From the Guidelines
Hyponatremia is primarily caused by an imbalance in the body's sodium-water balance, often resulting from excessive water intake, increased antidiuretic hormone (ADH) secretion, kidney disorders, certain medications, and medical conditions like heart failure, cirrhosis, and adrenal insufficiency, as noted in the 2021 practice guidance by the American Association for the Study of Liver Diseases 1. The causes of hyponatremia can be broadly categorized into hypovolemic, euvolemic, and hypervolemic types, each with distinct underlying mechanisms and treatment approaches.
- Hypovolemic hyponatremia is often caused by excessive diuretic use, leading to dehydration and a decrease in serum sodium levels, as discussed in the 2018 Clinical and Molecular Hepatology guidelines 1.
- Hypervolemic hyponatremia, commonly seen in patients with cirrhosis, results from non-osmotic hypersecretion of vasopressin and enhanced proximal nephron sodium reabsorption, impairing free water clearance, as explained in the 2018 Journal of Hepatology guidelines 1.
- Euvolemic hyponatremia may be caused by various factors, including the syndrome of inappropriate antidiuretic hormone secretion (SIADH), hypothyroidism, and certain medications, as mentioned in the 2021 Gut guidelines 1. It is essential to identify the underlying cause of hyponatremia to provide appropriate treatment, which may include fluid restriction, discontinuation of diuretics, administration of hypertonic saline, or vasopressin receptor antagonists, depending on the severity and etiology of the condition, as outlined in the 2021 Hepatology practice guidance 1. Careful monitoring of serum sodium levels is crucial during treatment to avoid overcorrection and the risk of osmotic demyelination syndrome, particularly in patients with chronic hyponatremia, as emphasized in the 2021 practice guidance by the American Association for the Study of Liver Diseases 1.
From the FDA Drug Label
10 OVERDOSAGE Overdosage with vasopressin injection can be expected to manifest as consequences of vasoconstriction of various vascular beds (peripheral, mesenteric, and coronary) and as hyponatremia.
6 ADVERSE REACTIONS ... Metabolic: Hyponatremia
The causes of hyponatremia include vasopressin overdosage 2 and vasopressin use 2.
- Vasopressin can cause hyponatremia as a consequence of its use or overdosage.
- The exact mechanism of how vasopressin causes hyponatremia is not explicitly stated in the provided drug labels, but it is related to its antidiuretic effect via V2 receptors 2.
From the Research
Causes of Hyponatremia
The causes of hyponatremia can be classified into several categories, including:
- Pseudohyponatremia, which occurs due to hyperproteinemia, hyperlipidemia, or hyperglycemia 3
- Hypovolemic hyponatremia, commonly caused by fluid loss 3, 4, 5
- Hypervolemic hyponatremia, often resulting from fluid retention due to heart failure, cirrhosis, or renal failure 3, 4, 6, 5
- Euvolemic hyponatremia, most often caused by the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) 3, 4, 5
Underlying Causes
Some specific underlying causes of hyponatremia include:
- Excessive antidiuretic hormone secretion 6, 5
- Heart failure 4, 6, 5
- Liver cirrhosis 4, 5
- Renal failure 3, 4
- Certain medications 7
- Excessive alcohol consumption 7
- Very low-salt diets 7
- Excessive free water intake during exercise 7
Classification of Hyponatremia
Hyponatremia can be classified based on the patient's fluid volume status, including: