Reciprocal Changes of Serum Thyroglobulin and TSH in Residents of a Moderate Endemic Goitre Area

Abstract

Subjects living in iodine deficient areas were reported to have elevated serum thyroglobulin (Tg) concentrations. This finding was interpreted as related to thyroid stimulation. Discrepant results, however, were found when serum Tg concentrations were correlated either with serum TSH or with goitre size. In this study we investigated the relationships between goitre size, serum Tg and serum TSH in 488 unselected adult subjects living in an endemic area of North-Western Tuscany (Garfagnana district). The control group comprised 352 subjects residing in a non-endemic area. In the endemic area a high prevalence of goitre was found (80.1%), thyroid enlargement being slight to moderate in the majority of cases and very large only in six subjects. Serum Tg concentrations increased and serum TSH levels decreased with the size of goitre. Statistical analysis by the chi-square cross correlation test showed that the converse changes of serum Tg and serum TSH in relation to goitre size were highly significant. These findings indicate that the increase of serum Tg occurring in endemic goitrous subjects may be related to factors other than TSH stimulation. Functional autonomy of the thyroid may account for the finding of low serum TSH and elevated serum Tg values in patients with large goitres. The present data do not exclude the possibility that the release of Tg is influenced by TSH stimulation, but indicate that other factors may be responsible for the increased levels of Tg found in endemic goitre.

Lower levels of TSH are associated with a lower risk of papillary thyroid cancer in patients with thyroid nodular disease: thyroid autonomy may play a protective role

“…This finding has already been observed in iodine deficient areas, such as those the majority of our patients came from, where longstanding iodine deficiency causes higher frequency of thyroid nodularity and autonomy in older people (Fenzi et al 1985, Vitti et al 1990, Aghini-Lombardi et al 1999. When patients were classified as affected by benign thyroid disease or PTC according to the results of cytology, the age-dependent reduction of TSH levels was highly significant in the first group, while in patients with PTC this phenomenon was much less evident.…”

Factors associated with serum thyroglobulin in a Ukrainian cohort exposed to iodine-131 from the accident at the Chernobyl Nuclear Plant

“…Previous studies have reported elevated serum Tg in females (Cahoon et al, 2013;Fenzi et al, 1985;Giovanella et al, 2011;Knudsen et al, 2001;Thomson et al, 2001;Vejbjerg et al, 2009) and with attained age (Cahoon et al, 2013;Knudsen et al, 2001;Vejbjerg et al, 2009), while Giovanelli et al (2011 reported no difference in serum Tg by age in healthy individuals-suggesting that differences in serum Tg by age are due to thyroid dysfunction. We found higher serum Tg levels in females than males, and among older individuals in this study, which may be attributed to higher prevalence of thyroid diseases in these groups (despite adjusting for known thyroid abnormalities and dysfunction).…”

Thyroglobulin as a Biomarker of Iodine Deficiency: A Review

“…Of these, nine were randomized controlled trials, two were nonrandomized controlled trials, three were cohort observational studies, 23 were cross-sectional studies (10 multicenter), and one was a monitoring report of iodization programs that included a measurement before the introduction of iodized salt to a measurement after the introduction of iodized salt. In order to investigate the consistency of the relationship between iodine status as determined by UIC and Tg more clearly, for those studies that reported this information for more than one group, we considered each of these groups separately (i.e., one study of pregnant women and their newborns (37); one study of pregnant women and adults (38); one study of children and adults (30); three studies of children living in different regions (39) or countries (40,41); and seven studies of adults living in different regions (21,25,(42)(43)(44) or countries (45,46)). …”

“…Seven studies (21,25,30,38,43,45,46) showed that iodine deficient adults had a median Tg ‡13 lg/L (range 16-69 lg/L), while only one study (45) reported that iodine-sufficient adults had a median Tg ‡ 13 lg/L. However, 8 of 12 studies (21,25,(42)(43)(44)72,90,91) reported that adults who were categorized as iodine deficient had a median Tg <13 lg/L. One of these studies (42) included adults with iodine excess (i.e., median UIC ‡300 lg/L) who, in contrast to the findings of Zimmermann et al (41) in schoolchildren, had a median Tg <13 lg/L.…”

“…In iodine deficiency, an increased amount of Tg is released into the blood (20), which is positively correlated with thyroid volume (21). For example, healthy adults have a mean Tg concentration ranging from 5 to 14 lg/L (22)(23)(24)(25)(26)(27). In contrast, adults with endemic goiter have a mean Tg ranging from 94 to 208 lg/L (28)(29)(30).…”