The estimation of mean potential duration in endocrine myopathy

Abstract

The mean potential duration of the deltoid muscle was measured in 17 patients with endocrine disturbances. These disturbances included 10 cases of thyrotoxicosis, four cases of Cushing''s Syndrome and three cases receiving corticosteroid therapy. The mean potential duration of these patients was shorter than the normal range found in 13 patients with a clinical myopathy and normal in four cases not demonstrating any weakness. After successful treatment of their endocrine disturbance had restored normal muscle strength in five myopathic patients, the mean potential duration increased into the normal range. Since these three endocrine conditions have in common the factor of increased catabolism of body protein, the primary muscular abnormality may be a loss or change in muscle proteins.