Less Visceral Obesity and Better Muscle Mass Seen in Patients After Adrenal Gland Removal, Study Says

Patients with Cushing’s syndrome showed less abdominal fat and increased muscle mass, as well as reduced use of medications one year after having their adrenal glands removed, according to a new study.

The research, “Changes of computed tomography-based body composition after adrenalectomy in patients with endogenous hypercortisolism,” was published in the journal Clinical Endocrinology.

The adrenalectomies – removal of the adrenal glands – were performed between 2006 and 2017 on 134 patients (mean age 44, 105 women). Among them, 39 had Cushing’s syndrome, 57 had mild autonomous cortisol excess (MACE), and an additional 38 had nonfunctioning adrenal tumors (NFATs) — those that do not secrete hormones — and were used as controls.

The link between chronic excess cortisol levels and metabolic complications has been shown in patients with Cushing’s syndrome, as well as in those with mild autonomous cortisol excess (MACE). MACE patients also have excess cortisol in circulation but lack the typical external characteristics of those with Cushing’s.

MACE carries a significant burden, but doctors still need reliable biomarkers that help determine which patients are still at risk of metabolic complications after adrenal surgery and ensure normalization of cortisol levels.

Chronic cortisol excess can lead to an accumulation of visceral fat and progressive loss of skeletal muscle. This has been showed via computed tomography (CT) in patients with MACE or adrenal adenomas (benign tumors), suggesting that changes in CT-measured body composition may be markers for the severity of cortisol excess.

However, longitudinal changes in these parameters after surgery were only assessed in patients with adrenal incidentalomas, which are asymptomatic adrenal masses. Also, changes in skeletal muscle radiodensity (SMD), a marker inversely associated with intramuscular fat content, have rarely been analyzed in people with cortisol excess.

A research team in Korea conducted a retrospective study to assess whether the severity of cortisol excess correlates with greater improvement of several CT-based body composition parameters, including visceral fat area (VFA), skeletal muscle area (SMA), and SMD, after adrenal surgery.

The adrenalectomies were also performed on 20 patients with NFAT, the control group. Follow-up CT data were available from 27 CS patients, 28 with MACE, and 23 with NFAT.

Patients with Cushing’s were younger, predominantly female (95%), and had higher fasting glucose and total cholesterol levels that those with NFAT or MACE. Post-dexamethasone morning serum cortisol levels were significantly higher in patients with Cushing’s or MACE than those with NFAT.

At baseline, Cushing’s patients had significantly higher visceral fat, and lower scores for all skeletal muscle measures compared to both NFAT and MACE patients.

At follow-up (approximately one year after surgery), they showed significant decreases in visceral fat and increases in skeletal muscle measures compared to baseline. Those with MACE showed significant decreases in visceral and subcutaneous (under the skin) fat, and increases in SMD. Patients with NFAT had no differences in any of these parameters.

The team also found that fewer Cushing’s patients had visceral obesity after adrenalectomy — 33% at follow-up versus 81% at baseline. Loss of skeletal muscle mass (52 % to 15 %), and low SMD (81% to 56%) was also evident in fewer Cushing’s patients compared to study’s start.

In people with MACE, only the prevalence of low SMD changed significantly (50% to 32%) at follow-up. “Patients with NFAT did not show any significant changes in the prevalence of each condition after adrenalectomy,” researchers wrote.

The study’s authors cautioned that a one-year follow-up period “might not be sufficient to detect full recovery of skeletal muscle structure, particularly in individuals with MACE who had subtle decrease in muscle mass, compared to overt [Cushing’s syndrome] at baseline.”

Data further showed that, in Cushing’s patients, all metabolic indices improved and all medications for hypertension, diabetes, and abnormal amount of lipids were reduced after surgery.

Blood pressure also lowered in both NFAT and MACE patients, but only those with MACE had their number of medications for hypertension and diabetes reduced.

Higher post-dexamethasone cortisol levels at baseline correlated with greater reductions in visceral and subcutaneous fat, as well as with improvements in muscle density.

“In conclusion, the severity of cortisol excess in patients with adrenal adenoma was independently associated with greater improvements in CT-measured VFA, VSR, and SMD after adrenalectomy,” the researchers wrote.

The assessed markers “may allow more objective assessment of [surgical] treatment benefit at earlier stage,” they added, noting these results need to be validated in further studies.