Isolated Adrenocorticotropin Deficiency Concomitant with Graves' Disease: A Case Report and Literature Review

A 73-year-old Japanese woman with untreated Graves' hyperthyroidism developed glucocorticoid-induced adrenal insufficiency (AI) after a supraphysiological dose of prednisolone therapy for bronchial asthma. Days later, she had high plasma adrenocorticotropic hormone (ACTH) levels and was expected to recover from glucocorticoid-induced AI. Her plasma ACTH levels remained high over 3 months during a physiological dose of hydrocortisone replacement. However, she suffered a further decrease in her serum cortisol level and was diagnosed with isolated adrenocorticotropin deficiency (IAD), in which bioinactive ACTH likely caused the high ACTH value. IAD should be considered as an unusual disorder associated with Graves' disease, especially in older patients.