A GAS-CHROMATOGRAPHIC METHOD FOR THE DETERMINATION OF NEUTRAL STEROID PROFILES IN URINE, INCLUDING STUDIES ON THE EFFECT OF OXYTETRACYCLINE ADMINISTRATION ON THESE PROFILES IN MEN

A capillary gas chromatographic method for the determination of 'total' metabolic profiles of urinary neutral steroids was developed. The method is based on anion exchange chromatographic separation and purification of monoglucuronide-, monosulphate- and double-conjugated neutral steroids on DEAE-Sephadex A-25 microcolumns and the final analysis of the individual steroids in these conjugate groups is carried out by capillary column gas-liquid chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The method was shown to provide a convenient and accurate determination of total metabolic profiles of neutral steroids in urine and thus, can be used for metabolic studies of steroids and for diagnostic purposes. In the present investigation the effect of a tetracycline antibiotic on the production and metabolism of neutral steroids in men was studied during a 5-day oral administration of oxytetracycline. The results showed that the influence of oxytetracycline on neutral steroids was minor and mainly restricted to the changes in urinary neutral steroid glucuronide excretion. Oxytetracycline decreased the mean daily excretion of total neutral steroid monoglucuronides by 20% and a statistically significant decrease was found in the urinary excretion of 3-alpha-hydroxy-5-beta-androstan-17-one-glucuronide (etiocholanolone, 31%, P < 0.05), 5-beta-pregnan-3-alpha,20-alpha-diol-glucuronide (pregnanediol, 32%, P < 0.05) and corticosteroid glucuronides, including 3-alpha,11-beta,17-alpha,20-beta,21-pentahydroxy-5-beta-pregnan- and 3-alpha,17-alpha,20-beta,21-tetrahydroxy-5-beta-pregnan-11-one-glucuronides (beta-cortol and beta-cortolone, 36%, P < 0.05). The reason for this effect is unknown, but may be partly due to inhibition of intestinal hydrolysis of biliary steroid conjugates, which previously was shown to result in an interruption of enterohepatic circulation of steroids and an increased excretion of steroid conjugates by the faecal route.