Hyponatremia: What Causes Low Sodium Levels?

What Is Hyponatremia?

low sodium levels

Hyponatremia refers to low sodium levels in the blood. It is essential for sodium levels to remain balanced and when they drop too low, it can lead to serious medical complications if not remedied. Low sodium levels are considered any measurement under 135 mmol/L. Measurements under 120 mEq/L. Hyponatremia can occur suddenly or gradually over a period of time, depending on the underlying cause. Hyponatremia is very common, with more than 200,000 new cases reported every year in the US.


  • Dehydration
  • Severe vomiting
  • Intestinal obstruction
  • Severe diarrhea
  • Intestinal fistulas
  • Heart disease
  • Kidney disease
  • Liver disease
    Certain medications

    • Direutics
    • Anti-depressants
    • Pain relievers
  • Syndrome of inappropriate antidiurectic hormone- SIADH
  • Surgery and trauma
  • Stroke
  • Over-hydration


True Hyponatremia

True hyponatremia is the most common type of hyponatremia. It is also known as hypotonic hyponatremia and is characterized by varying degrees of the patient’s blood volume.

Acute Hyponatremia

Acute hyponatremia refers to low sodium levels that occur rapidly, typically due to dehydration from severe vomiting or diarrhea.

Chronic Hyponatremia

Chronic hyponatremia refers to sodium levels that gradually decrease over time due to an chronic underlying condition, such as kidney disease or liver disease.


  • Nausea
  • Vomiting
  • Seizures
  • Lethargy
  • Cramps
  • Diarrhea
  • Confusion
  • Fatigue
  • Memory Loss
  • Irritability
  • Muscle Weakness
  • Loss of Appetite



If your primary care physician feels that you are exhibiting symptoms of hyponatremia, a simple blood panel can reveal that your sodium levels are low. Many cases of hyponatremia are diagnosed by emergency room physicians because patients typically wait until symptoms are severe to seek medical treatment.


Treating hyponatremia depends on the severity of the condition and the underlying cause. Moderate to severe hyponatremia is typically treated with saline intravenous fluids during hospitalization. These IV fluids should contain an adequate amount of sodium to properly balance the patient’s sodium levels. It is important to not give the patient too much sodium too quickly, as it can cause central pontine myelinolysis, a neurological condition in which the myelin sheaths of the nerve cells become damaged. Treating hyponatremia that is mild or asymptomatic usually depends on the underlying cause. If a certain medication is cause the low sodium levels, eliminating or changing the dosage of that medication can resolve the hyponatremia.

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