What causes hyperchloremia?

Causes of Hyperchloremia

Hyperchloremia is primarily caused by administration of chloride-rich fluids like normal saline, decreased kidney function, water loss exceeding sodium and chloride losses, and conditions resulting in bicarbonate loss rather than acid production. 1

Main Causes of Hyperchloremia

Iatrogenic Causes

• Administration of chloride-rich fluids:
  • 0.9% sodium chloride (normal saline) contains supraphysiologic chloride concentrations 1
  • Excessive use of normal saline is a leading cause of hyperchloremic metabolic acidosis 1, 2
  • Medications with high chloride content 1

Renal Causes

• Decreased kidney function:
  • Reduced ability to excrete excess chloride 1
  • Particularly problematic in patients with CKD, especially with CrCl <30 mL/min 1
  • Renal tubular acidosis (both distal and proximal) 3
  • The renal tubular acidosis of renal insufficiency 3

Volume Status Abnormalities

• Dehydration:
  • Water losses exceeding sodium and chloride losses 4
  • Results in concentration of electrolytes including chloride
• Edematous states:
  • Congestive heart failure, cirrhosis, and nephrotic syndrome 1
  • Impaired ability to excrete free water and sodium

Acid-Base Disturbances

• Normal anion gap metabolic acidosis:
  • Characterized by bicarbonate loss rather than acid production 1, 5
  • Decreased strong ion difference (SID) due to increased chloride relative to sodium 1
• Respiratory alkalosis:
  • Can cause a compensatory rise in chloride 4

Other Causes

• Excessive chloride intake relative to sodium 4
• Overwhelming of chloride handling capacity 4
• Pediatric populations:
  • Neonates and infants with immature renal function 1
  • Limited ability to concentrate urine in preterm and term infants 1

Clinical Approach to Hyperchloremia

Assessment

1. Evaluate volume status
2. Check acid-base status (pH, bicarbonate, anion gap)
3. Assess renal function
4. Review medication list and IV fluid administration
5. Calculate urine anion gap or osmolal gap to distinguish renal from extrarenal causes 3

Management

1. Address underlying cause:

   • Discontinue chloride-rich fluids if iatrogenic 1
   • Switch to balanced electrolyte solutions 1, 2
   • Treat underlying renal disorders if present

2. Fluid management:

   • Use balanced crystalloid solutions rather than 0.9% saline 1
   • Limit 0.9% sodium chloride to maximum 1-1.5L if it must be used 1
   • Replace ongoing losses on a like-for-like basis 1

3. Electrolyte management:

   • Replace sodium using non-chloride salts when appropriate (sodium lactate or sodium acetate) 1
   • Consider sodium bicarbonate if pH < 7.0 in hyperchloremic metabolic acidosis 1

Common Pitfalls

• Failure to recognize the underlying cause can lead to recurrence 1
• Overuse of normal saline can worsen hyperchloremia 1, 2
• Ignoring acid-base status can lead to inadequate treatment 1
• Excessive fluid restriction can worsen hyperchloremia in dehydrated patients 1
• Misdiagnosis as renal tubular acidosis when other conditions may be mimicking it 6
• Inappropriate alkali therapy without proper diagnosis 6