Studies on Phenolic Steroids in Human Subjects. XXI. Renal Metabolism, Conjugation and Excretion of Four Androgens: A Comparison with Estriol

Abstract

The present study was conducted in order to ascertain whether the human kidney can conjugate androgens to an extent similar to that of estriol (E3). Differently labeled androgens (testosterone, DHT and androstenedione) were injected simultaneously into a peripheral vein and the renal artery. The excretion of the radioactivity in the early urine collections served as an index of the ability of the kidney to conjugate and/or metabolize the various steroids administered. It was shown that the human kidney can conjugate testosterone to some extent as the 17-glucuronide of DHT, but to a much lesser degree that E3. Androstenedione was not conjugated by the kidney and the excretion DHT was paradoxically lower following its renal artery administration than following its peripheral injection. We interpret the latter to indicate that some kidney cells may contain receptors with very high affinity for DHT, thus leading to the lower excretion observed. The administration of androstenediol (into the renal artery) and E3 (peripherally) indicated that the diol was not conjugated as readily as E3. The results point to the ability of the kidney to conjugate testosterone to some extent; however, in no case was it able to conjugate an androgen with the same facility as it does E3.