Steroid hormone conjugates secretion

Steroid hormones are generally converted into inactive metaboic excretion products in the liver. Reactions include reduction of unsaturated bonds and the introduction of additional hydroxyl groups. The) resulting structures are made more soluble by conjugation with curonic acid or sulfate (from PAPS, see p. 160). Approximate ) twenty to thirty percent of these metabolites are secreted into the bile and then excreted in the feces, whereas the remainder ae t released into the blood and filtered from the plasma in the kidney, passing into the urine. These conjugated metabolites are fairb1 water-soluble and do not need protein carriers. 

However new questions were asked Are other steroid conjugates secreted How and where are these secreted products biosynthesized and metabolized Are the sulfo conjugates biologically active, and what is their role in hormonal regulation Only a few of these questions can be answered yet. 

According to the classical view of metabolism the hormones are synthesized as free steroids in endocrine tissues and prepared for excretion in urine by peripheral metabolism and conjugation. This view had to be modified upon the isolation of dehydroepiandrosterone sulfate from adrenal tumor [307]. Thus dehydroepiandrosterone sulfate, a steroid conjugate, was shown to be secreted by the adrenal tissue. Isotopic methods also pointed in the same direction. Lieberman et al. [304], using... 

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