Mild Cortisol Excess Increases Mortality in Adrenal Incidentaloma

Miriam E. Tucker

May 24, 2021

Mortality is two to three times higher in patients with adrenal incidentalomas who have autonomous cortisol secretion levels of 83 nmol/L (3 µg/dL) or more after a 1 mg dexamethasone suppression test (DST) compared with those with levels below this, new research finds.

Autonomous cortisol secretion (ACS) has been linked to hypertension, cardiovascular disease, type 2 diabetes, and early mortality, and risks vary by cortisol level.

"To adequately decide whether treatment should be surgery or medical management of possible complications, it is essential to know the risk associated with the actual level of ACS," write Albin Kjellbom, MD, of Skåne University Hospital, Lund, Sweden, and colleagues, in their article published today in Annals of Internal Medicine.

Asked to comment, Salila Kurra, MD, of the Columbia Adrenal Center, Columbia University Irving Medical Center, New York City, told Medscape Medical News, "This idea that mild cortisol excess that doesn't meet the threshold for overt Cushing's can, in and of itself, cause increased morbidity and mortality is something people have been thinking about for many years now."

"But there isn't very clear guidance on exactly what to do in that situation, whether the incidentaloma should be removed, medically managed, or the patient should just be watched...It may be clinically significant, but the way to sort that out is to do other testing."   

Most Deaths Were From Cardiovascular Disease or Cancer

Adrenal lesions are found incidentally in approximately 2% to 7% of the adult population who undergo abdominal imaging, and up to a third of those have ACS in the absence of clinical signs of Cushing syndrome.

European guidelines state that a plasma cortisol level of 138 nmol/L (5 µg/dL) or greater following DST defines ACS and a level less than 50 nmol/L (1.8 µg/dL) rules it out, while values 50-137 (1.8-5 µg/dL) are deemed "possible" ACS.

For their study, the authors retrospectively analyzed 1048 consecutive patients with adrenal incidentalomas seen at two Swedish hospitals between 2005 and September 2015 who were followed for up to 14 years.

The patients were a median age of 64.9 years, and 58.5% were women.

At baseline, 45.1% had a cortisol level of 50 nmol/L (1.8 µg/dL) or higher following DST, 52.9% had hypertension, 18.7% had diabetes, and 20.6% had a medical history of one or more cardiovascular events. A total of 54 patients underwent adrenalectomy, eight of them more than 2 years after the DST.

Researchers found a linear increase in mortality risk with increasing cortisol values up to 200 nmol/L (7.25 µg/dL) following DST.

Over 14 years, 16.2% (170 patients) died. Compared with cortisol less than 50 nmol/L (1.8 µg/dL) following DST, adjusted hazard ratios for mortality were 2.30 and 3.04 for cortisol levels 83 to 137 nmol/L (3-5 µg/dL) and 138 nmol/L (5 µg/dL) or greater, respectively, and both were significant.

Among the patients who died, causes of death were cardiovascular disease in 38%, cancer in 30%, infection in 4%, and other diseases in 28%.

Patients with post-DST cortisol levels of 83 nmol/L (3 µg/dL) or higher had increased cardiovascular mortality, while those with levels of 50-82 nmol/L (1.8-3.0 µg/dL) did not. In contrast, mortality rates from cancer, infection, and other diseases didn't vary across groups.

Implications: Further Testing, Prospective Studies Needed

"The increase in mortality associated with cortisol DST values of 83 nmol/L or higher has implications," the authors say.

"We suggest [medical] treatment of known cardiovascular risk factors in these patients and incorporation of our results in the decision about which patients to recommend for adrenalectomy."

In contrast, ACS with lower cortisol [< 83 nmol/L or 3 µg/dL]" following DST "is not associated with clinically relevant increased mortality within 5 to 10 years," they observe.

Kurra said she would perform further testing for any patient with an adrenal incidentaloma and a cortisol level 50-137 nmol/L (1.8-5 µg/dL) following DST, specifically, a dehydroepiandrosterone sulfate (DHEAS) test.

"If DHEAS is low and the patient has metabolic complications then I will work them up more, with adrenocorticotropin (ACTH) and 24-hour urine and go down that path of looking for the extent of overproduction of cortisol." 

She recommended an algorithm published in 2017 of an age- and sex-adjusted DHEAS ratio that provides a sensitive and specific screening test for subclinical hypercortisolism in patients with adrenal incidentalomas.

In further analyses by Kjellbom and colleagues into incidentaloma size, bilateralism, basal ACTH less than 2.0 pmol/L, or DHEAS less than 1.04 mmol/L, only DHEAS significantly predicted mortality.

"This should be studied further, specific to sex, age, and [post-DST]-cortisol strata," Kjellbom and colleagues say.

In conclusion, Kurra said the new data "confirm something that people have postulated. But because it's a retrospective review, we need prospective studies. It is an interesting finding that needs further study before we can change clinical practice."

The study was funded by unrestricted grants from the Lisa and Johan Grönberg Foundation and the Gyllenstiernska Krapperup Foundation. Kjellbom and Kurra have reported no relevant financial relationships.

Ann Intern Med. Published online May 24, 2021. Abstract

Miriam E. Tucker is a freelance journalist based in the Washington, DC, area. She is a regular contributor to Medscape, with other work appearing in the Washington Post, NPR's Shots blog, and Diabetes Forecast magazine. She is on Twitter: @MiriamETucker.

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