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Epidemiology of multinodular toxic goitre |
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Hyperthyroidism is an important clinical consequence of multinodular goitre and a characteristic manifestation of the disease. The importance of iodine intake for the development of the disorder, even in non-endemic areas has been demonstrated in comparative epidemiological studies in Jutland, Denmark with mild to moderate iodine deficiency (but no endemic goitre in school children) and Iceland with a high normal iodine intake.
Fig. 6 shows the contribution of various types of disease to the incidence of hyperthyroidism in the two areas. Multinodular toxic goitre was the most common type in the low iodine intake area, whereas it was the cause of only 6% of cases in the high iodine intake are. In Iceland the dominating cause of hyperthyroidism was Graves' disease, and in young subjects the incidence was several fold higher than in Jutland. The life time risk of developing Graves' disease was not much different as this was more common among the elderly in Jutland. Still, the dominating cause for the very high incidence of hyperthyroidism in the elderly in Jutland was multinodular toxic goitre (fig. 6).
Figure 6a:
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Relative contribution of different types of disease to the incidence of hyperthyroidism in Jutland with low and Iceland with high iodine intake. GD: Graves' disease, MNTG: multinodular toxic goitre, STA: solitary toxic adenoma, SAT: subacute thyroiditis. |
Figure 6b:
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Figure 6b Age-specific incidence rates of all types of hyperthyroidism in Jutland and Iceland. Data from 6 . ** p < 0.01, *** p < 0.001. |
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