SKIN NA+, K+ AND WATER BEFORE AND AFTER SURGICAL CURE OF HUMAN PRIMARY ALDOSTERONISM

Abstract

Objective: Excess salt (sodium) intake is strongly associated with arterial hypertension (HT) in Primary aldosteronism (PA), the prototype of salt-dependent HT, which can be surgically cured with laparoscopic adrenalectomy. As recent evidences pointed to skin Na+ content as a key component of body sodium content, we investigated the effects of surgical cure of PA with adrenalectomy on the skin amount of Na+, K+, water and of Tonicity Enhancing Binding Protein (TonEBP), a transcription factor promoting neolymphoangiogenesis in the skin. Design and Methods: We obtained skin biopsies in 35 consenting PA patients (40% women, age 56 ± 10 yrs) before and 1 month after surgical cure of PA patients with adrenalectomy. Na+, K+, and water content were measured by chemical-physical methods and TonEBP mRNA copy number by digital droplet PCR. Results: We found that the biopsies dry weight was higher in specimen obtained at surgery compared to those collected afterwards (p < 0.001) and showed a tight direct correlation with Na+, K+, and water content (all p < 0.01). After adjustment for specimen dry weight, skin K+ (1.14 ± 0.1 μg/mg before vs 2.81 ± 0.27 μg/mg after surgery, p < 0.001) and water content (2.92 ± 1.4 mg/mg before vs 3.85 ± 0.23 mg/mg after surgery, p < 0.001) increases after surgery, while skin Na+ content showed no changes. Increased Na+ and water drainage due to enhanced TonEBP mRNA copy number in PA could explain this unexpected observation. Conclusion: A sizable cohort of surgically cured PA patients showed that PA is associated with skin K+ depletion which is corrected after surgical cure. At variance we found no evidence for a surgically correctable increased tissue Na+ content in PA patients. The prominent increase in the skin expression of the TonEBP mRNA, suggesting enhanced tissue Na+ and water drainage via enhanced lymphoangiogenesis in PA patients, can explain this lack of overt Na+ skin accumulation.