[A case of isolated ACTH deficiency accompanied by generalized painful muscle cramp]

We report a patient who had generalized painful muscle cramps associated with isolated ACTH deficiency. A 68-year-old woman was hospitalized because of painful muscle cramps present for one year. Neurological examination revealed no abnormalities except for generalized painful muscle cramps. Serum electrolyte and CPK levels were normal. Serum ACTH and cortisol levels as well as urine 17-OHCS were low. An ACTH loading test employing insulin, TRH and LH-RH indicated isolated ACTH deficiency. Just after the muscle cramp, EMG revealed a low amplitude in the biceps muscle. Colon biopsy showed mild fibrosis and inflammatory cell infiltration in the lamina propria. Her muscle cramps improved markedly after two weeks of hydrocortisone replacement therapy and resolved after three weeks, suggesting that this symptom was closely related to isolated ACTH deficiency. Our case suggests that isolated ACTH deficiency may present with very similar clinical symptoms to Satoyoshi disease.