| Rovet et al., Toronto, Ontario, Canada, conducted a longitudinal follow-up study in infant offspring of women who were hyperthyroid and were treated with PTU during pregnancy, to test if PTU treatment of the mothers had any effect on cognitive development. This prospective study is still going on, but preliminary findings were reported on a subset of 25 exposed and control infants. Attention, in PTU exposed infants at 6 months of age, indicated slower reaction times and more variable responses than in controls. Mental development otherwise (Bayley Mental Development Index) at 12 and 18 months showed no differences. It is concluded that in PTU exposed children attentional disorder may be induced but intelligence is not affected. Azizi et al., Teheran, Iran, evaluated the effect of methimazole therapy of lactating mothers on intellectual development of suckling infants. 139 Thyrotoxic lactating mothers and their infants were studied, 51/139 mothers were treated during pregnancy and during lactation, whereas 88/139 only took methimazole during lactation. Thyroid function parameters were taken at regular intervals during 12 months. IQ, verbal and functional components (Wechsler and Goodinof tests) were performed at age 4-6 years in 13 infants and 17 controls. Overall results were that even in mothers taking a dose of 20 mg methimazole per day thyroid function in suckling infants remained normal and the prevalence of thyroid antibodies was not different from controls. Mean IQ and verbal and mean performance and their components between infants exposed to methimazole and controls were not significantly different. The authors conclude that up to 20 mg methimazole per day taken by the mother there is no reason to discontinue breast-feeding of the infant. (Comment: Although this message is good news, we should realize that cognitive tests were done in only 13 infants so that higher numbers of infants exposed to methimazole are certainly necessary before more definite conclusions can be drawn.) Gunton et al., Sidney, Australia, assessed the frequency of positive serum antineutrophil cytoplasmic antibodies (ANCA) in 30 patients who received antithyroid drugs for more than 18 months. In 8/30 patients, ANCA positive results were present, 7/8 had recent PTU exposure and past carbimazole exposure, 1/8 had carbimazole exposure alone. Positive ANCA was associated with longer duration of PTU but not of carbimazole. Although ANCA positive vasculitis associated with antithyroid drug treatment is a rare complication, the authors conclude that if antithyroid drugs are indicated for long-term therapy, carbimazole may be preferred over PTU. (Comment: The finding of these authors, when confirmed in a larger study, may have therapeutical consequences indeed for long-term antithyroid drug treatment.) |
