COMPARISON OF PLASMA ANDROGEN GLUCURONIDE LEVELS AFTER PERCUTANEOUS OR PERORAL ANDROGEN TREATMENT IN MEN - EVIDENCE FOR IMPORTANT SPLANCHNIC CONTRIBUTION TO PLASMA 17-BETA-HYDROXYANDROGEN GLUCURONIDES

To investigate whether glucuronides of 17beta-hydroxyandrogens are formed mainly in peripheral tissues or in splanchnic tissues, we compared androstanediol (AD) glucuronide (ADG) and dihydrotestosterone (DHT) glucuronide (DHTG) levels as well as the ratios of glucuronides over free steroids after transcutaneous DHT gel administration to levels and ratios found after oral administration of testosterone undecanoate. Whereas DHT and AD plasma levels were much higher after transcutaneous DHT gel administration, ADG and DHTG levels as well as glucuronide/free androgen ratios were an order of a magnitude higher after oral TU. This indicates that 17beta-hydroxyandrogen glucuronides cannot be considered specific metabolites of androgen target tissues and are formed to a large extent in the splanchnic circulation.