Ultrastructural abnormalities in muscular vessels of hyperthyroid patients.

An electron microscope study of needle biopsies from the quadriceps muscle was carried out in 11 non-selected patients (ten females and one male), with clinically and laboratory-diagnosed hyperthyroid disease. Alterations of the normal structure of muscle fibres were found in all cases. Changes in capillaries were found in ten patients, and ranged from an increase in basement membrane thickness with reduplication, to total destruction of the capillaries. The importance of the vascular involvement in the muscles of patients with Graves-Basedow disease is stressed.