Clinical applications of LC-MS sex steroid assays: Evolution of methodologies in the 21st century

Purpose of review: The purpose of this review is to summarize why and how liquid chromatography tandem mass spectrometry (LC-MS/MS) is increasingly replacing other methodologies for the measurement of sex steroids. Recent findings: Measurement of sex steroids, particularly testosterone and estradiol, is important for diagnosis or management of a host of conditions (e.g. disorders of puberty, hypogonadism, polycystic ovary syndrome, amenorrhea, and tumors of ovary, testes, breast and prostate). Historically, metabolites of testosterone and estradiol were measured as ketosteroids in urine using colorimetric assays that lacked sensitivity and specificity due to endogenous and exogenous interferences. Extracted competitive manual radio-immunoassays provided improved, but still imperfect, specificity, and offered increased sensitivity. As testing demand increased, they were displaced by automated immunoassays. These offered better throughput and precision, but suffered worse specificity problems. Moreover, agreement between different immunoassays has often been poor and they are all compromised by a limited dynamic measurement range. To overcome these problems, LC-MS/MS methods have been developed and validated for quantitation of sex steroids. These methods reduce interferences, provide better specificity, improve dynamic range, and reduce between-method bias. Summary: Endocrine Society and Urology Society guidelines have highlighted the limitations of the immunoassays for sex steroids and have provided convincing evidence that mass spectrometric methods are preferable for measurement of sex steroid hormones. In this review, we describe LC-MS/MS methods for measurement of testosterone and estradiol.