Correcting Sodium from 138 to 135 mmol/L
This is Not Hyponatremia Requiring Correction
A sodium level of 138 mmol/L is within the normal range (135-145 mmol/L), and intentionally lowering it to 135 mmol/L is not a standard clinical practice and carries unnecessary risks. 1, 2, 3
Understanding the Clinical Context
- Normal sodium range is 135-145 mmol/L, with hyponatremia defined as sodium <135 mmol/L 1, 2, 3
- A sodium of 138 mmol/L represents normal physiology and does not require correction 1
- Deliberately inducing hyponatremia (even mild) increases mortality risk 60-fold (11.2% vs 0.19%) and fall risk from 5% to 21% 1, 4
Why This Should Not Be Done
Intentionally lowering sodium from 138 to 135 mmol/L would create iatrogenic mild hyponatremia, which is associated with:
- Cognitive impairment and altered memory 4
- Gait instability and increased fall risk 4, 3
- Increased hospital mortality 1, 4
- Nausea, vomiting, weakness, and headaches 4
If This Question Reflects a Misunderstanding
If you meant correcting FROM 135 TO 138 (treating hyponatremia):
For mild hyponatremia (135 mmol/L), treatment focuses on addressing the underlying cause rather than aggressive sodium correction. 1, 2
- Assess volume status (hypovolemic, euvolemic, or hypervolemic) 1, 2
- For hypovolemic: discontinue diuretics and provide isotonic saline 1
- For euvolemic (SIADH): fluid restriction to 1 L/day 1
- For hypervolemic (heart failure, cirrhosis): fluid restriction to 1-1.5 L/day 1
- Maximum correction rate: 8 mmol/L per 24 hours to prevent osmotic demyelination syndrome 1, 5, 2
If you meant correcting hypernatremia FROM 138 TO 135:
A sodium of 138 mmol/L is not hypernatremia (hypernatremia is defined as >145 mmol/L) 6
Critical Safety Point
Any intentional manipulation of sodium levels outside the normal range without clear medical indication violates the principle of "first, do no harm." 1, 4 The risks of inducing electrolyte abnormalities far outweigh any theoretical benefit of moving from 138 to 135 mmol/L.