Salivary Function after Radioiodine Therapy: Poor Correlation between Symptoms and Salivary Scintigraphy

Abstract

ObjectiveSymptoms of salivary gland dysfunction frequently develop after radioactive iodine (RAI) therapy, but have generally not been correlated with assessment of salivary gland functioning. The aim of this study was to determine whether there was a correlation between salivary symptoms and salivary functioning as assessed by salivary scan parameters.MethodsThis was a non-randomized observational study. Fifteen patients receiving RAI therapy for differentiated thyroid cancer completed a questionnaire assessing their salivary and nasal symptoms prior to their therapy and 3 and 12 months after their therapy. Salivary gland scanning using technetium-99m pertechnetate was performed at the same time points. In addition, protective measures used at the time of radioiodine administration, such as use of fluids and sour candy, were also documented. Measures of salivary gland accumulation and secretion were correlated with scores of salivary and nasal symptomatology and any effects of protective measures were assessed.ResultsThe mean number of salivary, nasal, and total symptoms at 3 months increased significantly over the number of symptoms at baseline by 3.7, 2.7, and 6.3 symptoms, respectively (p values 0.001, 0.0046, and <0.001, respectively). The mean increases in the number of salivary, nasal, and total symptoms at 12 months were non-significant at 1.3, 1.3, and 2.5 symptoms, respectively. The mean right parotid gland accumulation and secretion of radioisotope declined significantly at 3 months, compared with baseline. The changes in left parotid and right and left submandibular function were non-significant. There was no association between the increase in salivary, nasal, or total symptoms and the change in scintigraphy measures. However, the increases in nasal and total symptoms were significantly greater in those with co-existent Hashimoto’s disease, compared with those without this condition (p values 0.01 and 0.04, respectively). Nasal symptoms decreased (p value 0.04) and total symptoms trended to decrease (p value 0.08) in those who used sour candies, compared with those who did not. Increasing body mass index was significantly associated with increasing nasal symptoms (p value 0.05). Greater decline in salivary parameters at 3 months compared with baseline was generally associated with heavier body weight, decreased thyroid cancer stage, absence of Hashimoto’s thyroiditis, and pre-menopausal status.ConclusionSalivary and nasal symptoms increased and salivary scintigraphy parameters decreased after radioiodine therapy. However, the increased symptoms did not correlate with decrements in salivary gland accumulation or secretion. Moreover, the variables associated with symptoms and changes in salivary scan parameters differed. Therefore, a better understanding of the relationship between salivary gland symptoms and functioning is needed. Factors affecting susceptibility to salivary and nasal damage after radioiodine therapy need to be better elucidated, so that modifiable factors can be identified.

Radioactive Iodine Administration Is Associated with Persistent Related Symptoms in Patients with Differentiated Thyroid Cancer

“…The lack of this tool motivated us to develop a web-based survey to evaluate the presence of early and late RAI related symptoms, including the 12 most frequently published in previous studies [12, 13, 15, 16]. The aim of these surveys was to study both the frequency and intensity of these RAI related symptoms.…”

“…These surveys were created by our team based on information published in literature regarding RAI related symptoms [12, 13, 15, 16]. Early RAI related symptoms were assessed within 6 months after initial treatment (considering RAI administration date in patients who received RAI or surgery date in those who did not receive RAI).…”

“…More frequently, RAI can impact nonthyroidal tissues that express sodium iodide symporter (NIS), including the salivary glands and lachrymal system [11]. Salivary glands dysfunction occurs with an incidence that varies from 5 to 86% [12]. Dysfunction may appear as salivary gland pain, taste impairment such as hypogeusia, also xerostomia, sialolithiasis, dental caries, stomatitis, salivary gland or oral infections, facial nerve damage, and even salivary gland neoplasia [12].…”

“…Salivary glands dysfunction occurs with an incidence that varies from 5 to 86% [12]. Dysfunction may appear as salivary gland pain, taste impairment such as hypogeusia, also xerostomia, sialolithiasis, dental caries, stomatitis, salivary gland or oral infections, facial nerve damage, and even salivary gland neoplasia [12]. These side effects may be persistent in nearly 7% of patients and profoundly impair patient quality of life (QoL) [13, 14].…”

“…Although tissues in the nasal cavity do not express NIS, RAI may be transported nonspecifically from the lachrymal system into the nasal ducts [12]. Several nasal complaints have been documented including nasal pain, nasal tenderness, bloody discharge, and dry nose, with a frequency up to 10.5% [16].…”