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It has been reported that methimazole (MMI) interferes unfavourably
with subsequent treatment with radioactive iodine. Aktuna, Graz,
Austria, administered 40 mg MMI daily to 11 goiter patients until surgery
and in another 11 patients MMI was discontinued 5 days before surgery (Gr
I and II respectively). MMI and its metabolite 3-methyl-2-thiohydantoin
(MTH) were measured in thyroid tissue after operation. It was found that
even in group II a substantial amount of MMI was present in thyroid tissue
in contrast to MTH, which was only detected in thyroid tissue of group
I. It is suggested that maybe MTH is the prefered antithyroid agent as
theoretically it should not interfere with subsequent RAI treatment when
stopped a few days before.
Ward et al, Campinas and Sao Paulo, Brasil, followed patients who were longterm treated with 400 mg amiodarone daily because of life threatening cardiac arrhythmias. Fourteen/97 patients (aged 32-69yrs.) had pre-existing goiter. Thyroid function tests were done at 3 months intervals. In 83patients without goiter 52/83 had always normal function tests; 23/83 had elevated TSH that persisted in 15 patients and normalized in the others during amiodarone treatment. T4 and FT4 were normal in 83 patients with few exceptions of mild abnormality; 8/83 had low TSH that normalized in 6. In 14 patients with goiter 7/14 had always normal thyroid tests; 4/14 had elevated TSH after the first visit that normalized in 3/14. In none of 97 patients it was necessary to discontinue amiodarone and arrhythmias were kept well under control. (Comment: This communication suggests that amiodarone does not frequently cause serious thyroid abnormalities, but other reports do suggest that amiodarone may be dangerous in a substantial percentage of patients, either due to induction of hypo- or hyperthyroidism. It is therefore advisable to still use amiodarone only when other anti-arrhythmic drugs do not show sufficient effect, and, if administation is necessary to follow patients carefully.) In line with absent increased risk for hipfracture in postmenopausal women treated with thyroid hormone, are the results communicated by Marcocchi et al., Pisa, Italy, but then regarding males treated with suppressive doses of L-thyroxine. They found no difference in bone mineral density between these patients and matched controls, when measured in L2-L4, femoral neck, Ward's triangle and trochanter. (Comment: Most studies dealing with the possible risks of T4 treatment for osteoporosis and increased bone fractures are performed in postmenopausal women. The results of these studies are not yet fully conclusive but tend to show that risks are low or absent. The present communication concerns suppressive T4 treatment in males, apparently without risk for development of osteoporosis.) |
