SAT-002 Measurement of Visceral Fat Using Computed Tomography in Two Subtypes of Primary Aldosteronism

Context: A strong association between excess visceral fat and the presence of metabolic factors, hypertension and type 2 diabetes have been demonstrated. Patients with primary aldosteronism (PA) are complicated by metabolic syndrome more frequently than those without PA. Aldosterone-induced mineralocorticoid receptor activation has been reported to impair insulin sensitivity in adipocytes and skeletal muscle. An excess of visceral fat has been hypothesized to cause an elevation of aldosterone secretion, and to cause insulin resistance in patients with PA. Objectives: To clarify the role of visceral fat in the pathophysiology of PA, we investigated the correlation of visceral fat parameters with plasma aldosterone concentration (PAC), and the correlation of visceral fat parameters with homeostasis model assessment insulin resistance (HOMA-R) in patients with PA. Materials and methods: This retrospective observational study comprised 131 patients diagnosed with PA between 2007 and 2017 at Sapporo City General Hospital. We divided participants into two subtypes, aldosterone producing adenoma (APA, n = 47) and idiopathic hyperaldosteronism (IHA, n = 84), utilizing adrenal venous sampling. We excluded patients with suspected autonomous cortisol secretion, defined as serum cortisol levels ≧ 3 μg/dL after a 1-mg dexamethasone suppression test. We analyzed the correlations of visceral fat percentage (VF%), visceral fat area (VFA) evaluated by computed tomography studies and PAC, and the correlations of VF% and VFA with HOMA-R in each subtype group. Results: Age and sex distribution was not different between patients with APA and patients with IHA (p = 0.85, p = 0.18, respectively). PAC was significantly higher in patients with APA than patients with IHA (p < 0.001). Serum potassium levels were significantly lower in patients with APA than patients with IHA (p < 0.001). Body mass index was not different between these two subtypes (p = 0.87). VF% was significantly higher in patients with IHA than in those with APA (p = 0.02). The number of patients treated as type 2 diabetes mellitus with oral medicine, HbA1c, and HOMA-R were not different between these two subtypes (p =0.76, p =0.22, p = 0.12, respectively). Patients with IHA showed a positive correlation of VF% with PAC (r = 0.377, p < 0.001), and VFA with PAC (r = 0.443, p < 0.001). In contrast, patients with APA showed no significant correlation of VF% and VFA with PAC. Patients with APA and patients with IHA showed a positive correlation of VF% and VFA with HOMA-R. Conclusions: Between two subtypes of PA, the association of visceral fat on insulin resistance was not different. The association of visceral fat on PAC was different in two subtypes of PA. Only in patients with IHA, visceral fat may play a role in regulation of aldosterone secretion.