Isolated adrenocorticotropic hormone deficiency development during chemotherapy for gastric cancer: a case report

INTRODUCTION: Isolated adrenocorticotropic hormone deficiency is an endocrinological disorder characterized by loss of adrenocorticotropic hormone and resultant adrenal insufficiency. Affected patients often present with fatigue, anorexia, and hyponatremia. Although the number of reported cases has been recently increasing, isolated adrenocorticotropic hormone deficiency combined with malignant neoplasia is very rare. Here we describe a patient with gastric cancer who developed unexpected isolated adrenocorticotropic hormone deficiency during chemotherapy. CASE PRESENTATION: A 72-year-old Japanese man was admitted to our hospital because of febrile neutropenia due to chemotherapy for gastric cancer recurrence. Although the neutropenia and fever immediately improved, he became unable to take any oral medications and was bedridden 1 week after admission. His serum sodium level abruptly decreased to 122mEq/L on the fifth day of hospitalization. We performed endocrinological studies to investigate the cause of his hyponatremia and plasma hyposmolality. His plasma adrenocorticotropic hormone and cortisol levels were very low. However, his serum levels of all other anterior pituitary hormones were slightly elevated. We then performed a corticotropin-releasing hormone test, which showed that neither his plasma adrenocorticotropic hormone nor cortisol level responded to corticotropin-releasing hormone stimulation. We definitively diagnosed isolated adrenocorticotropic hormone deficiency based on these findings. Hydrocortisone replacement therapy was begun at 20mg/day, resulting in a marked improvement in his anorexia and general fatigue within a few days. His serum sodium level was also normalized immediately after the administration of hydrocortisone. He was discharged from our hospital on the 50th day of hospitalization. CONCLUSIONS: The present case is the second report of a patient with concurrent isolated adrenocorticotropic hormone deficiency and gastric cancer and the first report of a patient diagnosed with isolated adrenocorticotropic hormone deficiency during the course of chemotherapy for a solid malignant neoplasm. Although the symptoms and signs described in the present report are common observations during chemotherapy, it is important to consider not only the adverse effects of antineoplastic agents, but also isolated adrenocorticotropic hormone deficiency as a differential diagnosis. Hydrocortisone replacement therapy for isolated adrenocorticotropic hormone deficiency effectively avoids the unnecessary cessation of chemotherapy.