The recent article by Leinung and colleagues [1] is of great public health importance in showing that megestrol acetate, a progestational agent, can suppress the pituitary-adrenal axis and result in secondary adrenal insufficiency. This information is not currently included in the Physicians' Desk Reference and remains largely unknown to prescribing physicians.

We describe a 52-year-old woman who was referred for possible adrenal insufficiency. She had had lumpectomy in 1988, followed by radiation therapy and chemotherapy for breast cancer. Because a bone scan suggested involvement of vertebrae T11 and L1, the patient received radiation therapy to the back in 1994. She began receiving megestrol acetate (40 mg, four times daily) 6 months before evaluation.

The patient's baseline serum cortisol level was 1 µg/dL (normal, 3 to 13 µg/dL). Thirty minutes after cosyntropin (250 µg) stimulation, her serum cortisol level increased to only 4.6 µg/dL (normal increase more than 7 µg/dL; peak value more than 18 µg/dL). A computed tomographic scan of the abdomen was normal. The patient's serum adrenocorticotropic hormone level was 9 pg/mL (normal, 9 to 52 pg/mL).

Because of a suspected secondary adrenal insufficiency, a magnetic resonance image of the pituitary and brain was obtained. The scan showed a small pituitary adenoma. After reading the article by Leinung and colleagues, however, we thought that the small pituitary tumor was probably an incidental finding and that megestrol acetate caused the secondary adrenal insufficiency. We believe our patient will probably require steroid coverage for stressful situations. Furthermore, should megestrol acetate therapy be discontinued in the future, it will be done slowly under close endocrine supervision.

Thousands of ill patients are currently receiving megestrol acetate, and their physicians must become aware of the potential life-threatening adrenal complications of this drug. We urge the Food and Drug Administration and the manufacturer of this product to send a letter to all physicians informing them of these potential complications.