Salt and Water Retention Is Associated with Microinflammation and Endothelial Injury in Chronic Kidney Disease

Abstract

Multifrequency bioimpedance spectroscopy (BIS) is an established method for assessing fluid status in chronic kidney disease (CKD). However, the technique is lacking in predictive value and accuracy. BIS algorithms assume constant tissue resistivity, which may vary with changing tissue ionic sodium concentration (Na+). This may introduce significant inaccuracies to BIS outputs. To investigate this, we used 23 Na magnetic resonance imaging (MRI) to measure Na + in muscle and subcutaneous tissues of 10 healthy controls (HC) and 20 patients with CKD 5 (not on dialysis). The extracellular (Re) and intracellular (Ri) resistance, tissue capacitance, extracellular (ECW) and total body water (TBW) was measured using BIS. Tissue water content was assessed using proton density-weighted MRI with fat suppression. BIS-derived volume indices were comparable in the two groups (OH: HC-0.4±0.9L v CKD 0.5±1.9L, p=0.13). However, CKD patients had higher Na + (HC 21.2±3.0, CKD 25.3±7.4mmol/L; p=0.04) and significantly lower Re (HC 693±93.6, CKD 609±74.3Ohms; p=0.01); Ri and capacitance did not vary. Na + showed a significant inverse linear relationship to Re (rs=-0.598, p<0.01) but not Ri. This relationship of Re (y) and Na + (x) is described equation y=-7.39x+814. A 20% increase in tissue ionic Na + is likely to overestimate ECW by 1.2-2.4L. Tissue Na + concentration has a significant inverse linear relationship to Re. BIS algorithms to account for this effect could improve prediction accuracy of bioimpedance derived fluid status in CKD.

Molecular and physical technologies for monitoring fluid and electrolyte imbalance: A focus on cancer population

“…141 Furthermore, there are reports of specific biomarkers profiles, such as IL-8 and E-selectin (fluid overload) and intercellular adhesion molecules (salt distribution), that may play a significant and discriminatory role for a better understanding of fluid imbalance and other pathophysiological responses. 146 Some studies suggest salivary biomarkers, including metabolome, which could provide biochemical and genetic profiling of hydration status. The scope of new noninvasive metabolome profiles can be expanded to additional metabolites and key electrolytes whose concentrations in saliva, tear, and urine display close relationships with those in blood.…”

“…Furthermore, there are reports of specific biomarkers profiles, such as IL‐8 and E‐selectin (fluid overload) and intercellular adhesion molecules (salt distribution), that may play a significant and discriminatory role for a better understanding of fluid imbalance and other pathophysiological responses 146 . Some studies suggest salivary biomarkers, including metabolome, which could provide biochemical and genetic profiling of hydration status.…”

Assessment of Endothelial and Microvascular Function in CKD: Older and Newer Techniques, Associated Risk Factors, and Relations with Outcomes

“…In ESKD patients, E-selectin was reversely related to cardiovascular events, LVH, and total mortality, while a specified E-selectin gene polymorphism was associated with carotid atherosclerosis [127-129]. In a previous work, E-selectin and ICAM-1 were also correlated with salt and water retention in ESKD [130].…”

Body Fluid-Independent Effects of Dietary Salt Consumption in Chronic Kidney Disease

“…Furthermore, it was reported that hemodialysis in these patients resulted in a significantly lower muscle sodium content and a tendency to lower skin sodium compared with controls. In a study using 23 NaMRI to evaluate tissue sodium concentration in pre-dialysis CKD patients, it was reported that these patients had higher skin sodium concentrations, but no differences were found in sodium muscle concentrations [97]. Moreover, it was found that both salt and water accumulation in these patients was associated with the elevation of serum markers for endothelial activation and of inflammatory pathways.…”