Increased Serum Neopterin Levels in Patients with Graves' Disease

Summary

Neopterin (NPT) a marker of activation of the T-lymphocyte/monocyte axis has been measured in serum of 89 patients with autoimmune thyroid disease (72 patients with Graves' disease and 17 patients with autoimmune thyroiditis) and compared to a group of 24 normal controls and 24 patients with nontoxic goitre. There was a significant correlation between NPT levels and age in the patients with nontoxic goitre (r = 0.447, p< 0.001) but not in patients with autoimmune thyroid disease. Significantly higher NPT levels were found in all patients with Graves' disease (GD) compared to age and sex matched healthy controls, and patients with nontoxic goitre (5.7±2.4 vs 4.1 ±1.7, and 4.0±1.5, p<0.01). However, there was no difference in NPT levels between each group of patients with GD when subdivided in: hyperthyroid newly diagnosed GD, treated GD, GD in remission and relapse. Patients with autoimmune thyroid itis did not have abnormal NPT levels compared to age and sex matched normal controls. Neopterin serum levels were not influenced by hyperthyroidism as no significant differences in NPT levels could be found in 24 patients with hyperthyroid Graves' disease and 13 patients with toxic goitre or toxic adenoma when compared to age and sex matched euthyroid patients with Graves' disease or normal controls. Moreover, there was no significant difference in mean NPT levels 1. before and after restoration of euthyroidism in 10 patients with hyperthyroid Graves' disease and 2. before and under T3 supplementation in 18 patients with Graves' disease in remission who underwent a T3 thyroid suppression test. We conclude that 1. Graves' disease is associated with higher NPT serum levels, however its measurement is not able to differentiate the various clinical states of the disease, 2. thyroid function does not affect NPT production in serum and 3. age should be taken into consideration when using NPT serum measurement as marker of immune activation in thyroid disease.

Key words

Neopterin - Graves' diesease - Hashimoto's thyroiditis - Thyroid status