Endocrine Abstracts

Introduction: We are presenting our results on the relationship between a concentration of urinary iodine (UI) and serum thyroglobulin (Tg) in population studies carried out on a general healthy total population that was randomly selected (individuals aged 6–98 years, 1751 males, 2420 females). 87.2% of the total population was described as the normal population with a simultaneously determined thyrotropin and free thyroxine within reference ranges.

Methods: The individuals were divided into subgroups with moderate and mild iodine deficiency, adequate, more than adequate and excessive iodine intake. The mean and median of Tg were calculated in these subgroups.

Results: Tg concentrations were dependent on gender, age and UI. Upper nonparametric tolerance limits of Tg in relation to iodine intake were calculated from individuals of the normal population, in which both the concentration of Tg and urinary iodine were within the normal reference range (Tg=0–85 μg/l, UI=100–200 μg/l). Tolerance limits were dependent on gender and age. The total value of tolerance limits is 44 μg/l; for individuals aged 6–17 years it is 39.1; 18–65 years =51.4 and 66–98 years =60.6 μg/l.

Conclusion: Tg seems to be a useful marker of iodine deficiency in a population, in which thyroid diseases are not too frequent. Our results also show that, under conditions of iodine deficiency, insufficient iodine intake is a factor that increases the concentration of Tg in the circulation and thus directly points to the fact that thyroid disorders are amplified by iodine deficiency. Children and the elderly are more affected. In general, Tg serum concentrations higher than 40 μg/l should be an indicator for determining urinary iodine.