What causes hypernatremia?

Critical Emergency: Sodium 295 mEq/L Represents Life-Threatening Hypernatremia

A sodium level of 295 mEq/L is a medical emergency requiring immediate intervention, as this represents severe hypernatremia (>145 mEq/L) that can cause profound neurological dysfunction, seizures, coma, and death from cellular dehydration and potential vascular rupture. 1, 2

Immediate Causes to Identify

Your sodium is critically elevated due to one or more of these mechanisms:

Water Loss (Most Common)

• Inadequate fluid intake due to impaired thirst mechanism, altered mental status, or lack of access to water 3, 4
• Gastrointestinal losses from severe diarrhea, vomiting, or drainage tubes 3
• Excessive sweating without adequate water replacement 3
• Renal water losses from diabetes insipidus (central or nephrogenic) where kidneys cannot concentrate urine 3, 5
• Severe burns causing voluminous fluid losses 3

Excessive Sodium Administration (Less Common)

• Iatrogenic sodium overload from hypertonic saline, sodium bicarbonate infusions, or incorrect parenteral nutrition 3, 5
• Excessive diuretic use causing disproportionate water loss 3

High-Risk Clinical Contexts

• Hospitalized patients with inadequate fluid prescription 3
• ICU patients who are sedated, intubated, or have altered mental status preventing water intake 2
• Patients on medications causing increased water loss (diuretics, caffeine) 3

Diagnostic Workup Required

Check urine osmolality and urine sodium immediately to determine if your kidneys are appropriately concentrating urine 3:

• High urine osmolality (>600 mOsm/kg): Suggests extrarenal water losses (GI losses, sweating, burns)
• Low urine osmolality (<300 mOsm/kg): Suggests diabetes insipidus (renal concentrating defect) 5

Critical Management Principles

For chronic hypernatremia (>48 hours), correction must NOT exceed 10-15 mmol/L per 24 hours to prevent cerebral edema, seizures, and neurological injury. 3, 6 At your sodium level of 295 mEq/L, this is almost certainly chronic.

Correction Strategy

• Initial target: Reduce sodium by maximum 0.4 mmol/L per hour or 8-10 mmol/L per day 6, 5
• Use hypotonic fluids (5% dextrose in water or 0.45% saline) for water replacement 6, 4
• Monitor sodium levels every 2-4 hours during active correction to prevent overly rapid drops 6, 2
• Address underlying cause simultaneously while correcting water deficit 3

Special Considerations

• If diabetes insipidus is identified: Desmopressin (DDAVP) may be required 6
• If acute hypernatremia (<24 hours): Hemodialysis can rapidly normalize sodium, but this is rarely the case at such extreme levels 6
• Avoid rapid correction: Osmotic demyelination syndrome risk is present with overly aggressive treatment 6, 1

Common Pitfalls to Avoid

• Never correct chronic severe hypernatremia rapidly - this causes more harm than the hypernatremia itself through cerebral edema 3, 6, 1
• Do not use normal saline (0.9% NaCl) as primary replacement fluid - this contains too much sodium (154 mEq/L) 4
• Do not delay treatment while pursuing extensive diagnostic workup - begin hypotonic fluid replacement immediately 4
• Monitor closely if starting dialysis - can cause dangerous rapid sodium drops in chronic hypernatremia 6