Applications of a modified Cortipac procedure for the estimation of urinary free cortisol in various clinical situations.

A modification of the Cortipac procedure (Radiochemical Centre, Amersham) for the estimation of urinary free cortisol was found to be of value in the diagnosis of Cushing's syndrome and in the differentiation of simple obesity from that due to Cushing's syndrome. The effect of renal failure and late pregnancy on the urinary free cortisol was also studied. The results were expressed both in terms of the urinary free cortisol and as a urinary free cortisol:creatinine ratio.