Serum thyroglobulin before and after iodization of salt: an 11-year DanThyr follow-up study

Anne Krejbjerg; Lena Bjergved; Inge Bülow Pedersen; Allan Carlé; Nils Knudsen; Hans Perrild; Lars Ovesen; Lone Banke Rasmussen; Peter Laurberg

doi:10.1530/eje-15-0339

Serum thyroglobulin before and after iodization of salt: an 11-year DanThyr follow-up study

Anne Krejbjerg, Lena Bjergved, Inge Bülow Pedersen, Allan Carlé, Nils Knudsen, Hans Perrild, Lars Ovesen, Lone Banke Rasmussen, Peter Laurberg

Department of Clinical Medicine

4 Citations (Scopus)

Abstract

Objective: Our objective was to investigate individual serum thyroglobulin (Tg) changes in relation to iodine fortification (IF) and to clarify possible predictors of these changes. Design: We performed a longitudinal population-based study (DanThyr) in two regions with different iodine intake at baseline: Aalborg (moderate iodine deficiency (ID)) and Copenhagen (mild ID). Participants were examined at baseline (1997) before the mandatory IF of salt (2000) and again at follow-up (2008) after IF. Methods: We examined 2465 adults and a total of 1417 participants with no previous thyroid disease and without Tg-autoantibodies were included in the analyses. Serum Tg was measured by immunoradiometric method. We registered participants with a daily intake of iodine from supplements in addition to IF. Results: Overall, the follow-up period saw no change in median Tg in Copenhagen (9.1/9.1 mg/l, PZ0.67) while Tg decreased significantly in Aalborg (11.4/9.0 mg/l, P!0.001). Regional differences were evident before IF (Copenhagen/Aalborg, 9.1/11.4 mg/l, P!0.001), whereas no differences existed after IF (9.1/9.0 mg/l, PZ1.00). Living in Aalborg (P!0.001) and not using iodine supplements at baseline (PZ0.001) predicted a decrease in Tg whereas baseline thyroid enlargement (PZ0.02) and multinodularity (PZ0.01) were associated with an individual increase in Tg during follow-up. Conclusions: After IF we observed a decrease in median Tg in Aalborg and the previously observed regional differences between Aalborg and Copenhagen had levelled out. Likewise, living in Aalborg was a strong predictor of an individual decrease in serum Tg. Thus, even small differences in iodine intake at baseline were very important for the individual response to IF.

Original language	English
Journal	European Journal of Endocrinology
Volume	173
Issue number	5
Pages (from-to)	573-81
Number of pages	9
ISSN	0804-4643
DOIs	https://doi.org/10.1530/eje-15-0339
Publication status	Published - Nov 2015

Keywords

Adolescent
Adult
Aged
Denmark
Female
Follow-Up Studies
Food, Fortified
Humans
Iodine
Male
Middle Aged
Sodium Chloride, Dietary
Thyroglobulin
Young Adult

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title = "Serum thyroglobulin before and after iodization of salt: an 11-year DanThyr follow-up study",

abstract = "Objective: Our objective was to investigate individual serum thyroglobulin (Tg) changes in relation to iodine fortification (IF) and to clarify possible predictors of these changes. Design: We performed a longitudinal population-based study (DanThyr) in two regions with different iodine intake at baseline: Aalborg (moderate iodine deficiency (ID)) and Copenhagen (mild ID). Participants were examined at baseline (1997) before the mandatory IF of salt (2000) and again at follow-up (2008) after IF. Methods: We examined 2465 adults and a total of 1417 participants with no previous thyroid disease and without Tg-autoantibodies were included in the analyses. Serum Tg was measured by immunoradiometric method. We registered participants with a daily intake of iodine from supplements in addition to IF. Results: Overall, the follow-up period saw no change in median Tg in Copenhagen (9.1/9.1 mg/l, PZ0.67) while Tg decreased significantly in Aalborg (11.4/9.0 mg/l, P!0.001). Regional differences were evident before IF (Copenhagen/Aalborg, 9.1/11.4 mg/l, P!0.001), whereas no differences existed after IF (9.1/9.0 mg/l, PZ1.00). Living in Aalborg (P!0.001) and not using iodine supplements at baseline (PZ0.001) predicted a decrease in Tg whereas baseline thyroid enlargement (PZ0.02) and multinodularity (PZ0.01) were associated with an individual increase in Tg during follow-up. Conclusions: After IF we observed a decrease in median Tg in Aalborg and the previously observed regional differences between Aalborg and Copenhagen had levelled out. Likewise, living in Aalborg was a strong predictor of an individual decrease in serum Tg. Thus, even small differences in iodine intake at baseline were very important for the individual response to IF.",

keywords = "Adolescent, Adult, Aged, Denmark, Female, Follow-Up Studies, Food, Fortified, Humans, Iodine, Male, Middle Aged, Sodium Chloride, Dietary, Thyroglobulin, Young Adult",

author = "Anne Krejbjerg and Lena Bjergved and Pedersen, {Inge B{\"u}low} and Allan Carl{\'e} and Nils Knudsen and Hans Perrild and Lars Ovesen and Rasmussen, {Lone Banke} and Peter Laurberg",

