Peter Linz
Erlangen University Hospital, Germany
Title: 23Na magnetic resonance imaging of sodium removal in hemodialysis patients
Biography
Biography: Peter Linz
Abstract
Sodium is stored in skin and muscle tissue. The amounts stored in hemodialysis (HD) patients are unknown. We hypothesized that 23Na magnetic resonance imaging (Na-MRI) could allow assessing tissue Na+ and its removal. We studied 24 HD patients, and 27 age-matched healthy controls. We also investigated 20 HD patients before and shortly after HD with a batch dialysis system, permitting direct measurements of Na+ in dialysate and ultrafiltrate. Age was associated with higher tissue Na+ content in controls and this increase was paralleled by an age-dependent decrease of circulating levels of vascular endothelial growth factor-C (VEGF-C). Older (>60 years) HD patients showed increased Na+ and water in skin and muscle. HD patients showed lower VEGF-C levels than age-matched controls. After HD treatment, patients with low VEGF-C levels had higher skin Na+ content than patients with high VEGF-C levels (low VEGF-C: 2.30.3 ng/ml and skin Na+: 24.38.2 mmol/L; high VEGF-C: 4.11.0 ng/ml and skin Na+: 18.25.8 mmol/L; P<0.05). We conclude that Na-MRI quantitatively detects Na+ stored in skin and muscle in humans and allows studying Na+ storage reduction in ESRD patients. Age and VEGF-C-related local tissue-specific clearance mechanisms may determine the efficacy of tissue Na+ removal with HD. Prospective trials on the relationship between tissue Na+ content and hard endpoints could provide new insights into Na+ homeostasis, and clarify whether increased Na+ storage is a cardiovascular risk factor.