Regression of Endemic Goitre and of Changes in Iodine Metabolism during 10–15 Years in the East of Finland

Abstract

In Savonlinna in the east of Finland in 1959 the thyroid uptake was 60–70% in control subjects and in patients with nontoxic goitre (NTG) and with hyperthyroidism and the urinary excretion of stable iodine was 45–60 µg/day. Fourteen patients with NTG, 3 hyperthyroid patients and one healthy control subject were studied in greater detail. The thyroid turnover was normal in NTG with the exception of two patients in whom it was increased. The faecal excretion of iodine was 20 µg/day, the renal iodine clearance 37 ml/min and the calculated iodine concentration in the iodide compartment 0.75–0.90 µg/l. The distribution of ¹³¹I was similar in the control subject and in NTG patients. In a few patients substantial proportions of precipitable iodine were found in the urine and non-butanol-extractable iodine in the blood. In 1969 the uptake was 30–34% in controls and euthyroid goitre patients. The urinary excretion of iodine was 219 µg/day. The goitre incidence in school children in Savonlinna and the surrounding communities was generally 1%, in two communities 6 and 13%, respectively. The figures are markedly lower than those reported in the early 1950s (15–30%). It is concluded that owing to intensified iodine prophylaxis during the last 10 years the endemic goitre is rapidly regressing in this area.

Further decrease in thyroidal uptake and disappearance of endemic goitre in children after 30 years of iodine prophylaxis in the east of Finland

“…In addition to iodine deficiency (Adlercreutz 1928;Wahlberg 1938;Vilkki 1956;Lamberg et al 1958Lamberg et al , 1962Lamberg et al , 1970 naturally occurring goitrogens present in cow's milk may have played an additive role (Arstila et al 1969). Furthermore, part of the patients conside¬ red as having simple goitre may in fact have had autoimmune thyroiditis.…”

“…Hg a day and in 1979 is was not far from 300 ug a day when the faecal loss of some 15-20 ¡xg a day (Lamberg et al 1970) is taken into account. House¬ hold animal feeds have been iodized in Finland for many decades which was the reason why milk products were the main source of iodine in the 1950's.…”

“…The 24 h thyroid uptake of 131I was measured with a usual routine method. The daily urinary excretion of stable iodine was measured according to the method previously described (Lamberg et al 1970) from a 24 h urine sample.…”

“…After studies carried out in the 1950's the region of Savonlinna, a city in the east of Finland, was chosen for continuous follow-up. The first study was carried out in 1959 (Lamberg et al 1962) and a 10-year follow-up in 1969 (Lamberg et al 1970). During this period marked changes were seen in the iodine metabolism and the incidence of goitre in school children.…”

“…In 1979 a 20-year followup study was carried out which forms the basis of the present report. (Lamberg et al 1962(Lamberg et al , 1970 in three categories: I: 8 patients, II: 4 and III: 7 patients. Twelve of the patients had nodular, and 4 of them multinodular goitre.…”