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year = "2015",

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doi = "10.1530/eje-15-0339",

language = "English",

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TY - JOUR

T1 - Serum thyroglobulin before and after iodization of salt

T2 - an 11-year DanThyr follow-up study

AU - Krejbjerg, Anne

AU - Bjergved, Lena

AU - Pedersen, Inge Bülow

AU - Carlé, Allan

AU - Knudsen, Nils

AU - Perrild, Hans

AU - Ovesen, Lars

AU - Rasmussen, Lone Banke

AU - Laurberg, Peter

PY - 2015/11

Y1 - 2015/11

N2 - Objective: Our objective was to investigate individual serum thyroglobulin (Tg) changes in relation to iodine fortification (IF) and to clarify possible predictors of these changes. Design: We performed a longitudinal population-based study (DanThyr) in two regions with different iodine intake at baseline: Aalborg (moderate iodine deficiency (ID)) and Copenhagen (mild ID). Participants were examined at baseline (1997) before the mandatory IF of salt (2000) and again at follow-up (2008) after IF. Methods: We examined 2465 adults and a total of 1417 participants with no previous thyroid disease and without Tg-autoantibodies were included in the analyses. Serum Tg was measured by immunoradiometric method. We registered participants with a daily intake of iodine from supplements in addition to IF. Results: Overall, the follow-up period saw no change in median Tg in Copenhagen (9.1/9.1 mg/l, PZ0.67) while Tg decreased significantly in Aalborg (11.4/9.0 mg/l, P!0.001). Regional differences were evident before IF (Copenhagen/Aalborg, 9.1/11.4 mg/l, P!0.001), whereas no differences existed after IF (9.1/9.0 mg/l, PZ1.00). Living in Aalborg (P!0.001) and not using iodine supplements at baseline (PZ0.001) predicted a decrease in Tg whereas baseline thyroid enlargement (PZ0.02) and multinodularity (PZ0.01) were associated with an individual increase in Tg during follow-up. Conclusions: After IF we observed a decrease in median Tg in Aalborg and the previously observed regional differences between Aalborg and Copenhagen had levelled out. Likewise, living in Aalborg was a strong predictor of an individual decrease in serum Tg. Thus, even small differences in iodine intake at baseline were very important for the individual response to IF.

AB - Objective: Our objective was to investigate individual serum thyroglobulin (Tg) changes in relation to iodine fortification (IF) and to clarify possible predictors of these changes. Design: We performed a longitudinal population-based study (DanThyr) in two regions with different iodine intake at baseline: Aalborg (moderate iodine deficiency (ID)) and Copenhagen (mild ID). Participants were examined at baseline (1997) before the mandatory IF of salt (2000) and again at follow-up (2008) after IF. Methods: We examined 2465 adults and a total of 1417 participants with no previous thyroid disease and without Tg-autoantibodies were included in the analyses. Serum Tg was measured by immunoradiometric method. We registered participants with a daily intake of iodine from supplements in addition to IF. Results: Overall, the follow-up period saw no change in median Tg in Copenhagen (9.1/9.1 mg/l, PZ0.67) while Tg decreased significantly in Aalborg (11.4/9.0 mg/l, P!0.001). Regional differences were evident before IF (Copenhagen/Aalborg, 9.1/11.4 mg/l, P!0.001), whereas no differences existed after IF (9.1/9.0 mg/l, PZ1.00). Living in Aalborg (P!0.001) and not using iodine supplements at baseline (PZ0.001) predicted a decrease in Tg whereas baseline thyroid enlargement (PZ0.02) and multinodularity (PZ0.01) were associated with an individual increase in Tg during follow-up. Conclusions: After IF we observed a decrease in median Tg in Aalborg and the previously observed regional differences between Aalborg and Copenhagen had levelled out. Likewise, living in Aalborg was a strong predictor of an individual decrease in serum Tg. Thus, even small differences in iodine intake at baseline were very important for the individual response to IF.

KW - Adolescent

KW - Adult

KW - Aged

KW - Denmark

KW - Female

KW - Follow-Up Studies

KW - Food, Fortified

KW - Humans

KW - Iodine

KW - Male

KW - Middle Aged

KW - Sodium Chloride, Dietary

KW - Thyroglobulin

KW - Young Adult

U2 - 10.1530/eje-15-0339

DO - 10.1530/eje-15-0339

M3 - Journal article

C2 - 26245764

SN - 0804-4643

VL - 173

SP - 573

EP - 581

JO - European Journal of Endocrinology

JF - European Journal of Endocrinology

IS - 5

ER -

Serum thyroglobulin before and after iodization of salt: an 11-year DanThyr follow-up study

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Keywords

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