[Useful and pointless steroid determinations: appropriate laboratory diagnosis of adrenal cortex function].

A generation ago, the determination of urinary 17-hydroxycorticoids was the best available laboratory procedure for assessing adrenocortical function. Today, the plasma cortisol concentration, measured by radioimmunoassay, is a much more specific and reliable parameter, particularly in combination with simple functional tests, which are also suitable for ambulatory patients. The most appropriate tests of adrenocortical function for the diagnosis or exclusion of Cushing's syndrome or of primary and secondary adrenocortical failure are briefly described. Substitution therapy in patients with adrenocortical insufficiency must be evaluated by clinical criteria and not by steroid analysis.