“…Most of the methods in wide use are based on the Porter-Silber reaction which is moderately specific for the 17,21-dihydroxy-20 keto-side chain, and therefore should detect cortisol, cortisone and compound S in an organic-solvent-extractable (Le., free, nonconjugated) state. For practical purposes cortisol is probably the only steroid measured under usual condi tions (492). Normal values have ranged from 3 to 28 ",g. per cent (323, 335, 493 to 499) .…”