What is the management approach for a patient who has ingested urea?

Management of Urea Ingestion

Urea ingestion is generally considered low toxicity and requires primarily supportive care with monitoring of renal function and electrolytes, as urea is rapidly metabolized and excreted by the kidneys.

Initial Assessment and Monitoring

Immediate evaluation should focus on:

• Volume status assessment - Check for signs of dehydration or volume overload, as urea acts as an osmotic diuretic and increases urinary water excretion 1
• Renal function monitoring - Measure serum urea and electrolytes immediately, as urea is excreted by the kidneys and can accumulate in renal insufficiency 2
• Neurological status - Assess for confusion, as hyperammonemia can occur when urea cannot be adequately detoxified, particularly if there is concurrent renal impairment 2
• Gastrointestinal symptoms - Document nausea, vomiting, or abdominal discomfort, as these are common side effects of urea ingestion 3, 4

Laboratory Investigations

Essential laboratory tests include:

• Serum electrolytes and urea concentrations - Critical for assessing metabolic derangement 2
• Blood urea nitrogen (BUN) - Expect elevation following ingestion, with studies showing BUN increases from baseline 18.4 ± 13.1 to 41.1 ± 26.6 mg/dL with therapeutic urea dosing 4
• Serum sodium - Monitor for changes, as urea can affect sodium balance through its osmotic effects 5, 1
• Renal function parameters - Creatinine and estimated GFR to assess kidney capacity to excrete the urea load 2

Supportive Management

The cornerstone of management is supportive care:

• Hydration - Provide adequate IV fluids to maintain urine output and facilitate urea excretion, targeting urine output of 80-100 mL/m²/h in pediatric patients or 4-6 mL/kg/h if <10 kg 2
• Fluid composition - Use one quarter normal saline/5% dextrose initially, withholding potassium, calcium, and phosphate until electrolyte status is clarified 2
• Urine output monitoring - Maintain close monitoring with target specific gravity of 1.010 2
• Diuretics if needed - If there is no evidence of acute obstructive uropathy or hypovolemia, diuretics may be used to maintain adequate urine output 2

Specific Complications to Monitor

Watch for these potential complications:

• Hyperammonemia - Particularly concerning if renal impairment is present, as ammonia cannot be adequately detoxified when citrulline production is insufficient; confusion is the primary presenting symptom 2
• Electrolyte disturbances - Monitor for hyponatremia or hypernatremia, as urea affects water balance 5
• Gastrointestinal intolerance - Nausea and vomiting are common, with studies showing 53% of patients discontinuing therapeutic urea due to intolerance 4

Common Pitfalls to Avoid

Key considerations in management:

• Do not restrict fluids excessively - Unlike some ingestions, adequate hydration is essential to facilitate urea excretion 2
• Avoid nephrotoxic medications - These could worsen renal function and impair urea clearance 6
• Monitor for overly rapid changes - While urea ingestion typically causes gradual changes, rapid shifts in osmolality can occur 4
• Consider dose-dependent effects - Therapeutic urea dosing ranges from 7.5-90 g/day in studies, so ingested amounts should be quantified if possible 3

Disposition and Follow-up

Most patients can be managed conservatively:

• Observation period - Monitor for 24 hours with serial electrolytes and renal function tests 2
• Discharge criteria - Stable electrolytes, normal renal function, adequate oral intake, and resolution of gastrointestinal symptoms 4
• Outpatient follow-up - Recheck renal function and electrolytes within 3-7 days if any abnormalities were present 2