Context The normal cortisol response 30 or 60 min after cosyntropin (ACTH[1-24]) is considered ≥18 μg/dL (500 nmol/L). This threshold is based on older serum cortisol assays. Specific monoclonal antibody immunoassays or LC-MS/MS may have lower thresholds for a normal response. Objective To calculate serum cortisol cutoff values for ACTH stimulation testing with newer specific cortisol assays. Design Retrospective analysis of ACTH stimulation tests performed in ambulatory and hospitalized patients suspected of adrenal insufficiency (AI). Serum samples were assayed for cortisol in parallel using Elecsys I and Elecsys II immunoassays, and when volume was available, by Access immunoassay and LC-MS/MS. Results 110 patients were evaluated. Using 18 μg/dL as the cortisol cutoff after ACTH stimulation, 14.5%, 29%, 22.4%, and 32% of patients had a biochemical diagnosis of AI using the Elecsys I, Elecsys II, Access, and LC-MS/MS assays, respectively. Deming regressions of serum cortisol were used to calculate new cortisol cutoffs based on the Elecsys I cutoff of 18 μg/dL. For 30 min values, new cutoffs were 14.6 μg/dL for Elecsys II, 14.8 μg/dL for Access, and 14.5 μg/dL for LC-MS/MS. Baseline cortisol <2 μg/dL was predictive of subnormal stimulated cortisol values. Conclusions To reduce false positive ACTH stimulation testing, we recommend a new serum cortisol cutoff of 14-15 μg/dL depending on the assay used (instead of the historical value of 18 μg/dL with older polyclonal antibody assays). Clinicians should be aware of the new cutoffs for the assays available to them when evaluating patients for AI.
ObjectiveDemonstrate the safety and efficacy of a standardized intravenous etomidate infusion protocol in normalizing cortisol levels in patients with severe and life-threatening hypercortisolism.MethodsA retrospective case series of seven patients representing nine episodes of severe hypercortisolism at two large academic medical centers was conducted. Patients were included in this series if they received an etomidate infusion for the treatment of severe and life-threatening hypercortisolism. The etomidate infusion was administered via a newly developed protocol designed to safely reduce cortisol levels until more long-term medical or definitive surgical therapy could be instituted.ResultsSeven patients representing nine episodes received etomidate treatment. In eight of nine episodes of therapy, rapid control of hypercortisolemia was achieved, generally defined as a serum cortisol level of 10 to 20 µg/dL. Patients with a median baseline cortisol of 105 µg/dL (range, 32 to 245 µg/dL) achieved a median nadir serum cortisol of 15.8 µg/dL (range, 6.9 to 27 µg/dL) after a median of 38 hours (range, 26 to 134 hours).ConclusionsA standardized continuous intravenous etomidate infusion protocol is a safe and effective means of achieving a serum cortisol level of 10 to 20 µg/dL in patients with severe hypercortisolemia.
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