Metabolic Acidosis in Patients with Chronic Kidney Disease: Diagnosis, Pathogenesis, and Treatment-A Narrative Review

Metabolic acidosis is a common complication of chronic kidney disease (CKD). The kidneys play a crucial role in acid-base balance, maintaining pH within the normal range (isohydria) by following mechanisms: bicarbonate reabsorption, ammogenesis, and titratable acidity. The anion gap describes the amount of unmeasured anions and is classically evaluated as the difference between the major cation (sodium) and the sum of the two major anions (chloride and bicarbonate). Metabolic acidosis can be divided into two types: normal anion gap metabolic acidosis and high anion gap metabolic acidosis. A high anion gap level is considered unfavorable in terms of prognosis as it is associated with increased mortality. Treatment of metabolic acidosis in patients with chronic kidney disease, despite available therapeutic options, is a challenge. Supplementation with bicarbonates does not improve prognosis on the one hand, and on the other hand, it may be harmful. The new KDIGO guidelines for 2024 have been significantly modified compared to 2012 after negative results of studies on bicarbonate supplementation. Bicarbonate supplementation is currently recommended only when levels are less than 18 mmol/L. This review provides an overview of the current knowledge on the pathophysiology, classification, and therapeutic options, including dietary recommendations and new pharmacology agents.