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Bradley Javorsky, MD, on a New Cortisol Cutoff for Adrenal Insufficiency Diagnosis


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With the goal of reducing false positives for adrenal insufficiency (AI), scientists are recommending a new, more precise diagnostic cutoff of 14-15 μg/dL of serum cortisol, rather than the current 18 μg/dL.

The new data were published in the Journal of the Endocrine Society.

Among the 110 patients evaluated in the retrospective analysis, new cortisol cutoffs after adrenocorticotropic hormone (ACTH) stimulation were identified when using several of the newer, more widely used diagnostic assays currently available, including Elecsys II (14.6 μg/dL), Access (14.8 μg/dL), and liquid chromatography-tandem mass spectrometry (LC-MS/MS) (14.5 μg/dL).

Bradley Javorsky, MD, an endocrinologist and researcher at the Medical College of Wisconsin, served as the study's first author. He recently discussed the findings with MedPage Today. The exchange has been edited for length and clarity.

What was the key knowledge gap your study was designed to address?

Javorsky: It is safe to say that most clinicians, including many endocrinologists -- not to mention practice guidelines and clinical information resources -- still regard 18 μg/dL as the cutoff for making the biochemical diagnosis of AI after ACTH stimulation testing. However, this cutoff was derived from older polyclonal immunoassays that are no longer being used in many institutions.

Newer, more specific monoclonal immunoassays and LC-MS/MS are being used instead. With these more specific assays, one might expect the cutoffs to be lower.

What was your finding?

Javorsky: After ACTH stimulation, the cutoff values for the newer, more specific cortisol assays were indeed lower at 14-15 μg/dL.

Although there was excellent correlation between the new and older assays, the results from the new assays were 22-39% lower than those found by the older and less-specific Elecsys I assay, hence the lowered threshold.

Did anything surprise you about the study results?

Javorsky: Baseline cortisol had to be very low (approximately <2 μg/dL) in order to be predictive of subnormal cortisol values. This underscores the observation that ACTH stimulation testing is not perfectly sensitive.

What are the clinical takeaways from these results?

Javorsky: To avoid false-positive ACTH stimulation testing results -- and by extension avoid over-treating patients with glucocorticoids -- clinicians should be aware of the cortisol assay used in their institution and the new cortisol cutoff when evaluating patients for adrenal insufficiency.

It should also be reinforced that careful interpretation in the context of clinical history is still essential to making the correct diagnosis. Discordant results among different assays underscore the importance of clinical judgment from an experienced physician when diagnosing AI.

What are the takeaways?

Javorsky: I think it is important that laboratories make the type of cortisol assay used in their institution easily accessible to clinicians and strongly consider posting the new cortisol cutoff after ACTH stimulation testing when reporting results.

Read the study here and expert commentary on the clinical implications here.

 

Disclosures

Javorsky reported being a consultant for Clarus Therapeutics and a research investigator for Novartis Pharmaceuticals.

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