Serum thyroglobulin as a biomarker of iodine deficiency in adult populations

TY - JOUR

T1 - Serum thyroglobulin as a biomarker of iodine deficiency in adult populations

AU - Krejbjerg, Anne

AU - Bjergved, Lena

AU - Bülow Pedersen, Inge

AU - Carlé, Allan

AU - Knudsen, Nils

AU - Perrild, Hans

AU - Ovesen, Lars

AU - Banke Rasmussen, Lone

AU - Laurberg, Peter

N1 - © 2016 John Wiley & Sons Ltd.

PY - 2016/9/1

Y1 - 2016/9/1

N2 - OBJECTIVE: 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).DESIGN AND METHODS: 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.RESULTS: 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.CONCLUSIONS: 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.

AB - OBJECTIVE: 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).DESIGN AND METHODS: 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.RESULTS: 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.CONCLUSIONS: 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.

KW - Journal Article

U2 - 10.1111/cen.13037

DO - 10.1111/cen.13037

M3 - Journal article

C2 - 26851767

SN - 0300-0664

VL - 85

SP - 475

EP - 482

JO - Clinical Endocrinology

JF - Clinical Endocrinology

IS - 3

ER -