Since estrone sulfate (E1S) is present at high concentration in plasma, we have examined the parameters of the plasma estrone, estradiol, E1S system. The metabolic clearance rate of E1S was 157 liter/day (range 70-292) in men and women. Estimated plasma production rates of E1S were (μgrams per day): men, 77; women, early follicular phase, 95; women, early luteal phase, 182. The conversion of plasma estrone and estradiol to E1S was measured and from these data and the metabolic clearance rates of the estrogens, the transfer factors were ρE1E1S = 0.54 and ρE2E1S = 0.65. Using average production rates, all plasma E1S could be shown to be derived from plasma estrone and estradiol.
