Abstract: Multiple myeloma is common in the older population and is treated mainly with chemotherapy. However, chemotherapy-related side effects imitate the clinical manifestations of Sheehan's syndrome, which leads to misdiagnosis and missed diagnosis, particularly for older patients without a clear history of postpartum hemorrhage. Therefore, when older women with malignant myelomas show refractory hyponatremia and gastrointestinal disorders while under chemotherapy, a diagnosis of Sheehan's syndrome should be considered. The early detection of the disorder will guarantee timely individualized treatment.