Should the urea (Urea) dose be increased in a patient with a decline in sodium levels from 137 to 133 mmol/L after tapering to 15 mg?

Increasing Urea Dose for Declining Sodium Levels

Yes, the urea tablet dose should be increased when sodium levels fall from 137 to 133 mmol/L after tapering to 15 mg. 1, 2

Assessment of Sodium Decline

• A decrease in serum sodium from 137 to 133 mmol/L indicates worsening hyponatremia that requires intervention, as hyponatremia is defined as serum sodium <135 mmol/L 1
• Even mild hyponatremia (133 mmol/L) should not be ignored as it may indicate worsening hemodynamic status and can lead to complications if left untreated 1
• The Neurosurgery society recommends that hyponatremia should be further investigated and treated when serum sodium is less than 131 mmol/L 3

Rationale for Increasing Urea Dose

• Urea is an effective treatment for hyponatremia, with studies showing a median increase of 2 mEq/L per day in serum sodium levels 4
• When urea dose is inadequate, sodium levels can decline, as seen in this patient whose sodium decreased after tapering to 15 mg 1, 5
• Clinical studies show that higher cumulative urea doses are independently associated with greater rises in plasma sodium levels 6

Recommended Approach

• Increase urea dose from the current 15 mg to at least 30 mg/day, which is the median effective dose used in clinical studies 4, 5, 6
• Monitor serum sodium levels daily after increasing the dose to ensure appropriate correction 1
• The goal should be to achieve a serum sodium level ≥130 mmol/L, which is achieved in approximately 64% of patients within 72 hours of appropriate urea dosing 5

Safety Considerations

• Ensure that sodium correction does not exceed 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 1, 3
• Watch for common side effects of urea therapy, which include distaste (reported in 22.7-54% of patients) 5, 7
• Severe side effects are rare, with studies showing no cases of hypernatremia or osmotic demyelination with proper monitoring 5

Long-term Management

• Once serum sodium reaches 131 mmol/L, consider maintaining the higher urea dose rather than tapering again 2
• Continue monitoring serum sodium levels even after stabilization, as recurrence of hyponatremia is common in patients with chronic conditions 2
• If hyponatremia recurs despite adequate urea dosing, consider evaluating for other underlying causes 1