Active moderate-to-severe thyroid eye disease (TED) is a major therapeutic challenge. Pulse therapy with intravenous glucocorticoids is the standard treatment, with variable response. Radioactive iodine therapy (RAI) was reported as a risk factor for onset or worsening of TED. We evaluated putative predictive factors for response to intravenous methylprednisolone in patients with active TED.

Data were collected for 64 consecutive patients (45 women) with active moderate-to-severe TED treated with a minimum cumulative dose of 4.5g methylprednisolone. Patients were classified as responders (R) or non-responders (NR) on Clinical Activity Score (CAS), and clinical features were compared between groups.

Sixty-two patients had Graves’ disease (GD), and 2 had Hashimoto's thyroiditis (HT). Median age at thyroid dysfunction diagnosis, TED manifestation and pulse therapy was 46, 48 and 51 years, respectively; 56.2% were euthyroid when TED manifested. Among them, 73.4% were responders. R and NR were comparable for gender, age, thyroid function, serum antibodies, disease duration, pre-treatment CAS, smoking, lipid profile, and adverse events. Forty-nine patients were treated with RAI for GD: 15 before the active phase of TED (before pulse therapy), 16 during, 17 after, and 1 both before and after pulse therapy. Response rate was higher in patients who received RAI during than after pulse therapy (P=0.032) and similar to those not treated with RAI at all (P=0,599).

Pulse therapy was effective in the majority of patients. The only factor associated with response to pulse therapy was the timing of RAI, suggesting that it seems to be safe when used concomitantly with pulse therapy.