ABSTRACT
This chapter includes 17-oxosteroids, methods for measuring cortisol and its metabolites, and aldosterone. The indications for aldosterone assays are so few, and the methods are so expensive, that it is likely that most hospital laboratories will send specimens away. For many years the assay of 17-oxosteroids in urine was the only direct way of measuring adrenal cortical steroid production which was routinely available for clinical use. Certainly the 17-oxosteroid excretion as measured is always greater, sometimes considerably so, than the sum of the known 17-oxosteroids measured separately by specific methods, but the reasons for the differences are not defined. Deterioration of the borohydride will lead to high values of control urines because preexisting 17-oxosteroids will be measured those formed from the 17-oxogenic steroids. Unconjugated steroids are extracted from plasma or urine with dichloromethane. The concentration of cortisol in the extract is determined by measuring the displacement of cortisol from a limited number of binding sites on corticosteroid binding globulin.
