Simultaneous quantitation of seven endogenous C-21 adrenal steroids by liquid chromatography tandem mass spectrometry in human serum.

Quantitation of endogenous steroids is important in the diagnosis of several endocrine disorders. In this study we present a new method for simultaneous quantitation of cortisol, cortisone, 11-desoxycortisol, 21-desoxycortisol, corticosterone, 17-hydroxyprogesterone and 11-desoxycorticosterone in human serum by on-line extraction and LC-MS/MS. Analytes extraction was performed on-line using a 2-position and 6-port valve equipped with a monolithic silica cartridge. After chromatographic separation of all analytes, detection was performed in the multiple reaction monitoring mode using positive atmospheric pressure chemical ionization mode. Total imprecision of the assay ranged from 5.5 to 15.5%. Comparison with immunoassays yielded coefficients of 0.893 for cortisol, 0.848 for 11-desoxycortisol and 0.924 for 17-hydroxyprogesterone. The sensitivity of this method provides meaningful data for patients within normal and elevated range and it may be useful for the diagnosis of a variety of adrenal dysfunctions.