Summary
In hypothyroid patients serum soluble IL-2 receptor levels showed scattered and conflicting
results. In our report we studied circulating soluble interleukin 2 receptors in 22
patients with hypothyroid autoimmune thyroiditis before L-thyroxine treatment and
when the patients became euthyroid. The mean of soluble Interleukin 2 receptor levels
in the hypothyroid state was 48.6 pmol/l (95% confidence interval, 45.6-51.5) statistically
lower than in the controls (95% confidence interval, 86.4 pmol/l, 83.3-89.4) (p <
0.0001). When the patients became euthyroid during L-thyroxine treatment, soluble
Interleukin 2 receptor levels increased, showing mean values comparable to the controls.
A positive high correlation (p<0.001) was observed between soluble Interleukin 2 receptor
levels and thyroxine free levels in the hypothyroid as well as in the euthyroid state
and between soluble Interleukin 2 receptors and the mean weekly L-thyroxine dose.
Our study confirmed that in the hypothyroid state, the behaviour of soluble Interleukin
2 receptors is anomalous as compared to other autoimmune diseases. In fact a strict
relationship exists between the levels of thyroid hormones and soluble Interleukin
2 receptors but not between the latter and antithyroid antibodies. These results agree
with those supporting a role for thyroid hormones in the regulation of the immune
system. They also suggest that the measurement of soluble Interleukin 2 receptors
could be used as a marker of the peripheral action of thyroid hormones.
Key words
Hypothyroid Autoimmune Thyroiditis - IL-2 Receptor - L-Thyroxine - Antithyroid Antibodies
