Objective evidence of decreased salivary function in patients with autoimmune thyroiditis (chronic thyroiditis, Hashimoto's thyroiditis).

Impaired salivary flow is found in Sjögren's syndrome, which is a common, chronic, autoimmune, inflammatory connective tissue disease, mainly affecting the exocrine glands. Histopathologically, lymphocytic infiltrations of the salivary glands are found in Sjögren's syndrome that are similar to those of the thyroid gland in autoimmune thyroiditis (chronic thyroiditis, Hashimoto's thyroiditis). To test this hypothesis by Daniels et al ., salivary function was measured by quantitative salivary scintigraphy in autoimmune thyroiditis patients, as well as in age- and sex-matched controls. Forty patients, each with a history of autoimmune thyroiditis of over 10 years, and 61 healthy controls were enrolled in the study. All of the 40 autoimmune thyroiditis patients had good blood sugar control. None presented autonomic neuropathy. They were separated into two subgroups: patient group 1, 20 patients with xerostomia; patient group 2, 20 patients without xerostomia. Two control groups of healthy subjects were included for comparison: control group 1, 36 subjects without xerostomia; control group 2, 25 subjects with xerostomia. After intravenous injection of 5 mCi (99m)Tc-pertechnetate, sequential images at 1 min per frame were acquired for 30 min. The first and 15th minute uptake ratios (URs) were calculated from the tracer uptakes in the four major salivary glands relative to the background regions of interest (ROIs). Saliva excretion was stimulated by one tablet of 200 mg ascorbic acid given orally 15 min after injection of the tracer. The maximal excretion ratios (ERs) of the four major salivary glands after sialagogue stimulation were calculated. Impaired salivary function, represented by significantly decreased UR and ER values, in autoimmune thyroiditis patients with xerostomia was demonstrated in this study. Significantly poorer salivary function was found in autoimmune thyroiditis patients with xerostomia, when compared with autoimmune thyroiditis patients without xerostomia and healthy controls with or without xerostomia, via objective and quantitative salivary scintigraphy. However, a larger series of autoimmune thyroiditis patients is necessary to confirm our findings.