Are there any poisons that can cause elevated Blood Urea Nitrogen (BUN) and chloride levels?

Poisons That Can Cause Elevated Blood Urea Nitrogen (BUN) and Chloride Levels

Several poisons can cause elevated BUN and chloride levels, with cyanide being a well-documented toxin that can cause these laboratory abnormalities due to its effects on renal function and acid-base balance.

Mechanisms of BUN Elevation in Poisoning

• Elevated BUN can occur through two primary mechanisms: decreased renal clearance despite normal glomerular filtration or increased urea production 1
• Toxins can cause BUN elevation through:
  • Direct nephrotoxicity leading to acute kidney injury
  • Hemodynamic compromise causing pre-renal azotemia
  • Increased protein catabolism 1

Specific Poisons Associated with Elevated BUN and Chloride

Cyanide

• Cyanide poisoning can cause both lung injury and renal damage, leading to elevated BUN levels 2
• The metabolites of cyanide can cause sudden renal failure, which may require continuous hemofiltration 2
• Elevated chloride levels may occur due to metabolic acidosis and compensatory mechanisms 2

Other Potential Toxins

• Nephrotoxic substances that can cause acute kidney injury may lead to elevated BUN:
  • Heavy metals
  • Certain medications in overdose
  • Industrial chemicals 3
• Substances causing severe dehydration or shock can lead to pre-renal azotemia with elevated BUN and chloride levels 1

Clinical Presentation and Diagnosis

• Patients with toxin-induced elevated BUN may present with:
  • Signs of volume depletion
  • Altered mental status
  • Specific toxidromes depending on the poison 3
• Laboratory evaluation should include:
  • BUN and creatinine measurements
  • Electrolyte panel including chloride
  • Arterial blood gases to assess acid-base status 4

Management Approach

• Initial management focuses on:

  • Stabilization of airway, breathing, and circulation
  • Identification of the specific toxin when possible
  • Contacting regional poison centers (1-800-222-1222 in the US) for expert guidance 3

• For cyanide poisoning specifically:

  • Administer 100% oxygen
  • Perform immediate detoxification with appropriate antidotes
  • Consider continuous renal replacement therapy if renal failure develops 2

• For elevated BUN due to toxin exposure:

  • Assess volume status carefully
  • Administer intravenous fluids if dehydration is present
  • Consider hemodialysis for severe elevations (BUN >100 mg/dL) or if the toxin is dialyzable 4

Monitoring and Follow-up

• Monitor BUN, creatinine, and electrolytes frequently (every 4-6 hours initially) 4
• Maintain accurate intake/output records to track fluid balance 4
• Follow BUN levels serially until normalization 1

Common Pitfalls to Avoid

• Don't assume elevated BUN always indicates kidney dysfunction when creatinine is normal 1
• Avoid laboratory errors in BUN measurement by using proper sampling techniques 4
• Don't delay supportive care while waiting for toxin identification 3