Tissue sodium stores in peritoneal dialysis and hemodialysis patients determined by sodium-23 magnetic resonance imaging

Abstract

Background Tissue sodium content in patients on maintenance hemodialysis (MHD) and peritoneal dialysis (PD) were previously explored using 23Sodium magnetic resonance imaging (23NaMRI). Larger studies would provide a better understanding of sodium stores in patients on dialysis as well as the factors influencing this sodium accumulation. Methods In this cross-sectional study, we quantified the calf muscle and skin sodium content in 162 subjects (10 PD, 33 MHD patients, and 119 controls) using 23NaMRI. Plasma levels of interleukin-6 (IL-6) and high-sensitivity C-reactive protein (hsCRP) were measured to assess systemic inflammation. Sixty-four subjects had repeat 23NaMRI scans that were analyzed to assess the repeatability of the 23NaMRI measurements. Results Patients on MHD and PD exhibited significantly higher muscle and skin sodium accumulation compared to controls. African American patients on dialysis exhibited greater muscle and skin sodium content compared to non-African Americans. Multivariable analysis showed that older age was associated with both higher muscle and skin sodium. Male sex was also associated with increased skin sodium deposition. Greater ultrafiltration was associated with lower skin sodium in patients on PD (Spearman’s rho=-0.68, P = 0.035). Higher plasma IL-6 and hsCRP levels correlated with increased muscle and skin sodium content in the overall study population. Patients with higher baseline tissue sodium content exhibited greater variability in tissue sodium stores on repeat measurements. Conclusions Our findings highlight greater muscle and skin sodium content in dialysis patients compared to controls without kidney disease. Tissue sodium deposition and systemic inflammation seen in dialysis patients might influence one another bidirectionally.

Reduction of Tissue Na+ Accumulation After Renal Transplantation

“…Previous 23 Na-MRI investigations revealed a gender-dependence and age-correlation of tissue Na + storage. 7,10 Indeed, we have also found these correlations in our cohort pre and post transplantation. Furthermore, 2 out of 31 CKD patients were diagnosed with type 2 diabetes mellitus, a condition known to enhance tissue Na + accumulation in HD patients.…”

“…Thus, results should not be generalized to all ethnicities, which is important as for instance African Americans are known to accumulate higher amounts of tissue Na + . 10 The pathophysiological implications of tissue Na + storage have to be further elucidated.…”

“…9 Tissue Na + accumulation occurs in maintenance hemodialysis (HD) and peritoneal dialysis patients. 10 HD patients with type 2 diabetes mellitus -who are at a particularly high risk for CVD -have higher tissue Na + content compared to non-diabetic HD patients. 11 Removal of tissue Na + in HD patients during a regular 4-hour dialysis treatment is independent of dialysis ultrafiltration, whereas the concentration of vascular endothelial growth factor-C (VEGF-C), a lymphatic growth factor, correlates with skin Na + mobilization in these patients.…”

Animal, Human, and 23Na MRI Imaging Evidence for the Negative Impact of High Dietary Salt in Children

“…Preliminary observations from our group point out that children may have the lowest tissue sodium concentration [ 66 •], as opposed to adult dialysis patients where tissue sodium concentrations are largest [ 67 , 68 ]. Though intuitively increased dietary sodium intake should be associated with increased tissue sodium levels, clinical evidence in this respect is scarce; Bracconier et al have shown that in healthy individuals, higher salt intake is associated with higher sodium concentrations in muscle tissue and sweat [ 69 •].…”

Total Body Sodium Balance in Chronic Kidney Disease

“…Studies visualising the sodium tissue signal with 23 Na MRI have demonstrated that tissue sodium is correlated with age [ 24 , 59 , 71 – 73 ] and male gender [ 24 , 71 – 74 ] in healthy controls as well as those with CKD. In CKD, tissue sodium concentrations increase progressively across the spectrum [ 74 ].…”