Assessment of the Effect of Interferon-Beta1a Therapy on Thyroid and Salivary Gland Functions in Patients with Multiple Sclerosis Using Quantitative Salivary Gland Scintigraphy

Objective: Interferon-beta (IFN-β) is widely used in patients with multiple sclerosis (MS), a demyelinating disease of the central nervous system. High incidence of thyroid dysfunction has been reported after administration of IFN-β in MS patients. The aim of this study was to assess the effect of IFN-β1a therapy on simultaneous thyroid and salivary gland function in patients with MS using quantitative salivary gland scintigraphy (QSGS). Methods: Fifteen relapsing-remitting (RR) MS patients treated with IFN-β1a and two control groups consisting of 15 untreated RRMS patients and 20 healthy age and sex-matched individuals were included in the study. The functional status of the salivary and thyroid glands was analysed with the QSGS and laboratory tests, including thyroid function and thyroid antibody. After intravenous administration of 150 MBq Tc-99m pertechnetate, dynamic study was performed for 25 minutes. Salivary gland secretion was stimulated with oral lemon juice at 15 minutes. At the end of dynamic study, a static image in the same projection was taken. Uptake ratios at 12-14 min (UR%) and stimulated excretion fraction (EF%) of each parotid and submandibular gland were calculated automatically from SGS. Thyroid uptake ratio (TUR) of thyroid gland was calculated from the static image. Results: All MS patients treated and untreated with IFN-β1a, and healthy individuals were euthyroid. Anti-thyroid peroxidase antibody (anti-TPO) was detected in 4 out of 15 MS patients (26.6%) treated with IFN-β1a. There was no significant differences in the UR, EF and TUR values among MS patients treated and untreated with IFN-β1a, and healthy controls (p>0.05). Although the TUR values in MS patients treated with IFN-β1a were less than those of the both control group, the difference was not statistically significant (p>0.05). Conclusion: IFN-β1a therapy was demonstrated to have no effect on thyroid and salivary gland functions using QSGS in patients with MS. Thyroid and salivary gland functions were also found to remain unchanged in untreated MS patients.