Hyperchloremia Causes and Mechanisms

Primary Causes

Hyperchloremia most commonly results from excessive administration of chloride-rich intravenous fluids, gastrointestinal bicarbonate losses, and renal tubular acidosis, according to Praxis Medical Insights 1

Excessive 0.9% normal saline administration is the most common iatrogenic cause in hospitalized patients, as this solution contains supraphysiologic chloride concentrations compared to plasma 1
Total parenteral nutrition solutions high in chloride content can cause hyperchloremia, especially when sodium is provided predominantly as sodium chloride rather than balanced with sodium acetate or lactate 2 3
Cardiopulmonary bypass priming solutions using unbalanced crystalloids or colloids lead to hyperchloremic acidosis 1

Diarrhea causes hyperchloremia through bicarbonate loss in stool, with compensatory chloride retention by the kidneys to maintain electroneutrality 1
Intestinal fistulas, drainage tubes, and ileostomies result in bicarbonate-rich fluid losses with relative chloride retention 2

The Stewart physicochemical approach explains hyperchloremia's effect on acid-base balance: an increase in plasma chloride relative to sodium decreases the strong ion difference, which directly lowers pH and bicarbonate concentration 3

Premature infants on parenteral nutrition are particularly vulnerable to hyperchloremia when receiving high chloride loads from amino acid solutions and sodium chloride 2 3

Do not assume switching from 0.9% NaCl to 0.45% NaCl resolves hyperchloremia—the latter still contains 77 mEq/L chloride, delivering supraphysiologic concentrations 1
Cumulative chloride from multiple sources often goes unrecognized until significant hyperchloremia develops 2

Patients recovering from diabetic ketoacidosis are at risk of developing hyperchloremia due to excessive saline use for fluid and electrolyte replacement, as chloride from IV fluids replaces ketoanions lost during osmotic diuresis 4
Patients undergoing major abdominal or pancreatic surgery receiving prolonged perioperative fluid therapy are at risk of hyperchloremia 5

Excess 0.9% saline causes hyperosmolar states, hyperchloremic acidosis, and decreased renal blood flow and glomerular filtration rate, which exacerbates sodium retention 5
Hyperchloremic acidosis reduces gastric blood flow, decreases gastric intramucosal pH, and impairs gastric motility 5
Splanchnic edema results in increased abdominal pressure, delayed recovery of gastrointestinal function, increased gut permeability, and potential anastomotic dehiscence 5