[Thyroid function in a population with an extra iodine intake]

After 20 years of iodine salt fortification, the prevalence of goiter has decreased significantly in the rural area of Pirque, central Chile. In this location, equipment has been installed that efficiently and economically adds 0.5 mg of elemental iodine per liter of water to render it potable.

To study thyroid function and urinary iodine excretion in school age children of this zone, after two years of extra iodine intake.

One hundred thirty four children aged 6 to 12 years old were examined. In 56 randomly chosen children a morning urine sample was obtained to measure iodine excretion. In 45 children without goiter, a blood sample was drawn to measure TSH and thyroxin.

In nine children (7%) a diffuse goiter was found. Median urinary iodine excretion was 158 micrograms/dl. Thyroxin and TSH levels were within normal limits (8.4 +/- 1.1 micrograms/dl and 2.2 +/- 1.5 microU/ml respectively). During the period of iodine water supplementation there were 47 births in the zone. All newborns had normal TSH values and none had goiter.

When present results are compared with the period before water iodination (when the prevalence of goiter was 9.6% and mean urinary iodine excretion was 57.6 micrograms/dl), it can be concluded that extra iodine intake in this rural population has not caused additional thyroid problems.