Conjugates of Adrenal Corticoids in Human Plasma.

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Abstract
A method is described for the determination of conjugated corticoids in human plasma, based on the extraction of the "free" corticoid (Porter-Silber chromogens) according to the method of Nelson and Samuels and the subsequent treatment of the residual plasma with 1000 U/ml of beef liver beta glucuronidase after adjustment of the pH to 4.5 with acetate buffer. The treated plasma was incubated at 37[degree] for 24 hours and following incubation dialyzed at room temperature for 48 hours against 12 volumes of 10% methanol in water. The dialysate was extracted 3 times with 1/3 volume of chloroform. The chloroform extract was exapor-ated, chromatographed, and otherwise treated in the same manner as the free fraction. The quantity of corticosteroid present was determined with phenylhydrazine in dilute H2SO4 (Porter- Silber chromagens). Further characterization of the conjugated fraction by various chemical methods and chromatography on paper according to Bush indicated tetrahydro F as the major component of this moiety in a pool of normal plasma, and after the administration of compound F to a normal subject. Under normal conditions the quantity of conjugated corticoid is approximately equal to the free. Under some circumstances, such as in Cushing''s syndrome, the conjugates may exceed the free fraction. Stress, ACTH, or the administration of compounds E or F lead to elevations in the conjugated as well as the free fractions. The rate of disappearance of the free fraction is in part related to conjugation. The rate of conjugation of corticoids in human plasma was found to be defective in subjects with liver disease.

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