Synthesis of [2H8] estradiol, [2H7] estrone, [2H6] 2-hydroxyestrone and [2H6] 4-hydroxyestrone as internal standards for selected ion monitoring

The art of measuring steroids: Principles and practice of current hormonal steroid analysis

Steroids are small and highly important structural or signalling molecules in living organisms and their metabolism is complex. Due to the multiplicity of enzymes involved there are many different steroid related disorders. E.g., an individual enzyme defect is rather rare but can share various clinical symptoms and can thus be hardly diagnosed clinically. Therefore, reliable hormonal determination still presents the most reasonable initial diagnostic approach and helps to avoid uncritical and expensive attempts at molecular diagnostic testing. It also presents a backbone of monitoring these complex patients. In science, reliable hormone measurement is indispensable for the elucidation of new mechanisms of steroid hormone actions. Steroid analytics is highly challenging and should never be considered trivial. Most common methods for steroid determination comprise traditionally immunoassay, or more recently, mass spectrometry based methods. It is absolutely necessary that clinicians and scientists know the methods they are applying by heart. With the introduction of automated direct assays, a loss of quality could be observed over the last two decades in the field of steroid immunoassays. This review wants to meet the need for profound information and orientation in the field of steroid analysis. The pros and cons of the most important methods, such as immunoassays and mass spectrometry based methods will be discussed. The focus of the latter will lie on gas chromatography-mass spectrometry (GC-MS) as well as liquid chromatography-mass spectrometry (LC-MS). Selected analytical applications from our Deutsche Forschungsgemeinschaft Research Group FOR 1369 "Sulfated Steroids in Reproduction" will illustrate the contents. In brief, immunoassays have for long presented the traditional technique for steroid analysis. They are easy to set up. Only one analyte can be measured per immunoassay. Specificity problems can arise and caution has to be exerted especially regarding direct assays lacking purification steps. Mass spectrometry based methods provide structural information on the analyte and thus higher specificity. In combination with chromatographic techniques, they permit the simultaneous determination of a multitude of analytes. Highest specificity can be obtained using GC-MS, a sophisticated but most powerful tool for characterizing steroid metabolomes. LC-MS is a true high throughput technique and highly suited for detecting complex steroids. GC-MS and LC-MS are not competing but complementary techniques. Since reliable steroid determination requires extremely high expertise in the field of analytics as well as steroid biochemistry, it is recommended that collaborations and networking with highly specialized centers of expertise are developed.

Determination of catechol and guaiacol estrogens in urine by capillary gas chromatography/mass spectrometry

A gas chromatographic (GC)/mass spectrometric method for the simultaneous determination in urine of 2- and 4-hydroxyestrones and hydroxyestradiols, and their monomethyl ethers, is described. Separation of these catechol and guaiacol estrogens was achieved by derivatization into their trimethylsilyl and tert-butyldimethylsilyl ethers, followed by capillary GC on a DB-1 column. The calibration graphs were satisfactorily constructed for these estrogen metabolites by selected ion monitoring at the respective molecular ions using 2-bromoestrone and 4-hydroxyestradiol-d3 3-methyl ether as internal standards. The extraction and purification of the desired estrogens in biological fluids were effected by the combined use of Extrelut-3 and ion exchange columns. The sensitivity and reliability obtained by the newly developed method has proved to be satisfactory for the quantitation of catechol and guaiacol estrogens in human urine.

Synthetic procedures for the preparation of deuterium-labeled analogs of naturally occurring steroids

The object of this article is to review the procedures that have been published concerning the preparation of deuterium-labeled analogs of naturally occurring steroid hormones. In combination with mass spectrometric methods, these stable isotope-labeled compounds should be applicable for human metabolism studies or as internal standards. Deuteration techniques for the elucidation of stereochemical problems, procedures for the preparation of monodeuterated steroids, and synthesis of deuterated analogs of nonbiologic steroids have therefore not been included in this review.

A gas chromatographic/mass spectrometric assay for catechol estrogens in microsomal incubations: comparison with a radiometric assay

A gas chromatographic/mass spectrometric assay for quantifying two catechol estrogens, 2-hydroxyestradiol and 4-hydroxyestradiol, in microsomal preparations is described. The assay employs deuterium-labeled analogs of the catechol estrogens as internal standards and permits quantification of catechol estrogens, in microsomal incubations, at low (1-2) microM concentrations. The compounds are analyzed as their trimethylsilyl derivatives following separation by capillary gas chromatography.

Estrogen 2-, 4-, 6- or 16-hydroxylation by human follicles shown by gas chromatography-mass spectrometry associated with stable isotope dilution

Follicular fluid, obtained by aspiration of human Graafian follicles in cycles stimulated by clomiphene and hMG + hCG, was analyzed for estrogen content. Carefully controlled extraction and efficient preliminary chromatographic separations were set up. Deuterium labelled analogues were used as internal standards for the quantitative determination by gas chromatography-mass spectrometry and some new derivatives were included in the identification procedure. The identified estrogens and their mean concentrations (ng/ml) are: 2-hydroxy-estrone (0.14), 4-hydroxy-estrone (0.12), 2-hydroxy-estradiol (0.36), 4-hydroxy-estradiol (0.34), 6 alpha-hydroxy-estradiol (13.2), 6 beta-hydroxy-estradiol (6.40), 2-methoxy-estrone (0.83), 2-methoxy-estradiol (10.5), 16-oxo-estradiol (0.41), estriol (10.2), estradiol-17 beta (1365), estradiol-17 alpha (1.91), estrone (211). Metabolism of estradiol by 6-hydroxylation seems to be predominant in the human ovary. The other data suggest that 2-hydroxylation, with subsequent O-methylation, and 16-hydroxylation may be by equivalent pathways, since the sum of the 2-methoxy-estrone and 2-methoxy estradiol concentrations is rather similar to the estriol concentration. Hence, the latter three compounds and the 6-hydroxy-estradiols may be end-products of follicular estrogen metabolism. Catechol estrogen formation by 2-hydroxylation and 4-hydroxylation is shown to be of equal importance in the ovary. These results confirm the presence in the human follicle of various competing estrogen hydroxylases and catechol-O-methyltransferase.