Objective Evidence of Impaired Salivary Function in Patients with Autoimmune Thyroiditis Using Quantitative Salivary Scintigraphy: A Preliminary Report

Abstract

Background: It has been speculated that impaired salivary flow contributes to autoimmune thyroiditis (chronicthyroiditis,Hashimoto's thyroiditis).To test this hypothesis, salivary function was measured by quantitative salivary scintigraphy in autoimmune thyroiditis patients, as well as in age-and sex-matched controls for comparison. Methods: Forty patients with autoimmune thyroiditis history of over 10 years and 36 healthy controls were enrolled in the study. All of the 40 autoimmune thyroiditis patients had good blood sugar control. None presented with autonomic neuropathy. These 40 autoimmune thyroiditis patients were separated into two subgroups. Group 1:20 patients with xerostomia, and group 2:20 patients without xerostomia .After intravenous injection of 5 mCi 99mTc-pertechnetate,sequentialimages at 1 minute/frame were acquired for 30min.The 1st and 15th minute uptake ratios(UR)were calculated from the tracer uptakes in the four major salivary glands over the background ROIs. Saliva excretion was stimulated by 1 tablet of 200 mg ascorbic acid given orally 15 min post-injection of the tracer. Then, the maximal excretion ratios(ER)of the four major salivary glands after sialagogue stimulation were calculated. Results: Impaired salivary function, represented by significantly decreased UR and ER values ,in autoimmune thyroiditis patients with xerostomia was demonstrated in this study. Conclusion: Significantly poorer salivary function was found in autoimmune thyroiditis patients with xerostomia, when compared with autoimmune thyroiditis patients without xerostomia and healthy controls, via objective and quantitative salivary scintigraphy. However, a larger series of autoimmune thyroiditis patients is necessary to confirm our findings.