From the Guidelines
Hypernatremia is primarily caused by water loss exceeding sodium loss, and the most common causes include inadequate water intake, excessive water loss through the kidneys, gastrointestinal losses, skin losses, and respiratory losses, as well as iatrogenic causes and certain medications. The body's defense mechanisms against hypernatremia, such as thirst and antidiuretic hormone (ADH) release, can be impaired in certain individuals, leading to the development of hypernatremia 1.
Common Causes of Hypernatremia
- Inadequate water intake, often seen in elderly or disabled patients who cannot access water
- Excessive water loss through the kidneys, such as in diabetes insipidus 1
- Gastrointestinal losses, including severe diarrhea or vomiting
- Skin losses, such as extensive burns or excessive sweating
- Respiratory losses, including patients with fever or on ventilators
- Iatrogenic causes, such as administration of hypertonic sodium solutions, improper formula preparation for infants, or excessive sodium bicarbonate administration
- Certain medications, like mannitol, lactulose, or lithium, which can induce osmotic diuresis leading to hypernatremia
Rare Causes of Hypernatremia
- Primary hyperaldosteronism
- Cushing's syndrome
Impaired Defense Mechanisms
- Altered mental status
- Infants
- Patients without access to water
Treatment
Treatment of hypernatremia focuses on addressing the underlying cause while carefully correcting sodium levels to prevent complications like cerebral edema 1. In cases of hypernatremic dehydration, treatment with water and dextrose is recommended, avoiding salt-containing solutions to prevent further renal osmotic load 1. The initial rate of fluid administration should be calculated based on physiological demand, taking into account the patient's weight and age 1.
From the Research
Causes of Hypernatremia
The causes of hypernatremia can be categorized into several key areas, including:
- Dehydration resulting from an impaired thirst mechanism or lack of access to water 2
- Diabetes insipidus, a condition where the body is unable to regulate fluids properly 2, 3
- Excess losses of water or hypotonic fluids 4
- Pure sodium excess, although this is less common 4
- Certain medications, such as those used to treat diabetes insipidus, which can affect water balance 3
- Renal or extrarenal mechanisms that lead to a loss of water or gain of sodium 5
Pathogenesis and Clinical Characteristics
Hypernatremia can result from a variety of pathogenic mechanisms, including:
- Essential hypernatremia, a rare condition characterized by chronic and sustained hypernatremia, absence of thirst, and normal renal function 6
- Central diabetes insipidus, a condition where the body is unable to produce antidiuretic hormone (ADH), leading to an inability to regulate fluids properly 6, 3
- Adypsia, a condition characterized by a lack of thirst, which can contribute to the development of hypernatremia 6
Diagnosis and Management
Diagnosis and management of hypernatremia involve identifying the underlying cause and correcting the fluid deficit 2, 5. Treatment may include: