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The clinical features of adrenal
insufficiency or excess are discussed in Chapters 534 and 535, respectively. The diagnostic
evaluation of adrenal function is primarily dependent on laboratory
measurements that determine the circulating levels of various steroids
and hormones, often following perturbations of the system that help
localize pathology. Clinical symptoms and signs generally lack sensitivity
or specificity, and imaging studies are rarely helpful.
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Measurement
of Plasma Concentrations of Cortisol and Other Steroids
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Measurement of the plasma concentrations of cortisol and other
circulating steroids screens for adrenal disorders and may provide
clues regarding specific enzymatic deficiencies. Tables 532-1 and 532-2 summarize the normal
plasma concentrations for a variety of steroids. With the notable
exception of dehydroepiandrosterone sulfate (DHEAS), most adrenal
steroids exhibit a diurnal variation based on the diurnal rhythm
of corticotropin (ACTH). Because the stress of illness or hospitalization
can increase adrenal steroid secretion and because diurnal rhythms
may not be well established prior to 3 years of age, it is best
to obtain two or more samples for the measurement of any steroid.1-5
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