Management of Hyponatremia with Urea Therapy
The urea tablet dose should be increased in this 60-year-old lady whose sodium level fell from 137 to 133 mmol/L after tapering to 15 mg. Urea is an effective treatment for hyponatremia, and the current dose appears insufficient to maintain adequate sodium levels.
Assessment of Current Situation
- The patient's sodium level has decreased from 137 to 133 mmol/L after tapering urea to 15 mg, indicating that the current dose is inadequate to maintain normal sodium levels 1
- While this represents mild hyponatremia (sodium 126-135 mmol/L), even mild hyponatremia requires appropriate management to prevent further decline 1
- A declining trend in sodium levels suggests the need for dose adjustment rather than continued observation 2
Recommended Management
- Increase the urea dose from the current 15 mg to 30 mg daily, as this is the median effective dose shown in clinical studies 2
- Monitor serum sodium levels closely after dose adjustment to ensure appropriate correction without overcorrection 1
- Target a correction rate of no more than 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 1, 3
Evidence Supporting Urea Therapy
- Urea is an effective treatment for hyponatremia with a median increase in serum sodium of 2 mmol/L per day at a median dose of 30 g/day 2
- Studies show significant improvement in serum sodium levels between baseline and discharge with urea therapy (124.2 ± 4 vs 130.1 ± 5.1 mmol/L; P < .001) 2
- In patients with SIADH-induced hyponatremia, urea has been shown to increase sodium levels by a median of 3 mmol/L over the first day of treatment 4
Monitoring Recommendations
- Check serum sodium levels daily after increasing the urea dose 1
- Monitor for signs of overcorrection (increase >8 mmol/L in 24 hours), which occurs in approximately 8% of patients on urea therapy 2
- Assess for patient tolerance, as approximately 23% of patients may experience side effects, primarily related to taste 5
Potential Pitfalls to Avoid
- Inadequate dosing: Starting with doses lower than 30 g/day may be insufficient to correct hyponatremia 5
- Overly rapid correction: Avoid increasing sodium by more than 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 1
- Discontinuing therapy prematurely: Some patients may develop recurrent hyponatremia when urea is stopped, necessitating reintroduction of therapy 6
Long-term Considerations
- If the patient responds well to the increased dose, maintain this dose and monitor sodium levels regularly 7
- Consider addressing any underlying causes of hyponatremia if not already addressed 1
- Be prepared to adjust the dose further if sodium levels continue to decline or if they rise too rapidly 1, 2