OBJECTIVETo study the dose-response relationship between the quantitative morphological stereology on thyroid and different iodine doses in mice.

METHODSWeaning Kunming mice were randomly divided into seven groups. The mice were fed for 100 days with distilled water containing different KIO3 concentrations, i.e. 50, 250, 500, 1 000, 1 500, 2 000, and 3 000 microgram/L respectively. The 50 microgram/L (proper iodine concentration) group was control group, and the groups of 250 approximately 3 000 microgram/L were high iodine groups. The stereology parameters of thyroid follicle and follicular cavities were measured with HPIAS-1000 (High Resolution Pathological Image & word Analysis System). The stereology parameters included mean surface, volume on area, volume on circumference, specific surface, numerical density on area, spherical factor, the percentage of mean surface and mean volume of the follicular epithelial cell in thyroid follicle was further calculated.

RESULTSPositive correlations was observed between the thyroid absolute and relative weight, goiter rate and different iodine doses. And the thyroid absolute and relative weight of mice in the 250 microgram/L group was significantly different from that in 50 microgram/L group. The goiter rate of mice in different high iodine groups was in conformity with that of epidemiological investigation. The goiter rate of mice in 500 microgram/L group was different from that in 50 microgram/L group. Positive correlations were observed between mean surface, volume on area, volume on circumference, spherical factor and iodine doses, but the negative correlations were observed between numerical density on area, specific surface, the percentage of mean surface and mean volume of the follicular epithelial cell in thyroid follicle and iodine doses.

CONCLUSIONSWhen Iodine doses are between 250 approximately 3 000 microgram/L, the dose-response relationship was observed between the morphological stereology parameters of thyroid follicle and follicular cavities and iodine doses, and when the dose of iodine is 250 microgram/L, it is possible to induce colloid goiter of mice. The goiter rates of mice resulted by different high iodine doses were in conformity with that of the epidemiological investigation of people.