A patient with syndrome of inappropriate antidiuretic hormone secretion (SIADH) has a serum sodium of 118 mEq/L and exhibits confusion. Which assessment should the nurse prioritize?

Priority nursing intervention for severe hyponatremia with neurological symptoms is monitoring neurological status and seizure precautions due to risk of cerebral edema and seizures. Other options like hypertonic saline require careful monitoring and are not the initial independent nursing action.

Clinical Priority for Severe Hyponatremia in SIADH

The patient's serum sodium of 118 mEq/L represents severe hyponatremia, and the presence of confusion indicates cerebral edema and neurological involvement. In the context of syndrome of inappropriate antidiuretic hormone secretion (SIADH), the pathological retention of free water leads to a dilutional drop in serum osmolality. Water shifts into brain cells, increasing intracranial pressure and the risk of seizures, coma, or permanent neurological injury. Because the brain is the most vulnerable organ system during acute hyponatremia, the nurse’s immediate priority is to protect the patient from neurological deterioration and seizure activity ^[1].

Rationale for Prioritizing Neurological Monitoring and Seizure Precautions
Severe hyponatremia directly destabilizes neuronal membranes, lowering the seizure threshold. The review by Solares et al. explicitly warns that hyponatremia can cause seizures and emphasizes that correction must be carried out with extreme caution ^[1]. Before any definitive treatment is administered, the nurse must first establish a safe environment and a baseline for ongoing assessment. Monitoring neurological status every 15 minutes allows for early detection of declining mental status, new focal deficits, or seizure activity. Implementing seizure precautions—such as padding side rails, ensuring suction equipment and oxygen are at the bedside, and keeping the bed in the lowest position—directly mitigates the most immediate life-threatening risk.

Analysis of Incorrect Options

Option 1: Administer 3% hypertonic saline solution at 100 mL/hr as ordered.
While hypertonic saline (3% NaCl) is indicated for severe, symptomatic hyponatremia, the prescribed rate of 100 mL/hr is dangerously rapid for a fixed infusion without a clear, weight-based protocol and frequent sodium checks. Overly rapid correction of serum sodium can cause osmotic demyelination syndrome (ODS), a catastrophic neurological complication. The evidence stresses that correction must be slow and cautious ^[1]. The nurse’s priority is not to blindly administer the infusion but to first ensure safety monitoring is in place and to verify the order aligns with safe practice guidelines (typically aiming for a correction of 4–6 mEq/L in the first 24 hours). Administering this rate without immediate, frequent neurological checks and a clear safety baseline would be unsafe.

Option 3: Encourage increased oral fluid intake to improve hydration status.
This action is contraindicated in SIADH. The core pathophysiology of SIADH is excessive water retention due to inappropriately high levels of antidiuretic hormone (ADH). As noted in the literature, SIADH results in "too much" water absorption, which dilutes serum sodium . Encouraging oral fluids would further dilute the serum sodium, worsening cerebral edema and increasing the risk of seizures. The cornerstone of SIADH management is fluid restriction, not fluid encouragement.

Option 4: Restrict dietary sodium intake to prevent further electrolyte imbalance.
This intervention is the opposite of what the patient requires. The primary problem is a deficit of sodium relative to total body water, not an excess. While the body's total sodium content may be normal or slightly high, the concentration is critically low due to dilution. Restricting dietary sodium would not address the dilutional component and could hinder the body's compensatory mechanisms. The management focus is on restricting free water intake and, in severe symptomatic cases, carefully replacing sodium with hypertonic saline [1, 2].