Changes in the prevalence of hypothyroidism: the HUNT Study in Norway

Abstract

Objective: Untreated hypothyroidism is common in iodine-replete areas. Frequent thyroid function testing and use of levothyroxine treatment for subclinical hypothyroidism suggest that the prevalence may have decreased. Therefore, in this study, we examined changes in the prevalence of hypothyroidism in a Norwegian county from 1995-1997 to 2006-2008 The corresponding decrease among men was 43% from 0.21 to 0.12% (PR 0.57; 95% CI 0.28-1.16). The prevalence of untreated subclinical hypothyroidism decreased by 64% from 3.0 to 1.1% in women (PR 0.36; 95% CI 0.31-0.42) and decreased by 54% from 2.1 to 1.0% in men (PR 0.46; 95% CI 0.38-0.56). Conversely, the prevalence of treated hypothyroidism among women increased by 60% from 5.0 to 8.0% (PR 1.60, 95% CI 1.50-1.71), and the corresponding prevalence in men doubled from 1.0 to 2.0% (PR 1.96; 95% CI 1.59-2.41). The prevalence of any form of hypothyroidism remained essentially similar at 9% in women and 3% in men. Conclusions: The prevalence of untreated hypothyroidism in this Norwegian county decreased strongly from 1995-1997 to 2006-2008. The findings suggest that the prevalence of untreated hypothyroidism in populations with easy access to thyroid function testing and levothyroxine treatment may now be low.

Prevalence of Undiagnosed Hypothyroidism in Europe: A Systematic Review and Meta-Analysis

“…The sample size of selected studies varied between 307 [34] and 80,490 [35]. The studies included sample populations from Austria [35], Belgium [36], Bulgaria [37], Denmark [38], Germany [39, 40], Italy [16, 18, 41], Norway [15, 42], Spain [17, 19, 34, 43], The Netherlands [44, 45], the UK [46, 47], and Turkey [48]. …”

“…The estimates can vary between 0.1 and 12.5%, depending on the definition used [15, 16]. For example, some studies evaluated the prevalence of undiagnosed and untreated subclinical and/or overt hypothyroidism [17-19], while others addressed previously diagnosed and treated hypothyroidism [20, 21].…”

The Hidden Phenomenon of Oxidative Stress During Treatment of Subclinical-Mild Hypothyroidism: A Protective Nutraceutical Intervention

“…Subclinical hypothyroidism (SH), defined as an elevated serum thyroid-stimulating hormone (TSH) level associated with serum thyroid hormone concentrations within the reference range, has been reported to affect 4-10% of Western populations. 2,3 Moreover, although depression of metabolism due to hypothyroidism has been described to decrease oxidant production and thus theoretically protect tissues against oxidative damage, clinical evidence points out that, on the contrary, patients with hypothyroidism have an increased risk of developing atherosclerosis. 4 SH is also considered either experimentally and clinically to be a definite risk factor for overall cardiovascular aging and disease.…”

Trends in the prevalence of autoimmune thyroiditis in the leading private health-care provider in Poland

“…It must be admitted that the prevalence of all forms of hypothyroidism did not change remarkably, as it was found in 9% of women and 3% of men. 24 The strength of the present study is a relatively high number of observations made in clinics from all over the country. Unlike other medical conditions (e.g.…”