Total Visceral Area but Not Visceral Fat Is Higher in Primary Aldosteronism

Presentation Number: SUN 526
Date of Presentation: April 2nd, 2017

Aya T. Nanba*1, Adina F. Turcu2, Brian A. Derstine3, Christopher S Lee3, Brian Ross3, June A. Sullivan3, Stewart C. Wang3 and Elif A Oral1
1University of Michigan, Ann Arbor, MI, 2The University of Michigan, Ann Arbor, MI, 3University of Michigan

Abstract

Background: Primary aldosteronism (PA) is associated with a higher prevalence of metabolic syndrome, alterations in glucose homeostasis and higher cardiovascular risk. A correlation between plasma aldosterone concentrations and BMI has been reported in patients with essential hypertension, but not in PA. Furthermore, the alterations of body composition associated with excessive aldosterone remain controversial.

Objective: To dissect the body composition of patients with PA.

Methods: We studied 23 patients (13 men, median age 56 years, median BMI 31) with PA and 23 sex-, age-, and BMI-matched controls, selected from patients scanned for trauma. Hormonal data and adrenal vein sampling (AVS) results were reviewed for the PA group. We performed analytic morphomics on abdominal CT images from all patients. The fascial envelope and skin outline were automatically defined using key points within the linea alba, dorsal muscles groups, and paraspinus lateral seams at specified vertebra points. The following measurements were analyzed: the distance from the inferior-anterior aspect of the L1 vertebral body to fascia (VF); the distance from fascia to front skin (FS); the distance between the posterior tip of the spine and back skin (SS); cross-sectional area inside fascia (FA); visceral fat area (VA), defined as the area within the FA meeting fat density thresholds; and subcutaneous fat area (SA). The non-parametric Mann-Whitney U test was used to compare the two groups.

Results: In the PA group, the median plasma aldosterone concentration (PAC), plasma renin activity (PRA) and PAC/PRA ratio (ARR) were 31 ng/dL, 0.2 ng/mL/hr and 134, respectively. All but three patients had hypokalemia. Unilateral PA was diagnosed in 11 patients (48%, 5 women). PAC was higher in unilateral than in bilateral PA (38.2 ng/dL vs. 20.6 ng/dL, p=0.018), while PRA and ARR were no different between the two subtypes. The VF and FA were significantly greater in patients with PA than in controls (median VF, 145 mm in PA vs. 130 mm in controls, p=0.02; median FA, 644 cm2 in PA vs. 627 cm2 in controls, p<0.05). VA, FS, SS and SA were not significantly different between the two groups. The relative proportion of visceral fat, defined as VA/(VA+SA), was significantly higher in women with PA than in controls (32 in PA vs. 26 in control, p=0.002), but no difference was observed in men. Interestingly, the relative proportion of visceral fat correlated negatively with PAC in women (r=-0.6, p=0.0006), while no correlation was observed in men.

Conclusion: These preliminary results suggest that PA leads to mixed body composition alterations, which differ between sexes. We speculate that the visceral adiposity is not the main determinant of the increased prevalence of metabolic syndrome in PA.

 

Nothing to Disclose: ATN, AFT, BAD, CSL, BR, JAS, SCW, EAO