What causes hyperchloremia?

Causes of Hyperchloremia

Hyperchloremia is primarily caused by excessive chloride administration (especially through normal saline), dehydration, renal tubular dysfunction, or metabolic acidosis with normal anion gap. 1

Primary Mechanisms of Hyperchloremia

Hyperchloremia occurs through several key mechanisms:

1. Excessive Chloride Administration

   • Infusion of chloride-rich fluids, particularly 0.9% normal saline which contains supraphysiologic chloride concentrations (154 mmol/L) 1, 2
   • Administration of medications with high chloride content (e.g., certain antibiotics like benzylpenicillin) 3

2. Dehydration and Volume Depletion

   • Water losses exceeding sodium and chloride losses 4
   • Conditions with excessive free water loss (e.g., diabetes insipidus, severe diarrhea)

3. Renal Dysfunction

   • Tubular dysfunction with impaired chloride excretion 5
   • Distal renal tubular acidosis (RTA) 6
   • Proximal renal tubular acidosis 6
   • Chronic kidney disease with greater tubular than glomerular dysfunction 5

4. Acid-Base Disorders

   • Normal anion gap metabolic acidosis (chloride increases as bicarbonate decreases) 4, 6
   • Respiratory alkalosis (compensatory mechanism) 4
   • Hyperchloremic metabolic acidosis from bicarbonate loss 7

5. Electrolyte Imbalances

   • Excessive loss of sodium relative to chloride 7
   • Excessive gain of chloride relative to sodium 7

Clinical Context and Associations

• Perioperative Setting

  • Common during and after surgery due to administration of chloride-rich fluids 2
  • Cardiopulmonary bypass procedures using normal saline or unbalanced colloid solutions 3

• Critical Illness

  • Resuscitation with large volumes of normal saline 1, 2
  • Impaired renal function in critically ill patients 5

• Pediatric Considerations

  • Immature renal function in neonates and infants affects chloride handling 3
  • Limited ability to concentrate urine in preterm and term infants 3

Physiological Impact

• Hyperchloremia decreases the strong ion difference (SID), leading to metabolic acidosis 3
• The SID is calculated as the difference between strong cations (Na+, K+, Ca2+, Mg2+) and strong anions (Cl-, lactate) 3
• An increase in plasma chloride relative to sodium decreases plasma SID and lowers pH 3, 2

Common Pitfalls in Management

• Failure to recognize the underlying cause of hyperchloremia can lead to recurrence 1
• Overuse of normal saline can worsen hyperchloremia due to its high chloride content 1, 2
• Ignoring acid-base status when treating hyperchloremia can lead to inadequate management 1
• Excessive fluid restriction in dehydrated patients can worsen hyperchloremia 1

Understanding the specific cause of hyperchloremia is essential for appropriate management, which should focus on addressing the underlying etiology while avoiding chloride-rich solutions that could exacerbate the condition.