Effect of selenium administration for the protection of the salivary glands during radioiodine therapy

Objectives The impairment of the function of the salivary glands (SG) is a common chronic complication during radioiodine therapy (RIT) of the thyroid gland, which shows a positive correlation with the administered activity. Since selenium is discussed as a protective factor for SG (1,2), we examined the effect of a preventive single dose administration of selenium directly before starting a high-dose RIT

Methods 20 patients (group A) aged between 34-75a (mean: 53.7) treated with 3000-6000 MBq (mean: 3357) I-131 received a single oral dose of 1000 µg selenium thirty minutes before radioiodine capsule administration. The control group B consisting of 20 patients aged between 34-83a (mean: 64.4) received 3000 MBq (mean 3000) without selenium administration. As the uptake of Tc-99m-pertechnetate represents the function of the SG (3) the function of the SG was investigated non-invasively using SG scintigraphy before RIT and three months afterwards. Furthermore the selenium concentration in plasma was measured before the RIT and 72 hours afterwards

Results The mean blood selenium level in the intervention group A before the RIT was 72.67 mg/dl (57.0-91.0) compared to 103.44 mg/dl (73-134) after the RIT (p-value=0.001). The mean ^99mTc-pertechnetate uptake of the SG of group A was 0.20%±0.11% (0.07%-0.45%) before therapy and 0.22%±0.09% (0.06%-0.35%) after RIT. For the control group 0.17%±0.04% (0.09%-0.26%) before and 0.09%±0.04% (0.04%-0.18%) after the RIT. This means that for group A no significant loss of the SG function was found (p-value=0.93). In contrast a significant decrease in SG function was detected in the control group B (p<0.01)

Conclusions Our investigation suggests that selenium administration effectively protect the SD during RIT. To confirm this result we are in the process of evaluating the outcome of a larger patients’ collective