Tissue Sodium in CKD Patients

Elena Qirjazi, The University of Western Ontario

Abstract

Introduction: Sodium hemostasis is altered in patients with chronic kidney disease (CKD) due to long term loading, and sodium (²³Na) can be deposited in the skin, muscle and skeleton. We measured ²³Na content in these tissues of CKD patients, using ²³Na magnetic resonance (MR) imaging.

Methods: This is a pilot cross-sectional study of CKD stage 4-5D patients and healthy controls. Subjects underwent a ²³Na MR study of their right lower leg using a multinuclear-capable 3.0-T MRI. An axial proton T1-weighted fast-low-angle-shot sequence was acquired to delineate the anatomy; followed by a ²³Na MR image obtained with a custom-made ²³Na coil and sodium-optimized pulse sequences. Concentration maps were generated using saline solutions at different ²³Na concentrations as calibration vials. Four regions of interest (ROIs) were drawn: 1) pre-tibial skin, 2) posterior leg skin, 3) tibia, and 4) soleus muscle. Baseline characteristics and blood samples were also collected.

Results: 10 controls, 12 CKD and 23 dialysis (10 peritoneal dialysis (PD) and 13 hemodialysis (HD)) subjects participated in the study. ²³Na concentration in all four tissues was significantly higher in dialysis patients compared to controls (p-value23Na of HD, PD and CKD groups. Tissue sodium levels correlated strongly with markers of mineral bone disease and inflammation. Associated factors appear to be tissue specific.

Conclusion: Dialysis patients were found to have significantly higher ²³Na level in their tissues compared to healthy controls. The effect and clinical utility of tissue ²³Na remains to be studied.