From the Guidelines
Low sodium, or hyponatremia, is primarily caused by conditions such as heart failure, kidney disease, liver cirrhosis, and syndrome of inappropriate antidiuretic hormone secretion (SIADH), as well as excessive water intake and certain medications like diuretics and antidepressants. When considering the etiology of hyponatremia, it is crucial to differentiate between hypovolemic, euvolemic, and hypervolemic hyponatremia, as treatment approaches vary significantly based on the underlying cause and volume status of the patient 1. Some key causes of low sodium include:
- Excessive water intake
- Medications like diuretics (such as hydrochlorothiazide, furosemide) and antidepressants (particularly SSRIs like fluoxetine)
- Medical conditions including heart failure, kidney disease, liver cirrhosis, adrenal gland insufficiency (Addison's disease), hypothyroidism, and SIADH
- Excessive sweating, vomiting, or diarrhea
- Certain endurance sports when athletes drink too much water without replacing electrolytes
- Nutritional factors like beer potomania or tea and toast syndrome in elderly people The management of hyponatremia, as outlined in the 2021 practice guidance by the American Association for the Study of Liver Diseases, depends on the etiology, chronicity, severity, and urgency of the condition, with acute hyponatremia requiring rapid correction and chronic hyponatremia necessitating more gradual correction to avoid osmotic demyelination syndrome (ODS) 1. Treatment strategies for hypovolemic hyponatremia involve discontinuing diuretics and/or laxatives and providing fluid resuscitation, typically with 5% IV albumin or crystalloid solution, while euvolemic hyponatremia management is based on the specific underlying cause, and hypervolemic hyponatremia treatment includes fluid restriction, reduction or discontinuation of diuretics and laxatives, administration of hyperoncotic albumin, and/or vasopressin receptor antagonists (“vaptans”) 1.
From the Research
Causes of Low Sodium
- Thiazide diuretics can cause low sodium levels by impairing the body's ability to dilute urine, leading to water retention and cation depletion 2
- The use of thiazide diuretics can also stimulate the release of vasopressin, which can further contribute to low sodium levels 2
- Selective serotonin reuptake inhibitors (SSRIs) can cause low sodium levels by triggering the syndrome of inappropriate antidiuretic hormone secretion (SIADH) 3
- The combined use of thiazide diuretics and SSRIs can increase the risk of low sodium levels due to a synergistic effect on impairing renal free water clearance 3, 4
- The risk of low sodium levels is higher in older adults, particularly those taking both thiazide diuretics and SSRIs, with a prevalence of approximately 13.0% in patients taking both medications 4
- Other factors that can contribute to low sodium levels include:
- Inadequate dietary intake of sodium
- Excessive water intake
- Certain medical conditions, such as heart failure or liver disease
- The use of other medications that can affect sodium levels, such as loop diuretics or vasopressin receptor antagonists 5