A pilot study to evaluate the erythrocyte glycocalyx sensitivity to sodium as a marker for cellular salt sensitivity in hypertension

Supressed plasma renin in patients with primary hypertension is thought to be an indirect marker of sodium-induced volume expansion which is associated with more severe hypertension and hypertension-mediated organ damage. A novel test for erythrocyte glycocalyx sensitivity to sodium (eGCSS) has been proposed as a direct measure of sodium-induced damage on erythrocyte surfaces and a marker of sensitivity of the endothelium to salt in humans. Here we explore if eGCSS relates to plasma renin and other clinical and biochemical characteristics in a cohort of patients with primary hypertension. Hypertensive subjects (n = 85, 54% male) were characterised by blood biochemistry (including plasma renin/aldosterone), urine analysis for albumin-creatinine ratio (ACR), 24-h urine sodium/potassium excretion. eGCSS was measured using a commercially available kit. Correlations between eGCSS and clinical and biochemical characteristics were explored using Spearman's correlation coefficient and characteristics compared across tertiles of eGCSS. eGCSS was inversely correlated with renin (p < 0.05), with renin 17.72 +/- 18 mu U/l in the highest tertile of eGCSS compared to 84.27 +/- 146.5 mu U/l in the lowest (p = 0.012). eGCSS was positively correlated with ACR (p < 0.01), with ACR 7.37 +/- 15.29 vs. 1.25 +/- 1.52 g/mol for the highest vs. lowest tertiles of eGCSS (p < 0.05). eGCSS was not correlated with other clinical characteristics or biochemical measures. These results suggests that sodium retention in hypertension characterised by a low-renin state is associated with cell membrane damage reflected by eGCSS. This may contribute to the hypertension-mediated organ damage and the excess mortality associated with sodium overload and "salt sensitivity".