We report four patients with primary hypothyroidism (3 female, aged 47
, 46, 49 and 34 years old) whose principal manifestation was muscle in
volvement. The diagnosis was oriented by the finding of myoedema and a
slow relaxation phase of tendon reflexes. In one patient, an electrom
yographic and histological study was performed. Thyroid substitution l
ead to an improvement in myopathy in all patients.