Mild Hyponatremia at 136 mmol/L: No Workup Needed
For a stable 46-year-old female with a sodium level of 136 mmol/L, no workup is required. This value falls within the normal range (135-145 mmol/L) and does not meet the definition of hyponatremia 1.
Why No Workup Is Necessary
Sodium 136 mmol/L is technically normal – Hyponatremia is defined as serum sodium <135 mmol/L, and this patient's value is above that threshold 1, 2, 3.
Guidelines recommend workup only when sodium drops below 131 mmol/L – The American College of Neurosurgery states that full diagnostic evaluation (serum/urine osmolality, urine electrolytes, volume status assessment) should be pursued when sodium falls below 131 mmol/L 1.
This level is considered acceptable in clinical practice – A sodium of 136 mmol/L is within the range that requires no treatment modification, even in patients with chronic conditions like heart failure or cirrhosis 1.
When to Monitor More Closely
While no immediate workup is needed, certain patient populations warrant closer observation:
Cirrhotic patients – Even mild reductions toward 130 mmol/L may indicate worsening hemodynamic status and increased risk of complications (spontaneous bacterial peritonitis, hepatorenal syndrome, hepatic encephalopathy) 1, 4.
Neurosurgical patients – Mild hyponatremia can progress or indicate underlying pathology like cerebral salt wasting or SIADH, requiring closer monitoring 1.
Patients on high-risk medications – Those taking diuretics, SSRIs, or other medications that can cause hyponatremia should have sodium rechecked if symptoms develop 1.
Practical Management Approach
For this asymptomatic patient with sodium 136 mmol/L:
Continue current management without modification 1.
Recheck sodium in 24-48 hours only if the patient develops symptoms (nausea, headache, confusion, weakness) or has risk factors mentioned above 1.
No fluid restriction, no salt supplementation, no additional testing is indicated at this level 1.
Common Pitfall to Avoid
Do not ignore a downward trend – While 136 mmol/L requires no action, if this represents a decline from previously higher values (e.g., 140 mmol/L), monitor the trajectory. A falling sodium, even within normal range, may signal an evolving problem 1, 4.
The key principle: sodium 136 mmol/L is normal and stable, requiring no intervention unless symptoms develop or the patient has specific high-risk conditions 1, 3.