Dystrophia myotonica and hypothyroidism.

Two cases of dystrophia myotonia associated with hypothyroidism are reported. This association is not frequent. In both cases the hypothyroidism precipitated an otherwise mild muscular weakness due to dystrophia myotonia. Treatment with dried thyroid improved the muscular power, while the myotonia remained unchanged. Since dystrophia myotonica and hypothyroidism have many presenting symptoms in common, a complete assessment of the thyroid function in every case of dystrophia myotonica seems worthwhile.