In:
The Journal of Clinical Endocrinology & Metabolism, The Endocrine Society, Vol. 92, No. 8 ( 2007-08-01), p. 3122-3127
Abstract:
Context: Iodine fortification (IF) of salt was introduced in Denmark in 1998. Little is known about the effect of a minor increase in iodine intake on the incidence of hypothyroidism. We prospectively identified all new cases of overt hypothyroidism in two areas of Denmark before and for the first 7 yr after IF had been introduced. Methods: A computer-based register was used to identify continuously all new cases of overt hypothyroidism in two subcohorts with previous moderate and mild iodine deficiency (ID), respectively (Aalborg, n = 310,124, urinary iodine = 45 μg/liter; and Copenhagen, n = 225,707, urinary iodine = 61 μg/liter). Data were obtained 1) before IF (1997–1998), 2) during voluntary IF (1999–2000), 3) during early (2001–2002) and 4) during late (2003–2005) period with mandatory IF. Results: The overall incidence rate of hypothyroidism increased during the study period: baseline, 38.3/100,000·yr; voluntary IF, 43.7 (not significant vs. baseline); early mandatory IF, 48.7 [vs. baseline, rate ratio (RR) = 1.27; 95% confidence interval (CI) = 1.10–1.47]; and late mandatory IF, 47.2 (vs. baseline, RR = 1.23; 95% CI = 1.07–1.42). There was a geographic difference because hypothyroidism increased only in the area with previous moderate ID: Aalborg, late mandatory IF vs. baseline, 40.3/29.7 (RR = 1.11; 95% CI = 1.11–1.66); Copenhagen, 56.7/51.6 (RR = 1.10; 95% CI = 0.90–1.34). The increase occurred in young and middle-aged adults. Conclusion: Even a cautious iodization of salt was accompanied by a moderate increase in the incidence rate of overt hypothyroidism. This occurred primarily in young and middle-aged subjects with previous moderate ID.
Type of Medium:
Online Resource
ISSN:
0021-972X
,
1945-7197
DOI:
10.1210/jc.2007-0732
Language:
English
Publisher:
The Endocrine Society
Publication Date:
2007
detail.hit.zdb_id:
2026217-6
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