The Metabolic Clearance Rate, Blood Production, Interconversion and Transplacental Passage of Cortisol and Cortisone in Pregnancy Near Term

Abstract

Extract: A constant infusion of ¹⁴C-cortisol and ³H-cortisone for 4 hr was given to six pregnant women, at term, at the time of elective cesarean section. Radioactive and nonradioactive cortisol (F) and cortisone (E) concentrations were determined in maternal and cord plasma at the time when the concentration of the radioactive steroids had reached a plateau. Metabolic clearance rates (MCR), plasma levels of endogenous F and E, blood production rates (BP), conversion ratios (Cr), and transfer constants ([ρ]_BB values) were calculated and compared with those obtained in eight nonpregnant women, half of whom took contraceptive medication (subjects taking “the pill”) and half of whom did not (control subjects).