What is the treatment approach for urea fertilizer ingestion?

Treatment Approach for Urea Fertilizer Ingestion

The treatment of urea fertilizer ingestion requires immediate medical attention with supportive care, gastrointestinal decontamination, and hemodialysis for severe cases with hyperammonemia, hyperkalemia, or methemoglobinemia.

Initial Assessment and Stabilization

• Assess airway, breathing, and circulation as with any poisoning case 1
• Monitor vital signs closely, as cardiovascular instability may develop rapidly 2
• Obtain baseline laboratory studies including:
  • Complete blood count
  • Comprehensive metabolic panel (with particular attention to potassium levels)
  • Arterial blood gas with co-oximetry (to assess for methemoglobinemia)
  • Serum ammonia levels 3
  • Blood urea nitrogen and creatinine 1

Gastrointestinal Decontamination

• If the patient presents within 1 hour of ingestion and is alert with intact airway reflexes, consider:
  • Activated charcoal administration (though efficacy for urea is limited)
  • Gastric lavage for large ingestions 4
• Do not induce vomiting as this may worsen esophageal injury if corrosive components are present in the fertilizer 1

Management of Specific Complications

Hyperammonemia

• Hyperammonemia occurs due to the conversion of urea to ammonia 3
• Monitor ammonia levels closely, as elevated levels can cause cerebral edema and neurological damage 5
• For severe hyperammonemia (>100 μmol/L):
  • Initiate hemodialysis to rapidly remove ammonia 5
  • Consider administration of sodium benzoate and phenylacetate if available (these medications help with alternative nitrogen excretion pathways) 5

Methemoglobinemia

• Urea fertilizers can cause methemoglobinemia, especially those containing urea herbicides 4
• For symptomatic methemoglobinemia or levels >30%:
  • Administer methylthioninium chloride (methylene blue) 1-2 mg/kg IV over 5-10 minutes 4
  • Monitor response and repeat if necessary

Hyperkalemia

• Hyperkalemia is a potentially life-threatening complication of urea fertilizer ingestion 1
• For severe hyperkalemia with ECG changes:
  • Administer calcium gluconate 10% solution (10 mL IV)
  • Give insulin (10 units regular) with glucose (50 mL of 50% dextrose)
  • Consider sodium bicarbonate for metabolic acidosis
  • Initiate emergent hemodialysis for refractory cases 1

Renal Failure

• Acute kidney injury may develop following fertilizer ingestion 1
• Monitor urine output and renal function tests
• Maintain adequate hydration with IV fluids
• Initiate hemodialysis for:
  • Severe metabolic acidosis
  • Fluid overload unresponsive to diuretics
  • Uremic symptoms
  • Persistent hyperkalemia 1

Supportive Care

• Maintain fluid and electrolyte balance 1
• Provide respiratory support as needed
• Monitor neurological status for signs of cerebral edema 5
• Treat seizures if they occur with benzodiazepines

Monitoring and Follow-up

• Continue monitoring of:
  • Vital signs
  • Neurological status
  • Renal function
  • Electrolytes
  • Ammonia levels 3, 5
• Most patients with adequate treatment will recover renal function within days 1

Common Pitfalls and Caveats

• Do not delay hemodialysis in patients with severe hyperkalemia or signs of hemodynamic instability 1
• Be vigilant for delayed onset of methemoglobinemia, which may not be apparent on initial presentation 4
• Remember that clinical symptoms may not correlate with ammonia levels, so treat based on both clinical presentation and laboratory values 5
• Consider the possibility of additional toxins in the fertilizer formulation that may require specific antidotes or treatments 2