After several months of dexamethasone treatment, a patient with a glioblastoma shows abdominal symptoms. What is the most likely cause of these symptoms?

The abdominal symptoms experienced by a patient undergoing prolonged dexamethasone treatment for glioblastoma are most likely attributed to adrenal insufficiency. Dexamethasone is a potent corticosteroid that, when used over an extended period, can lead to suppression of the hypothalamic-pituitary-adrenal (HPA) axis. This suppression results in a reduced production of endogenous glucocorticoids by the adrenal glands.

In a healthy individual, the body maintains homeostasis through the regulation of cortisol levels, particularly in response to stress. When exogenous corticosteroids like dexamethasone are administered, the feedback mechanism can lead to adrenal atrophy and decreased endogenous cortisol levels. If the dexamethasone is abruptly discontinued or if the body requires more cortisol than is available due to the suppressed adrenal function, symptoms of adrenal insufficiency can manifest. These may include weakness, fatigue, abdominal pain, nausea, and, in severe cases, an adrenal crisis, which can lead to further complications.

Understanding this mechanism is crucial, especially in patients receiving long-term steroid therapy, as symptoms of adrenal insufficiency can sometimes be mistaken for other conditions, including side effects of the medication itself or complications from their underlying disease. Therefore, monitoring and potentially