From the Guidelines
Hyponatremia is caused by multiple factors that disrupt the body's sodium and water balance, including excessive water intake, medications, hormonal conditions, heart, liver, or kidney diseases, and certain endocrine disorders, as noted in the most recent guidelines 1. The main causes of hyponatremia can be categorized into:
- Excessive water intake (polydipsia), which dilutes sodium levels
- Medications such as diuretics, antidepressants (particularly SSRIs), and certain antiepileptics that affect water retention
- Hormonal conditions like SIADH (Syndrome of Inappropriate Antidiuretic Hormone secretion) and adrenal insufficiency
- Heart, liver, or kidney diseases that impair the body's ability to regulate fluids
- Excessive sweating or vomiting without adequate sodium replacement
- Certain endocrine disorders like hypothyroidism
- Drinking too much water during endurance exercise without electrolyte replacement
- Medical conditions that cause fluid shifts, such as severe burns or pancreatitis The underlying mechanism typically involves either sodium loss, water retention, or a combination of both, disrupting the normal serum sodium concentration of 135-145 mEq/L, as discussed in 1 and 1. Symptoms of hyponatremia vary based on severity and onset speed, ranging from mild headache and confusion to seizures and coma in severe cases, and treatment depends on identifying and addressing the specific cause while carefully correcting sodium levels to prevent complications from overly rapid correction, as emphasized in 1. It is essential to note that the treatment of hyponatremia should be tailored to the underlying cause, and the most recent guidelines 1 provide a comprehensive approach to managing hyponatremia in patients with cirrhosis and ascites.
From the Research
Causes of Hyponatremia
The causes of hyponatremia can be categorized based on the patient's fluid volume status, which includes hypovolemic, euvolemic, and hypervolemic hyponatremia 2, 3.
- Hypovolemic hyponatremia is often caused by excessive loss of sodium and water, which can occur due to various factors such as diuretic use, gastrointestinal losses, or renal losses 3, 4.
- Euvolemic hyponatremia is commonly caused by the syndrome of inappropriate antidiuresis (SIADH), which can be triggered by certain medications, lung diseases, or neurological disorders 2, 3.
- Hypervolemic hyponatremia is often associated with heart failure, cirrhosis, or nephrotic syndrome, where there is an excess of total body sodium and water 2, 5, 6.
Common Causes of Hyponatremia
Some common causes of hyponatremia include:
- Certain medications, such as diuretics, which can lead to excessive loss of sodium and water 4.
- Excessive alcohol consumption, which can cause hyponatremia due to poor dietary intake and increased excretion of sodium 3.
- Very low-salt diets, which can lead to hyponatremia due to inadequate sodium intake 3.
- Excessive free water intake during exercise, which can cause hyponatremia due to dilution of sodium in the blood 3.
- Heart failure, which can cause hyponatremia due to increased activity of arginine vasopressin (AVP) and subsequent water retention 6.
- Cirrhosis, which can cause hyponatremia due to increased release of AVP and subsequent water retention 5.