Endocrine Abstracts

Introduction: In a prospective study we determined factors affecting GO activity and poor response to glucocorticoid therapy in patients treated with radioiodine (131-I group) or with anti-thyroid drugs (ATD group).

Material and methods: The ATD and 131-I groups consisted of 168 patients (mean age 52.2±11.2 years) and of 46 patients (mean age 52.1±13.3 years), respectively. SoluMedrol pulses (8.0 g) were applied, followed by orbital irradiation (20 Gy). Levels of TSH, FT₄, and TRAb, CAS and IO were evaluated in all patients prior to treatment, and 1, 6, and 12 months after.

Results: Age, sex, GO duration, IO, CAS and FT₄ levels were similar in patients of both groups. In the 131-I group TRAb levels were significantly higher over the course of observation (P<0.05). As evaluated using logistic regression, pre-treatment TRAb concentration was related to severe GO (IO≥5) only in the 131-I group (RR=1.047, 95% CL=1.003–1.092, P≤0.05). Poor responders were 69/167 of ATD and 13/46 of 131-I patients who required further oral glucocorticoids following SoluMedrol pulses. Only pretreatment TSH and IO were predictive of poor response (P<0.05), with IO ≥6 threshold, as based on discriminant analysis (sensitivity 0.47, specificity 0.71). In the ATD group, IO was found to be correlated with TRAb concentration at 0, 1, and 6 months (P<0.05; e.g. for TRAb-0 vs IO-0, r=0.326). In the 131-I group, correlation was stated between TRAb concentration and IO over the time of observation (P<0.05, e.g. TRAb-12 vs IO-12, r=0.436).

Conclusions: Pretreatment TRAb is predictive of risk of severe GO only in 131-I patients. Pretreatment TSH and IO are risk factors of being a poor responder to glucocorticoid therapy in ADT and 131-I patients. Correlation between TRAb and IO was found in both groups.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.