Hyperchloremic Acidosis

Link to article at PubMed

2021 Aug 14. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan–.


Normal physiological pH is 7.35 to 7.45. A decline in pH below this range is called acidosis, an increase in this range is known as alkalosis. Hyperchloremic acidosis is a disease state where acidosis (pH less than 7.35) develops with an increase in ionic chloride. Understanding the physiological pH buffering system is important. The major pH buffer system in the human body is the bicarbonate/carbon dioxide (HCO3/CO2) chemical equilibrium system.


  1. H + HCO3 <-- --> H2CO3 <-- --> CO2 + H2O

HCO3 acts as an alkalotic substance, while CO2 functions as an acid. Therefore, an increase in HCO3 or a decrease in CO2 will make blood more alkalotic. In contrast, a decrease in HCO3 or an increase in CO2 will shift the acid-base balance towards acidic. The pulmonary system regulates CO2 levels through respiration; However, the HCO3 levels are regulated through the renal system with the help of reabsorption. Therefore, hyperchloremic metabolic acidosis is a decline in HCO3 levels in the blood.

Related Testing

When a metabolic acidosis is suspected, it is crucial to calculate the anion gap. This is defined as:

  1. Serum anion gap = (Na) - [(HCO3 + Cl)]

Where Na is plasma sodium concentration, HCO3 is plasma bicarbonate concentration, and Cl represents plasma chloride concentration.

The anion gap is an estimation to determine the quantity of ionically active components within the blood that are not routinely measured. Since there are always such components that are not directly measured, we expect this value never to be equal to zero. The primary unmeasured physiologically active ion is albumen. A normal serum anion gap is measured to be 8 to 16 mEq/L. An increase in the anion gap is associated with renal failure, ketoacidosis, lactic acidosis, and ingestion of toxins, whereas a lowered bicarbonate concentration characterizes a normal anion gap acidosis.

PMID:29493965 | Bookshelf:NBK482340

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