What are the causes of hypernatremia, from most common to least common?

From the Guidelines

Hypernatremia is primarily caused by dehydration due to inadequate water intake or excessive water loss, with the most common cause being dehydration, followed by diabetes insipidus, and then less common causes such as iatrogenic factors, primary hyperaldosteronism, and Cushing's syndrome. The causes of hypernatremia can be broken down into the following categories, from most to least common:

• Dehydration due to inadequate water intake, particularly in elderly patients with impaired thirst mechanisms or those unable to access water independently, as well as excessive water loss through increased insensible losses from fever, burns, or hyperventilation, and gastrointestinal losses from diarrhea or vomiting 1.
• Diabetes insipidus, both central (due to inadequate ADH production) and nephrogenic (due to kidney resistance to ADH), which can lead to hypernatremic dehydration, as seen in patients with congenital nephrogenic diabetes insipidus (arginine vasopressin resistance) 1.
• Less common causes, including:
  • Iatrogenic factors such as hypertonic saline administration, sodium bicarbonate therapy, or excessive sodium intake through dietary sources or medications.
  • Primary hyperaldosteronism and Cushing's syndrome, which are rare endocrine causes.
  • Osmotic diuresis from hyperglycemia, mannitol, or urea, which can lead to hypernatremia by increasing renal water excretion. It is essential to note that the underlying pathophysiology of hypernatremia involves disruption of water homeostasis, with serum sodium concentration exceeding 145 mEq/L, reflecting a hyperosmolar state that can cause neurological symptoms ranging from altered mental status to seizures and coma if severe or rapidly developing 1.

From the Research

Causes of Hypernatremia

The causes of hypernatremia can be categorized into two main types: loss of water and gain of sodium, which can be mediated by renal or extrarenal mechanisms 2. The most common causes of hypernatremia are:

• Dehydration, secondary to excess losses of water or hypotonic fluids 3
• Deficit of total body water 2
• Dysfunction of Arginine Vasopressin (AVP), thirst, and the renal response to AVP 4 Other unique circumstances may lead to excess salt, without an impact on the body's total water volume 2.

Common Causes of Hypernatremia

The common causes of hypernatremia, from most to least common, are:

• Hypovolemic hypernatremia, caused by dehydration and loss of water 5
• Hypernatremia due to pure sodium excess, although this is less common 3
• Hypernatremia caused by renal or extrarenal mechanisms, such as diabetes insipidus 6

Less Common Causes of Hypernatremia

Less common causes of hypernatremia include:

• Hypervolemic hypernatremia, caused by excess sodium intake or retention 5
• Hypernatremia caused by other electrolyte disorders, such as hypercalcemia or hypokalemia 6 It is essential to identify the underlying cause of hypernatremia to provide appropriate treatment and prevent complications 6, 5.