title: Radioimmunoassay of 18-hydroxy-11-deoxycorticosterone in plasma.
abstract: A method is described for the radioimmunoassay of 18-OH-DOC using antibodies generated in rabbits against the carboxymethoxime derivative coupled to bovine serum albumin. The procedure uses 4 ml of plasma with intra and interassay variations of 8 and 9% respectively. Standard 18-OH-DOC added to plasma from an adrenalectomized patient gave a regression equation, Y=0.974X+/-2.210 and a correlation coefficient of 0.999. The only cross reacting steroid, 18-OH-B which may lead to falsely high levels is removed by a single thin layer chromatographic step. Blood levels in normal subjects agree closely with those calculated indirectly by metabolic clearance and secretion rate measurements. ACTH stimulation produced an 18-fold increase in plasma concentration while dexamethasone suppression decreased levels 3-fold. Four hours in the upright position resulted in a decreased plasma concentration while aldosterone increased. No significant response to dietary sodium restriction could be demonstrated.
mesh_terms: D015070:18-Hydroxydesoxycorticosterone / Q000097:blood* / Q000276:immunology; D000324:Adrenocorticotropic Hormone; D000450:Aldosterone / Q000097:blood; D000704:Analysis of Variance; D000818:Animals; D002940:Circadian Rhythm; D003900:Desoxycorticosterone / Q000031:analogs & derivatives*; D003907:Dexamethasone; D005260:Female; D006801:Humans; D008297:Male; D011187:Posture; D011817:Rabbits / Q000276:immunology; D011863:Radioimmunoassay / Q000379:methods
chemical_list: D015070:18-Hydroxydesoxycorticosterone; D003900:Desoxycorticosterone; D000450:Aldosterone; D003907:Dexamethasone; D000324:Adrenocorticotropic Hormone