Episode 198: Hypernatremia

We discuss the approach to diagnosing and managing hypernatremia in the emergency department.

Hosts:
Abigail Olinde, MD
Brian Gilberti, MD

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Episode Overview:

• Introduction to Hypernatremia
• Definition and basic concepts
• Clinical presentation and risk factors
• Diagnosis and management strategies
• Special considerations and potential complications

Definition and Pathophysiology:

• Hypernatremia is defined as a serum sodium level over 145 mEq/L.
• It can be acute or chronic, with chronic cases being more common.
• Symptoms range from nausea and vomiting to altered mental status and coma.

Causes of Hypernatremia based on urine studies:

• Urine Osmolality > 700 mosmol/kg
  • Causes:
    • Extrarenal Water Losses: Dehydration due to sweating, fever, or respiratory losses
    • Unreplaced GI Losses: Vomiting, diarrhea
    • Unreplaced Insensible Losses: Burns, extensive skin diseases
    • Renal Water Losses with Intact AVP Response:
    • Diuretic phase of acute kidney injury
    • Recovery phase of acute tubular necrosis
    • Postobstructive diuresis
• Urine Osmolality 300-600 mosmol/kg
  • Causes:
    • Osmotic Diuresis: High glucose (diabetes mellitus), mannitol, high urea
    • Partial AVP Deficiency: Incomplete central diabetes insipidus
    • Partial AVP Resistance: Nephrogenic diabetes insipidus
• Urine Osmolality < 300 mosmol/kg
  • Causes:
    • Complete AVP Deficiency: Central diabetes insipidus
    ...