Comparison of urinary iodine excretion and thyroid volume in students with or without constant iodized salt intake

Summary

We compared the iodine excretion and thyroid volumes in young students with or without continuous use of iodized salt in household. Students from five different Universities in Bavaria were evaluated on a voluntary basis. Exclusion criteria were age above 35 years, known thyroid illness except simple goiter, application of x-ray contrast medium within the last 6 months or other known exposure to high doses of iodine. The participants answered a questionnaire indicating permanent utilization of iodized salt for more than one year during all their meals, the intake of iodide tablets and eating in student cafeterias, offering meals that are prepared with iodized salt. Morning spot urine was drawn from each participant to measure creatinine correlated iodide excretion and thyroid volume was measured by ultrasound.

In this study, 932 students could be included, mean age was 24 years, 501 females, 431 males.

Chronic users of iodized salt were 75.9% (80.4% females, 70.5% males), 1.7% were on iodide tablets (200 μg/day) and 2.6% were on TSH suppressive therapy with thyroid hormones. The mean iodide excretion in chronic iodized salt users was 72.0 (±68.7) μg/g creatinine compared to non-users 66.0 (±65.4) μg/g creatinine (p < 0.003). Those students who were on iodide tablets had a mean iodide excretion of 130.0 ± 72.0 μg/g creatinine. Mean thyroid volume was 14.1 (4.4 – 44.1) ml in females and 17.1 (6.6 – 64.4) ml in males, solid thyroid nodules were detected in 5.9% and thyroid cysts in 2.7% of the participants without any difference between iodized salt users or non-users.

Key words

Iodized salt - urinary iodine excretion - goiter incidence