Assessment of Endocrine Function

Abstract The first step in the laboratory assessment of endocrine function is usually to determine if hormone production is within the normal range. The ability to measure hormone concentrations accurately in plasma, urine, and saliva has allowed us to define normal endocrine function and to diagnose abnormalities in hormone production. Perhaps the single most important advance in modern endocrinology has been the development of immunoassays to measure the small quantities of hormones that circulate in the blood. Static hormone measurements, however, may not provide conclusive evidence of dysfunction in a given endocrine system. Therefore, dynamic or provocative endocrine tests have been developed to stimulate or suppress production of a particular hormone. As our understanding of the role of receptors in mediating hormone action has grown, assays that assess target tissue responsiveness to hormones have been developed. Advances in chromatographic and analytical chemistry techniques have also allowed more precise measurements of some hormones for which good immunoassays have not yet been developed. This chapter describes the various methods for quantifying hormone concentrations and thus assessing endocrine function.