From the Guidelines
Low sodium levels, or hyponatremia, are primarily caused by excessive water intake, certain medications, and underlying medical conditions such as liver cirrhosis, heart failure, and kidney disease, as well as hormonal imbalances and fluid loss through sweating, vomiting, or diarrhea. The causes of hyponatremia can be multifaceted, involving various factors that lead to an imbalance in sodium levels in the body. According to the most recent and highest quality study available, 1, hyponatremia in patients with cirrhosis is often dilutional and requires careful management to prevent further complications.
Causes of Hyponatremia
- Excessive water intake that dilutes sodium levels
- Certain medications like diuretics (e.g., hydrochlorothiazide, furosemide), antidepressants (particularly SSRIs like fluoxetine), and some antiepileptic drugs
- Medical conditions including heart failure, kidney disease, liver cirrhosis, adrenal gland insufficiency, hypothyroidism, and syndrome of inappropriate antidiuretic hormone secretion (SIADH)
- Excessive sweating, vomiting, or diarrhea that deplete sodium through fluid loss
- Drinking too much water during endurance sports without replacing electrolytes
- Hormonal changes affecting water balance in the body, particularly those involving antidiuretic hormone (ADH), leading to water retention and sodium dilution
Management and Treatment
Treatment of hyponatremia depends on the underlying cause and severity but may include:
- Fluid restriction
- Sodium supplementation
- Medication adjustments
- In severe cases, intravenous hypertonic saline solution
- For patients with cirrhosis and hyponatremia, fluid restriction to 1,000 mL/day and cessation of diuretics is recommended for moderate hyponatremia (120-125 mEq/L), and a more severe restriction of water intake with albumin infusion is recommended for severe hyponatremia (<120 mEq/L), as suggested by 1.
It is crucial to address hyponatremia promptly, as severe cases can lead to brain swelling, seizures, and even coma if left untreated. The goal is to correct sodium levels while minimizing the risk of complications such as central pontine myelinolysis, especially in patients with advanced cirrhosis.
From the FDA Drug Label
In two double-blind, placebo-controlled, multi-center studies (SALT-1 and SALT-2), a total of 424 patients with euvolemic or hypervolemic hyponatremia (serum sodium <135 mEq/L) resulting from a variety of underlying causes (heart failure, liver cirrhosis, syndrome of inappropriate antidiuretic hormone [SIADH] and others)
The causes of low sodium levels (hyponatremia) mentioned in the drug label include:
- Heart failure
- Liver cirrhosis
- Syndrome of inappropriate antidiuretic hormone (SIADH)
- Other underlying causes 2
From the Research
Causes of Low Sodium Levels (Hyponatremia)
- Certain medications, such as diuretics, antidepressants, and antiepileptics, can cause hyponatremia 3, 4
- Excessive alcohol consumption can lead to hyponatremia 5
- Very low-salt diets can cause hyponatremia 5
- Excessive free water intake during exercise can result in hyponatremia 5
- Heart failure and cirrhosis are underlying causes of hypervolemic hyponatremia 5, 6
- Syndrome of inappropriate antidiuresis (SIADH) can cause euvolemic hyponatremia 7, 6
- Dehydration resulting from an impaired thirst mechanism or lack of access to water can cause hypernatremia, but hyponatremia can occur due to other causes such as diabetes insipidus 5
Underlying Mechanisms
- Increased release of arginine vasopressin can cause excessive renal retention of water relative to sodium, leading to hyponatremia 6
- Reduced solute-free water clearance can contribute to hyponatremia in patients with cirrhosis and portal hypertension 6
- Certain drugs can affect serum sodium levels by altering the body's ability to regulate water and electrolyte balance 3, 4