital, Copenhagen, Denmark.
authors: Hans
authors: H
authors: Perrild
authors: Department of Gastroenterology, Slagelse Hospital, Slagelse, Denmark.
authors: Lars
authors: L
authors: Ovesen
authors: Department of Endocrinology, Bispebjerg University Hospital, Copenhagen, Denmark.
authors: Lone
authors: L
authors: Banke Rasmussen
authors: Departments of Clinical Medicine and Endocrinology, Aalborg University and Aalborg University Hospital, Aalborg, Denmark.
authors: Peter
authors: P
authors: Laurberg
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D003430:Cross-Sectional Studies; D019587:Dietary Supplements; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007455:Iodine / Q000008:administration & dosage / Q000172:deficiency* / Q000592:standards / Q000652:urine; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D013954:Thyroglobulin / Q000097:blood*; D013972:Thyrotropin / Q000097:blood; D055815:Young Adult
chemical_list: D015415:Biomarkers; D013972:Thyrotropin; D013954:Thyroglobulin; D007455:Iodine