Endocrine Abstracts

Lithium blocks the release of organic iodine and thyroid hormone from the thyroid gland without affecting thyroidal radioactive iodine (RAI) uptake. From August 2001, we have been using lithium carbonate 800mg nocte as an adjunct to RAI treatment for thyrotoxicosis. Antithyroid medication is stopped and lithium started 3 days before RAI. Lithium is continued for 10 days in total with levels checked at 3 and 10 days. Thyroid function tests (TFTs) are measured 1, 3, 6, 9 and 12 weeks following RAI. Our standard follow-up is by telephone with thyroxine 100mg added once FT4 is <14.0 pmol/l.

We have previously reported our initial results using adjunctive lithium. At the time this led to an improvement in our cure rate from 78% to 100% (71, patients, mean follow-up 7.5 months). We now present an update on our clinical outcome (118 patients (26 M, 92 F) treated with lithium and radioiodine). Our cure rate with adjunctive lithium in this group is 93%.

Subsequently, we have started a prospective, randomised, double-blind, placebo-controlled trial (lithium vs. placebo, protocol as described above). To date we have enrolled 27 patients (5 M, 22 F), and 25 of these have reached 12 weeks. So far 22 of the 25 are hypothyroid on replacement, giving an overall cure rate of 88% in this prospective unblinded study.

Our retrospective data supports the use of lithium carbonate as an adjunct to RAI treatment.