HORMONE CONCENTRATIONS TO ASSESS ADRENAL FUNCTION IN CRITICALLY ILL PATIENTS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Activation of the pituitary adrenal function during stressful events is a major physiological defense mechanism marked by elevated adrenocorticotropic hormone (ACTH) production and increased glucocorticoid secretion. Currently used measures to assess the integrity of the adrenal function rely on serum cortisol determinations. With the high degree of protein binding for cortisol in the circulation, its serum concentration is changed with alterations in these binding proteins. A recent study demonstrated that serum free cortisol levels are better markers for glucocorticoid secretion. This study will investigate the value of measuring salivary cortisol concentration as a marker for serum free cortisol level in critically ill adult patients. It will also study the value of measuring ACTH-dependent adrenal androgens (DHEA/DHEA-S) as markers for adrenal function in this population. The hypothesis is that salivary cortisol concentration strongly correlates with the serum free cortisol level and that such measurements would be a reliable and practical surrogate for glucocorticoid secretion in critically ill patients. This would be particularly important in patients with hypoproteinemia where measured total serum levels can be misleadingly low. The study will enroll 38 adult men and women in the intensive care unit and 19 healthy volunteers of similar age and gender distribution (a total of 57 subjects). Subjects will have a clinical assessment by the endocrine team to determine eligibility for study. Subjects will have one standard cortrosyn stimulation test involving blood and saliva collection. For all normal volunteers, this test will be conducted in an outpatient visit at the GCRC. The endocrine team will provide a written clinical evaluation of all patients involved in the study, including diagnostic and therapeutic recommendations pertinent to each patient's endocrine clinical assessment. The data obtained from this protocol will serve as a pilot study for a larger multi-center investigation evaluating these measures to define illness-specific adrenal responses.