Metabolic acidosis in hemodialysis patients: a review

Abstract

Metabolic acidosis is highly prevalent in hemodialysis patients. The disorder is associated with increased mortality and its deleterious effects are already present in the predialysis phase of chronic kidney disease. Metabolic acidosis has been linked to progression of chronic kidney disease, changes in protein and glucose metabolism, bone and muscle disorders and cardiovascular disease. At present, the control of metabolic acidosis in hemodialysis is mainly focused on the supply of bicarbonate during dialysis session, but further studies are needed to set the optimum target serum bicarbonate and the best concentration of the bicarbonate dialysate. The present study reviews pathophysiological and epidemiological aspects of metabolic acidosis in hemodialysis patients and also addresses its adverse effects and treatment.

Understanding Development of Malnutrition in Hemodialysis Patients: A Narrative Review

“…Metabolic acidosis develops in the early stages of CKD from the kidney’s inability to excrete nonvolatile acids and synthesize bicarbonate to maintain acid–base balance [ 122 ]. HD treatment aims to correct metabolic acidosis via bicarbonate concentration of the dialysate [ 123 ], ultrafiltration rate [ 124 ], dialyzer membrane surface area and permeability [ 125 ], blood and dialysis flow rate [ 124 ], transmembrane concentration gradient set by the patient’s serum bicarbonate level and bicarbonate availability from the dialysate [ 125 ], and dialysis adequacy [ 122 , 123 ] through maintaining the pre-dialysis serum bicarbonate levels between 24 and 26 mmol/L as recommended by current opinion [ 126 ]. However, metabolic acidosis correction depends on patient-related determinants such as interdialytic weight gain [ 123 ], acid generation from high protein intake [ 122 , 127 ], or gastrointestinal losses of bicarbonate [ 122 , 125 ].…”

“…However, metabolic acidosis correction depends on patient-related determinants such as interdialytic weight gain [ 123 ], acid generation from high protein intake [ 122 , 127 ], or gastrointestinal losses of bicarbonate [ 122 , 125 ]. Individual fluctuation in patients’ bicarbonate levels challenges optimum management [ 122 ].…”

“…Metabolic acidosis contributes to malnutrition by reducing protein synthesis and increasing muscle degradation [ 123 ]. The malnutrition pathway in HD patients involves protein catabolism, secondary insulin resistance, inflammation, and increased serum leptin levels [ 122 ]. Lines of evidence using animal and human studies explain that increased muscle breakdown occurs during metabolic acidosis via two mechanisms.…”

“…Additionally, the acidic environment affects insulin binding to receptors, thus reducing tissue sensitivity to insulin and affecting glucose uptake [ 131 ]. Separately, metabolic acidosis also inhibits the anabolic effect of insulin, causing muscle depletion in dialysis patients [ 122 ]. Moreover, cell culture studies have shown that TNF-α and interleukins are generated in an acidic environment, triggering an inflammatory response [ 132 , 133 ].…”

The Effect of Acidosis on Albumin Level in Patients Treated With Regular Hemodialysis (Single Center Study)

“…-Increases in the pH of the medium even above normal physiologic pH, were associated with progressively higher rates of protein synthesis (Rezende, Brandão de Souza, Modesto Pereira, & Lugon, 2017).…”