Effects of pediatric chronic kidney disease and its etiology on tissue sodium concentration: a pilot study

Background Sodium-23 magnetic resonance imaging ( 23 Na MRI) allows non-invasive assessment of tissue sodium concentration ([Na + ]). Age and chronic kidney disease (CKD) are associated with increased tissue [Na + ] in adults, but limited information is available pertaining to children and adolescents. We hypothesized that pediatric CKD is associated with altered tissue [Na + ] compared to healthy controls. Methods This was a case–control exploratory study on healthy children and adults and pediatric CKD patients. Study participants underwent an investigational visit, blood/urine biochemistry, and leg 23 Na MRI for tissue [Na + ] quantification (whole leg, skin, soleus muscle). CKD was stratified by etiology and patients’ tissue [Na + ] was compared against healthy controls by computing individual Z-scores. An absolute Z-score > 1.96 was deemed to deviate significantly from the mean of healthy controls. Pearson correlation was used to compute the associations between tissue [Na + ] and kidney function. Results A total of 36 pediatric participants (17 healthy, 19 CKD) and 19 healthy adults completed the study. Healthy adults had significantly higher tissue [Na + ] compared with pediatric groups; conversely, no significant differences were found between healthy children/adolescents and CKD patients. Four patients with glomerular disease and one kidney transplant recipient due to atypical hemolytic-uremic syndrome had elevated whole-leg [Na + ] Z-scores. Reduced whole-leg [Na + ] Z-scores were found in two patients with tubular disorders (Fanconi syndrome, proximal–distal renal tubular acidosis). All tissue [Na + ] measures were significantly associated with proteinuria and hypoalbuminemia. Conclusions Depending on etiology, pediatric CKD was associated with either increased (glomerular disease) or reduced (tubular disorders) tissue [Na + ] compared with healthy controls. Graphical abstract A higher resolution version of the Graphical abstract is available as Supplementary information .