Postdialysis serum phosphate equilibrium in hemodialysis patients on a controlled diet and no binders

• Published in: Hemodialysis international Vol. 26; no. 2; pp. 255 - 263
• Main Authors: Stremke, Elizabeth R., Trevino, Laurie, Doshi, Simit, Moorthi, Ranjani N., Hill Gallant, Kathleen M., Moe, Sharon M.
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01.04.2022
• Subjects: Diet; hemodialysis; Humans; Kidney Failure, Chronic; Phosphates; Phosphorus; Renal Dialysis - methods; hemodialysis; diet; phosphorus
• ISSN: 1492-7535; 1542-4758; 1542-4758
• DOI: 10.1111/hdi.12999

Background Studies evaluating the change in serum phosphate post hemodialysis (HD) demonstrate an initial decline during dialysis but a rebound post dialysis. However, previous studies were done on usual diet and phosphate binders, with limited number of blood draws, confounding conclusions. We determined serum phosphate reduction, rebound, and equilibrium over 48 h in HD patients consuming a controlled, low phosphorus diet without binders. Methods Serum phosphate (mg/dL) was analyzed before and after a HD treatment and frequently during the ensuing 48 h intradialytic period in the clinical research unit. Thirteen subjects were enrolled and had been off phosphate binders for 10 days and consumed a standardized low phosphate (900 mg/day) diet for 3 weeks prior to the assessments. Linear regression was used to determine relationships between the pre‐HD serum phosphate, decline post‐HD (post‐HD drop); and a 48 h area under curve (AUC) using the trapezoidal method as a measure of overall phosphate levels from the end of dialysis to 48 h post dialysis. Repeated Measures ANOVA with Dunnett's posthoc test was used to determine rebound. Results Five of 13 subjects returned to >90% of their pre‐HD serum phosphate within the first 24 h post‐HD, and serum phosphate was 94 ± 0.11% (range 63%–113%) by 48 h after the completion of HD. The 48 h AUC of serum phosphate during the interdialytic period was correlated with both pre dialysis phosphorus (r = 0.85; p = 0.0002) and the pre‐post drop in serum phosphate during dialysis (r = 0.69; p = 0.0085). In contrast, the net ultrafiltration was not related to the 48 h AUC of serum phosphorus (r = 0.20; p = 0.51). Conclusions In hemodialysis patients on standard low phosphorus diet and no phosphate binders, the interdialytic serum phosphorus level, assessed as AUC, is determined by the pre dialysis phosphorus and net‐change in serum phosphorus during the dialysis treatment, but not the ultrafiltration volume [Correction added on 25 January, after first online publication: In the last sentence of the , the word “potassium” has been replaced with “phosphorus” to improve accuracy.].