The effect of the pituitary-adrenal axis on epinephrine synthesis in the human adrenal medulla was examined by the estimation of the 24-h urinary epinephrine level after treatment with glucocorticoids in four patients with systemic lupus erythematodes (SLE), one patient with rheumatoid arthritis (RA) and one patient with adrenal pheochromocytoma. 24-h urinary catecholamines (CAs) were measured by HPLC before and after glucocorticoid treatment, dexamethasone or predonisolone was orally given for more than seven days to patients with SLE, RA or isloated ACTH deficiency and five days to a patient with adrenal pheochromocytoma.
In patients with isolated ACTH deficiency, the 24-h urinary epinephrine level was significantly lower than the normal range. In patients with SLE or RA, the 24-h urinany epinephrine level was normal and it was significantly suppressed by therapeutic doses of prednisolone 30-40mg/day. In a patient with adrenal pheochromocytoma, 24-h urinary epinephrine was extremely high and it was significantly increased after dexamethasone 0.5mg/day.
These results suggest that epinephrine synthesis in the human adrenal medulla may be dependent on the pituitary-adrenal axis. But the increase in epinephrine synthesis due to dexamethasone in a patient with pheochromocytoma may reflect the direct effect via the feeding artery to the tumor, as previously shown in an in vitro culture system.