The largest study of benign adrenal tumors has just been completed. Results have been published in the Annals of Internal Medicine. Specifically, this study examined the effect of mild autonomous cortisol secretion (MACS) from the benign adrenal tumors. It uncovered that MACS leads to a risk of type 2 diabetes and hypertension (high blood pressure), particularly in women.

Therefore, all individuals who are diagnosed with a benign adrenal tumor need to be tested for MACS, and should have their glucose levels and blood pressure monitored regularly.

The Study 

This study included 1300 individuals (median age of 60) who had recently been diagnosed with benign adrenal tumors (more than 1cm).

The study found that MACS is much more common than thought previously. MACS is defined in patients without clinical features of Cushing syndrome (CS) as a “failure to suppress morning serum cortisol concentration less than 50 nmol/L” after a previous treatment of dexamethasone (1mg orally). About half of the patients in this study had normal suppression of cortisol and nonfunctioning adrenal tumors. 35% had moderate cortisol levels and a possibility of MACS. 11% had a definitive MACS diagnosis due to high cortisol levels. Finally, 5% had overt CS, despite the efforts to exclude this patient population from the study originally.

Additionally, the researchers found a relationship between cortisol production and sex. Women made up 64% of those who had nonfunctioning adrenal tumors, 74% with definitive MACS, and 86% of patients with CS. 

When studying the incidence of hypertension and diabetes, it was found that-

• Patients who had definitive MACS were 15% more likely to face hypertension.
• Patients who had overt CS were 37% more likely to face hypertension 
• The more excess cortisol a patient had, the more likely they were to need 3 or more drugs to treat hypertension.
• Patients who had overt CS were 62% more likely to be diagnosed with type 2 diabetes. There was not a significant association for those with MACS.
• Those with MACS and overt CS and a diagnosis of type 2 diabetes were more likely to need insulin.

These data show that patients with MACS have a similar cardio metabolic burden as those with CS. This is true even when they don’t have the typical excess cortisol.

You can read more about this study and what the findings mean here.