In a patient whose serum sodium has risen from 129 mEq/L to 139 mEq/L over 24 hours, can a slow intravenous fluid infusion still be administered safely?

Immediate Cessation of All IV Fluids is Required

You must stop all intravenous fluid administration immediately—this patient has experienced dangerously rapid overcorrection of hyponatremia (10 mEq/L rise in 24 hours), which significantly exceeds the maximum safe limit of 8 mEq/L per day and places them at high risk for osmotic demyelination syndrome. 1

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Why Continuing Any IV Fluid is Dangerous

The sodium has risen from 129 to 139 mEq/L over 24 hours—a 10 mEq/L increase that violates the fundamental safety threshold. The maximum correction rate should never exceed 8 mmol/L in any 24-hour period to prevent osmotic demyelination syndrome, which manifests 2–7 days after rapid correction with dysarthria, dysphagia, oculomotor dysfunction, and quadriparesis. 1

Even "slow" isotonic fluids will continue to raise sodium because:

• The patient's underlying hyponatremia mechanism (likely SIADH or hypervolemic state) has resolved or changed
• Any sodium-containing fluid (including 0.9% NaCl at 154 mEq/L) will drive further correction
• The damage from overcorrection accumulates—you cannot "go slower" once the 24-hour limit is breached 1

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Immediate Management Protocol

Step 1: Stop All IV Fluids Now

• Discontinue current fluids immediately 1
• Do not substitute with "slower" isotonic saline—any sodium delivery risks further correction

Step 2: Actively Relower Sodium

Administer 5% dextrose in water (D5W) to provide free water and dilute serum sodium back toward safer correction limits. 1 The goal is to bring the total 24-hour correction back to ≤8 mEq/L from the starting point of 129 mEq/L (target sodium ≈137 mEq/L maximum). 1

Consider desmopressin (DDAVP) to slow or reverse the rapid sodium rise by promoting water retention. 1 This adjunct helps prevent further correction while D5W takes effect.

Step 3: Intensive Monitoring

• Check serum sodium every 2 hours until stabilized 1
• Watch for early signs of osmotic demyelination syndrome over the next 2–7 days: dysarthria, dysphagia, altered mental status, oculomotor abnormalities, quadriparesis 1
• Neurologic examination every 4–6 hours during the acute phase

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Why This Patient is High-Risk

If this patient has any of the following, their risk of osmotic demyelination is even higher with overcorrection:

• Advanced liver disease, alcoholism, malnutrition, or prior encephalopathy—these patients should have had correction limited to 4–6 mEq/L per day, maximum 8 mEq/L in 24 hours 1
• Chronic hyponatremia (>48 hours duration)—rapid correction in chronic cases carries the highest demyelination risk 1

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Common Pitfall You Must Avoid

Never assume that "slowing down" IV fluids after overcorrection has occurred will prevent osmotic demyelination syndrome—the damage is time-dependent and cumulative. 1 Once the 8 mEq/L/24-hour threshold is exceeded, active reversal with D5W ± desmopressin is required, not simply reducing the infusion rate. 1

Do not wait to see if symptoms develop—osmotic demyelination syndrome typically appears 2–7 days after the overcorrection event, and by then the neurologic injury may be irreversible. 1

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Underlying Cause Considerations

Determine why the sodium corrected so rapidly:

• If SIADH was present and has now resolved (e.g., pain/nausea improved, medication discontinued), the patient will excrete free water rapidly and any isotonic fluid will drive correction 1
• If this was hypervolemic hyponatremia (cirrhosis, heart failure) and diuresis occurred, the patient may have shifted to a euvolemic or hypovolemic state where sodium-containing fluids cause rapid correction 1
• If cerebral salt wasting was misdiagnosed as SIADH, aggressive saline administration would cause exactly this overcorrection pattern 1

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Summary Algorithm

1. Stop all IV fluids immediately (including "slow" isotonic saline)
2. Start D5W infusion to actively relower sodium toward safe 24-hour correction limit (≤8 mEq/L from baseline)
3. Consider desmopressin to augment water retention and slow correction
4. Check sodium every 2 hours until stable
5. Monitor neurologic status closely for 7 days for signs of osmotic demyelination syndrome
6. Identify and address the underlying cause of the initial hyponatremia to guide subsequent management once sodium is stabilized 1