FLUORIMETRIC DETERMINATION OF FREE PLASMA 11-HYDROXYCORTICOSTEROIDS IN MAN

Abstract

ABSTRACT A fluorimetric method for the determination of the free 11-hydroxycorticosteroids (cortisol and corticosterone) in human plasma has been described. Using a routine fluorimeter, 1–2 ml plasma samples are needed for a valid determination. The procedure is reliable as judged by the criteria of Borth (1957). One single trained technician can perform 40–50 determinations a day. Background fluorescence equivalent to about 3 μg % hydrocortisone is found; this background fluorescence does not appear to be related to plasma cholesterol. The method is designed primarily to study the dynamics of adrenocortical function in a given individual and can be of help as an emergency screening test (a determination can be done in one hour) in cases of suspected adrenocortical dysfunction.