Global TcTU was determined in 568 patients without any specific thyroid drug intake
- 54 with normal thyroid, 274 with goitre and euthyroidism and 240 with thyroid autonomy.
57 patients with autonomy and overt hyperthyroidism were the only group with TcTU
values significantly higher than normals. Common to all groups was a large scatter
of the TcTU values. In 332, the effects of individual iodine supply were studied by
measuring the iodine concentration in spot urine samples. There was a significant
inverse correlation between the TcTU values and the urinary iodine excretion in the
groups of normal thyroids and of goitres with euthyroidism. In the group with autonomy
an effect of iodine supply could only be seen in cases of greatly increased urinary
iodine excretion, resulting in very low TcTU values. Out of 20 patients with autonomy
and iodine contamination, only 4 showed overt hyperthyroidism. The large scatter of
TcTU values in all groups may be explained by the persistent iodine deficiency as
well as by the frequent exposure to unknown amounts of iodine in patients with thyroid
disease. Therefore, the spontaneous TcTU alone cannot identify a small group of patients
with autonomy and high risk of iodine-induced hyperthyroidism, from a very large group
of patients with goitre.
