Endocrine Abstracts

Background: Radioiodine (RAI) is highly effective in the treatment of hyperthyroidism. Lithium reduces thyroidal release of organic iodide and thyroid hormones, thus increasing thyroid retention of RAI and subsequently, the delivered dose of radiation. Controversy surrounds whether lithium increases the efficacy of RAI.

Aims: To assess whether lithium improved outcome after radioiodine treatment and analyse fT4 and eye disease changes in lithium treatment patients.

Methods: In a double blind study, 65 patients, aged between 24 and 77, were randomised to receive either lithium or placebo in conjunction with RAI therapy. Thyroid function and serum lithium concentration were measured 9 days prior to RAI and on follow up at 1, 3, 6, 9 and 12 weeks post-RAI. Urinary iodine excretion was calculated from 24 h urine collections nine days prior to RAI and immediately after. The presence and severity of eye disease was noted one month prior to and one month after RAI treatment. Local Ethics Committee approval was obtained.

Results: At one year post-RAI, there was no significant difference between groups in numbers cured (87.5% in the lithium group; 87.8% in the placebo group; P=0.96) or in the time it took patients to become hypothyroid post-RAI (lithium group took a mean of 47.4±37.26 days compared to 48.9±31.16 in the placebo group; P=0.87). Placebo treated patients experienced a mean increase in fT4 post-RAI (1.61±10.36 pmol/l), while the lithium treated group experienced a mean decrease (−1.39±8.32 pmol/l); however this was not significant (P=0.23). Lithium did not effect eye disease progression (P=0.45). There was no difference in urinary iodine excretion between the groups (P=0.95).

Conclusions: Lithium did not significantly improve RAI treatment in this trial.