The clinical features of myotonia dystrophica include various endocrinopathies, of which gonadal failure is the most frequently encountered.1
The frequency of thyroid abnormalities such as goiters and nodules is not generally appreciated. Previous works have shown that thyroid function as assessed by protein-bound iodine and thyroidal 131I uptake studies is normal. However, a low basal metabolic rate is found in about 60% of these subjects.2
The availability of synthetic thyrotropin-releasing hormone (TRH) and its effect on plasma thyroid-stimulating hormone (TSH) has provided an opportunity for more precise investigation of the hypothalamic-pituitary-thyroid axis in an attempt to further elucidate the hypometabolic state.
Twelve subjects (eight males and four females) with myotonia dystrophica were studied. All the patients were clinically euthyroid, but two of them had solitary "cold" thyroid nodules. One of these patients had a papillary carcinoma.
Sagel J, Distiller LA, Morley JE, Isaacs H. Normal Thyrotropin-Releasing Hormone Response in Myotonia Dystrophica. Arch Neurol. 1976;33(7):520. doi:10.1001/archneur.1976.00500070062018
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