Primary hyperthyroidism and associated hyperparathyroidism in a patient with myotonic dystrophy: Steinert with...

A patient with myotonic dystrophy and associated primary hyperthyroidism and hyperparathyroidism is described; this association has not been reported previously, to the authors' knowledge. The patient also suffered from hypergonadotropic hypogonadism and hyperinsulinism with insulin resistance. The etiology of hyperthyroidism and hyperparathyroidism is not clear. At surgery, a parathyroid adenoma was extirpated, and a subtotal thyroidectomy was performed. Postoperative course was unremarkable, with consistently normal serum calcium levels but persistently elevated serum parathyroid hormone concentrations. The possibility that the patient had a residual hyperparathyroidism could not be eliminated. Thyroid function was normal. After surgery, the patient reported subjective improvement in his muscle strength. The authors conclude that both diseases-- hyperthyroidism and hyperparathyroidism--exert a negative effect on the myotonic dystrophy and that an early recognition of these two diseases is crucial for the favorable evolution of the patient.