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BACKGROUND: New high-performance liquid chromatography/ tandem mass spectrometry (LC-MS/MS) methods are among the most successful approaches to improve specificity problems inherent in many immunoassays.
CONTENT: We emphasize problems with immunoassays for the measurement of steroids and review the emerging role of LC-MS/MS in the measurement of clinically relevant steroids. The latest generation of tandem mass spectrometers has superior limits of quantification, permitting omission of previously employed derivatization steps. The measurement of steroid profiles in the diagnosis and treatment of congenital adrenal hyperplasia, adrenal insufficiency, chronic pelvic pain and prostatitis, oncology (breast cancer), and athletes has important new applications.
CONCLUSIONS: LC-MS/MS now affords the specificity, imprecision, and limits of quantification necessary for the reliable measurement of steroids in human fluids, enhancing diagnostic capabilities, particularly when steroid profiles are available.
© 2009 American Association for Clinical Chemistry
Steroid hormones are synthesized from cholesterol, and many are of great clinical importance (1). Synthesis occurs in the mitochondria and smooth endoplasmic reticulum of cells in the adrenal cortex, the gonads, and the placenta (Fig. 1). The adrenal gland is composed of the adrenal medulla and cortex. The latter is divided into 3 anatomic zones: the zona glomerulosa, which produces the mineralocorticoids such as corticosterone and aldosterone, and the zonae fasciculata and reticularis, which together produce the glucocorticoids (11-deoxycortisol, cortisol) and the adrenal androgens [dehydroepiandrostenedione (DHEA),5 DHEA-sulfate (DHEAS)], which in the adrenals are produced in far higher amounts than androstenedione and testosterone. Aromatase [cytochrome P (CYP)- 450 19, CYP19A1] adds 2 double bonds to ring A of testosterone, yielding estradiol with an aromatic ring A, and it also aromatizes ring A of androstenedione to form estrone (E1).
One of the goals in the treatment of some breast cancers is reduction of estrogen concentrations. This can be achieved through the use of aromatase inhibitors (AIs), which block the conversion of androgens to estrogens (2). AIs do not sufficiently block estrogen synthesis by the ovaries, however, but do block other tissues from converting androgens to estrogens. For this reason, AIs are used mostly in women who have reached menopause, when the ovaries no longer synthesize steroids. E1 synthesized mainly by aromatase conversion of androstenedione is metabolized to several steroid metabolites, including CYP1A2 conversion to 2-hydroxyestrone (2-OHE1) and CYP3A4 and CYP1A2 to...