Are serum neopterin concentrations superior to other parameters in the differential diagnosis and prognostic assessment of Graves' disease ?

There is a lack (1.) of a single criterion for the definitve differentiation between immunogenic (IH) and non-immunogenic hyperthyroidism (NIH), and (2.) also a lack of an unequivocal prognostic predictor for the individual course of patients with immunogenic hyperthyroidism. In 152 patients scheduled for iodine-131 therapy, serum neopterin concentrations were measured using a commercially available RIA, and the neopterin concentrations of IH (n = 84) and NIH (n = 42) patients were compared. Of these patients, 83 and 26 per cent respectively were treated with antithyroid drugs which did not have a significant impact on neopterin levels. In patients with IH and NIH, the concentrations [mean ± SD] of neopterin were 1.89 ± 0.79 μg/l and 1.98 ± 0.9 μg/l, respectively (p = 0.4). After therapy with iodine-131, 28% of the IH-patients were euthyroid, 32% hyperthyroid, and 40% hypothyroid. In finally euthyroid patients, pretherapeutic neopterin concentrations were higher (3.1 ± 2.8 μg/l) than in finally hyperthyroid (1.8 ± 0.7 μg/l), or hypothyroid (1.6 ± 0.7 μg/l) patients. These results argue against a relevant clinical role of neopterin concentrations for the differential diagnosis of IH versus NIH in these patients. However, a prognostic significance of neopterin concentrations in patients with IH is suggested.