Many studies have been carried out evaluating thyroid hormone parameters in patients suffering from various illnessess. However data on thyroid function after a recreation period are missing. Therefore we evaluated thyroid hormone parameters in 178 patients (mostly suffering from chronic obstructive lung disease) undergoing a four week recreation period in a health spa on the island Borkum at the North Sea. We observed a subtle, but significant increase in basal TSH concentrations from 1.20 mU/l (median) to 1.50 mU/l; (p<0. 001) and a fall in T4 values from 97.5 +/- 17.7 nmol/l (mean +/- SD) to 90.3 +/- 17.0 (p<0.001) and T3 from 2.21 +/- 0.33 nmol/l to 2.09 +/- 0.33 (p<0.001). However no increase in iodine intake occurred during the four weeks: median iodine excretion 61 microg iodine/g creatinine at the beginning vs 65 microg iodine/g creatinine at the end.
In conclusion: a recreation period at the North Sea is associated with subtle but significant changes in thyroid hormone parameters. However no increase in iodine intake occurs during the four week observation period.