with fever, hypotension, and lethargy. She was diagnosed with urinary tract infection and treated with piperacillin and tazobactam. While in the hospital, she was started on MA 400 mg/d for anorexia and weight loss. After improvement with antibiotics and hydration, she was discharged back to the nursing home, where she was noted to be alert with a blood pressure of 121/80 mmHg but appeared generally weak with a voice just above an audible whisper.One month after MA was started, her systolic blood pressure had gradually decreased to the 80s, and she remained alert, but her generalized weakness and anorexia had worsened, and she became bedbound, being unable to stand or walk without assistance. Her blood chemistry was significant for sodium of 133 mmol/L (normal range 135-142 mmol/L) but was otherwise unremarkable, including thyroid function test. Morning cortisol (3.1 lg/dL, normal range 6.0-22.4 lg/dL) and adrenocorticotropic hormone (ACTH) were low (<5 pg/mL, normal range 5-27 pg/mL). MA-related AI was suspected. Dexamethasone 0.5 mg twice a day was started for clinical response because dexamethasone would not affect cosyntropin stimulation test. MA was tapered and discontinued. Cosyntropin stimulation test revealed a blunted adrenal response to intramuscular cosyntropin 250 lg with cortisol levels of 2.8 lg/dL at 0 minutes, 7.7 lg/dL at 30 minutes, and 13.1 lg/dL at 60 minutes. Brain magnetic resonance imaging did not show tumor.She made remarkable improvements. Her appetite significantly improved, her blood pressure normalized, and her soft voice resolved. Her general weakness also improved to the point where she could ambulate short distances with a walker. More importantly, she regained a great measure of her quality of life, to the point that she was able to go on outings with her family.This case illustrates the importance of keeping AI in the differential diagnosis in cases in which an elderly adult presents with a constellation of symptoms of which each symptom individually, such as generalized weakness, can suggest a myriad of differential diagnoses. In addition, in cases in which an individual is taking MA, the risk of AI should be kept in mind. With a wider recognition of the side effects of MA and awareness that it is on the Beers criteria for potentially inappropriate medications for older adults, MA should be used judiciously, weighing the risks and benefits. 2 MA is a synthetic progestational agent that has been used for breast and endometrial cancer and as an appetite stimulant for anorexia and cachexia. 3 AI can be categorized into primary and secondary AI. 4 In this case, AI was secondary, caused by MA-induced suppression of ACTH secretion, which in turn caused decreased cortisol production. MA is known to have glucocorticoid-like activity, which can suppress the hypothalamic-pituitaryadrenal axis. 5 Doses as low as 160 mg/d can suppress ACTH secretion. 6 Uncorrected or untreated, AI can lead to death. The presentation of AI can be nonspecific, increasing the risk of delayed diagnosis or misdia...