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

G. Emons, G. R. Merriam, D. Pfeiffer, D. L. Loriaux, P. Ball, R. Knuppen

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38 Scopus citations


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 μg/h) or 2-OHE2 (100 μg/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.

Original languageEnglish (US)
Pages (from-to)499-504
Number of pages6
JournalJournal of Steroid Biochemistry
Issue number5
StatePublished - Nov 1987
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology


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