Ammonium bicarbonate powder

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.

Abstract licence: CC BY

Acid-base homeostasis is maintained by renal and respiratory systems. The inability of the renal tubules to excrete acids or retain bicarbonate in adequate amounts leads to renal tubular acidosis (RTA). These disorders are characterised by the presence of normal anion gap metabolic acidosis with hyperchloremia. Both distal RTA (type 1) and proximal RTA (type 2) can occur due to a primary/inherited defect in the renal tubule or may arise due to some secondary/acquired causes. Urinary acidification defect defines type 1 RTA, while type 2 RTA is characterised by defective bicarbonate handling in the proximal tubule. Type 3 RTA includes features of both type 1 and type 2 RTA, whereas type 4 RTA is characterised by the presence of hyperkalaemia with normal anion gap metabolic acidosis. In this review article, we describe the various types of RTA and its pathophysiology along with a systematic and practical approach to a suspected case of RTA and its management.

Abstract licence: CC BY-NC-SA