Endocrine Abstracts

This communication tests the hypothesis that iodine (I2) gas or iodine oxides released from seaweeds previously shown to enhance atmospheric iodine adjacent to seaweed hotspots, may through being inspired by respiration, supply a significant fraction of daily iodine requirements. This could assume importance in a country such as Ireland where iodised salt availability is <5%. Iodine intake was assessed by measuring urinary iodine (UI) excretion using a dry ashing technique with Sandell Kolthoff colorimetry. Urine samples were obtained from schoolchildren (n=167) and adult (n=481) populations living in coastal areas, including those residing beside a seaweed hot spot, and inland areas of Ireland. Despite dietary iodine intake not varying significantly between inland and coastal communities, the median UI values in the inland areas was 72.5 μg/l (range 58–102 μg/l); coastal areas with limited seaweed growth 70.8 μg/l; seaweed hot spot 145 μg/l. The % of individual readings suggestive of iodine deficiency (<50 μg/l) were greatest in inland areas 27.9 vs 14.3% in limited seaweed growth areas. The lowest proportion of UI values <50 μg/l (3.6%) was observed in the population living beside the seaweed hot spot. Not surprisingly, the greatest number of UI values >150 μg/l (45.6%) was observed in the seaweed hot spot region. In contrast, relatively few higher UI values (>150 μg/l) occurred in the other regions (range 3.6–11.6%). It is postulated that the most infrequent evidence of iodine deficiency recorded near seaweed hotspots may be the result of atmospheric iodine compensation for inadequate dietary iodine intake through respiration in coastal areas and may assist in maintaining normal thyroid function even when dietary intake is apparently deficient.