Metabolism of exogenous 4- and 2-hydroxyestradiol in the human male

J Steroid Biochem. 1987 Nov;28(5):499-504. doi: 10.1016/0022-4731(87)90508-5.


The metabolic fate of the isomeric catecholestrogens 4-hydroxyestradiol (4-OHE2) and 2-hydroxyestradiol (2-OHE2) was studied to elucidate possible differences in their metabolism as an explanation for their different bioactivities. Healthy young men (n = 3 each) were infused (90 min) with 4-OHE2 (60 micrograms/h) or 2-OHE2 (100 micrograms/h). The main metabolites were determined in plasma and urine before, during and after infusion. Unconjugated and conjugated steroids, the latter after hot acid hydrolysis, were subjected to chromatography on LH-20 columns and measured by specific RIAs. During the infusion 4-OHE2 reached significant plasma concentrations whereas 2-OHE2 was so rapidly metabolised that its plasma levels remained virtually undetectable in spite of a higher infusion rate. The metabolism of 4-OHE2 was dominated by direct conjugation, that of 2-OHE2 by methyl ether formation. These findings were corroborated by the urinary excretion rates: during the infusion and the first hours afterwards, 4-OHE2 was mainly excreted as 4-OHE2 and 4-hydroxyestrone, while 2-OHE2 was predominantly excreted as 2-hydroxyestradiol 2-methyl ether and 2-hydroxyestrone 2-methyl ether.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Estradiol / analogs & derivatives*
  • Estradiol / metabolism
  • Estradiol / pharmacokinetics
  • Estrogens, Catechol / metabolism*
  • Humans
  • Kinetics
  • Male
  • Structure-Activity Relationship


  • Estrogens, Catechol
  • Estradiol
  • 2-hydroxyestradiol
  • 4-hydroxyestradiol