Plasma conjugated androgens in a dialysis-dependent male as immunoreactive digitalis-like factors

Endogenous digitalis-like factors (DLF) including those which were immunoreactive with digoxin antibody and those which displaced ouabain from Na,K-ATPase, were isolated from the plasma of a dialysis-dependent male patient not taking digoxin. Plasma was passed through a C18 disposable column, the DLF eluted with methanol and separated by HPLC on a C8 column. Immunoreactive DLF were measured in each 1 ml HPLC fraction using radioimmunoassay (RIA) for digoxin. The immunoreactive peaks were determined and aliquots from each peak analyzed by fast atom bombardment mass spectroscopy (FAB-ms). The compounds in the five major HPLC immunoreactive peaks were identified as: 1) dehydroepiandrosterone glucuronide and tetrahydrocortisone glucuronide; 2) epiandrosterone glucuronide; 3) dehydroepiandrosterone sulfate and androsterone glucuronide; 4) epiandrosterone sulfate and 5) androsterone sulfate and androstanediol glucuronide. These immunoreactive DLF represent 70% of the total plasma immunoreactive DLF of 0.124 micrograms digoxin equivalents/l. Aliquots of the HPLC fractions were also assayed for ability to displace ouabain from Na,K-ATPase. The ouabain displacing DLF gave a very different elution pattern from that obtained by RIA with the major Na,K-ATPase ouabain displacing DLF eluting in the more polar fractions. They remain unidentified.