Quantification of urinary 3α,21-dihydroxy-5β-pregnan-20-one and 5-pregnene-3β, 20α-diol by mass fragmentography

A sensitive and accurate method is described for measuring urinary corticosteroids by gas chromatography-mass spectroscopy (GC-MS). Using single peak monitoring (mass fragmentography) and electron impact ionization, the acetates of 3α,21-dihydroxy-5β-pregnan-20-one (tetrahydrodeoxycorticoster-one) and 5-pregnene-3β,20α-diol were estimated with deuterio-acetate carriers as recovery markers. With this technique, the coefficient of variation did not exceed 3% for GC-MS analyses of the urinary corticosteroid samples by single peak monitoring. An evaluation of the trimethylsilyl ether derivatives of the two steroids by chemical ionization was also made. Secretion rates determined for deoxycorticos-terone derived from specific activities of urinary tetrahydrodeoxycorticosterone and excretion levels of 5-pregnene-3β,20α-diol were slightly lower than those obtained by other methods.