Urine free-cortisol determination. A useful tool in the management of chronic hypoadrenal states.

The clinical value of urine free-cortisol (UFC) determination in the management of hypoadrenal states in patients receiving maintenance glucocorticoid therapy was assessed. Nine patients with primary adrenal insufficiency collected five 24-hour urine specimens while taking their usual oral dose of cortisone acetate or hydrocortisone. Each urine sample was assayed for UFC and creatinine. The range of UFC level for the group was from 9.4 to 43 micrograms/24 hr (10 to 21 micrograms/g of creatinine). However, for each patient the amount of UFC showed little day-to-day variation, with the coefficient of variation ranging from 8% to 26%. The UFC values of the patients with hypoadrenalism who were receiving treatment were well within the values of UFC in the control population (n = 523). Four cases illustrating the usefulness of UFC determination in patients receiving an oral maintenance regimen of hydrocortisone or cortisone are presented. The UFC is a useful biochemical marker that correlated clinically with glucocorticoid deficiency or excess in patients with hypoadrenalism receiving maintenance steroid replacement.