Safe Correction of Hyponatremia

Initial Assessment and Categorization

Determine the patient’s volume status (hypovolemic, euvolemic, or hypervolemic) using physical examination and laboratory parameters. 1
Classify symptom severity: severe symptoms include altered mental status, seizures, or coma; mild symptoms include nausea, vomiting, or headache. 1
Define chronicity: acute hyponatremia < 48 hours versus chronic ≥ 48 hours or unknown duration. 3
Measure serum and urine osmolality, urine sodium, and uric acid to help identify the underlying etiology. 1

Aim for a rise of 4–6 mmol/L in serum sodium within the first 6 hours (or until severe symptoms resolve). 1
Do not exceed an 8 mmol/L increase in the first 24 hours (some guidelines allow up to 10 mmol/L). 1
After achieving a 6 mmol/L rise in the first 6 hours, limit any further increase to ≤ 2 mmol/L over the next 18 hours to stay within the 24‑hour limit. 1
Check serum sodium every 2 hours while actively correcting. 1
Manage the patient in an intensive‑care setting with strict input‑output monitoring. 1

First‑line: Restrict fluid intake to 1–1.5 L/day. 4
Monitor serum sodium every 4 hours initially, then daily. 2
Second‑line (if fluid restriction fails):
- Oral urea (effective and safe).
- Vasopressin‑receptor antagonists (vaptans) for euvolemic or hypervolemic patients. 4
- Salt tablets (≈ 100 mEq PO three times daily) combined with a high‑protein diet. 2

Replace volume with normal saline. 5
Add fludrocortisone for 7 days in severe cases. 1
Avoid fluid restriction; it markedly raises the risk of cerebral infarction, especially in subarachnoid hemorrhage. 3
In one cohort, 21 of 26 patients who received fluid restriction developed cerebral infarction. 5

Implement sodium and water restriction (fluid intake ≤ 1–1.5 L/day). 4
Adjust or discontinue diuretics and laxatives as appropriate. 4
Consider intravenous albumin based on individual volume assessment. 4
Vaptans may be used for refractory cases. 4
Employ a multidisciplinary approach, involving transplant teams when indicated. 4

Do not correct chronic hyponatremia rapidly because of the risk of osmotic demyelination syndrome. 3
Maximum allowable rise in serum sodium is 8–10 mmol/L within the first 24 hours. 1
Rapid correction (> 1 mmol/L per hour) should be reserved only for severely symptomatic acute hyponatremia. 1
For mild symptoms, check serum sodium every 4 hours initially. 3
Record daily weights, input/output volumes, and reassess volume status throughout treatment. 1

Subarachnoid hemorrhage patients: Treat even mild hyponatremia (serum sodium 131–135 mmol/L) to reduce vasospasm risk. 1
Cirrhosis patients with refractory hyponatremia: Consider transjugular intra‑hepatic portosystemic shunt (TIPS), intravenous vasoconstrictors, or renal replacement therapy. 4