Association of predialysis serum sodium level with fluid status in patients on maintenance hemodialysis

Purpose The ability to maintain sodium and water homeostasis is impaired in patients with end-stage renal disease (ESRD), leading to hyponatremia and fluid overload. The aim of this study was to evaluate the association between serum sodium level and body fluid status in patients on maintenance hemodialysis (HD). Methods This was a prospective observational study on patients with ESRD and who were on maintenance HD between June and November 2018. Assessment of body fluid status using bioimpedance spectroscopy and measurement of serum sodium level were conducted simultaneously predialysis. The association of fluid status with predialysis sodium level was analyzed. Results Sixty-two patients were enrolled in the study group. Compared with patients with predialysis normonatremia, those with predialysis hyponatremia had higher levels of blood urea nitrogen, serum potassium, phosphate, normalized protein catabolic rate, and interdialytic weight gain (IDWG) (p < 0.05). The correlations of predialysis sodium level with chronic fluid status, such as fluid overload, were not significant. Logistic regression analysis found significant association of IDWG with predialysis hyponatremia. Conclusion Predialysis hyponatremia was associated with increased IDWG. The substantial variation in serum sodium levels, regardless of fluid status, indicated the complex relationship between sodium and water balance in patients on maintenance HD.