Hyponatremia is a condition where the sodium level in the blood drops below normal. Typically, sodium levels should be between 135–145 milliequivalents per liter (mEq/L). If it falls below 135 mEq/L, it is considered hyponatremia, which can affect water balance, the nervous system, muscles, and blood pressure. Sodium is an essential mineral that helps maintain fluid balance within the body. When sodium levels are low, water moves into cells more, especially in the brain, which can cause dangerous symptoms such as brain swelling, loss of consciousness, or death.
Causes of Hyponatremia
It can occur due to various factors and can be divided into 3 major groups based on the body’s water balance
1. Decreased water and sodium (Hypovolemic Hyponatremia)
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- Loss of water and electrolytes from vomiting or diarrhea
- Excessive sweating from exercise or hot weather
- Long-term use of diuretics
- Significant blood or fluid loss from wounds or surgery
2. Excess water (Hypervolemic Hyponatremia)
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- Heart failure
- Cirrhosis
- Chronic kidney disease. These conditions cause the body to retain more water than usual, resulting in diluted sodium in the blood.
3. Normal water but low sodium (Euvolemic Hyponatremia)
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- Caused by abnormalities of the ADH hormone (SIADH) which is often detected with associated diseases later, such as pneumonia or tumors
- Excessive water intake and poor nutrition, such as psychiatric patients who drink large amounts of water or alcoholic patients with malnutrition
- Hypothyroidism and adrenal insufficiency
- Use of certain medications such as antidepressants, anticonvulsants, or diuretics
Symptoms of Hyponatremia depend on the severity and speed of sodium level reduction in the blood. Initial symptoms
- Fatigue
- Nausea
- Muscle cramps or weakness
Severe Symptoms (Emergency)
- Drowsiness, confusion, incoherent speech
- Loss of consciousness or seizures
- Unconsciousness (coma)
If a patient exhibits these symptoms, they should be urgently taken to the hospital to prevent brain swelling or death.
Diagnosis of Hyponatremia Doctors will perform blood tests to directly measure sodium levels. If below 135 mEq/L, hyponatremia is diagnosed. Additionally, doctors may perform further tests such as
- Osmolality tests of blood and urine
- Sodium level tests in urine
- Kidney, liver, and heart function tests to find the underlying cause
Treatment Guidelines for Mild Hyponatremia
- Limit water intake
- Adjust or stop certain medications, such as diuretics
- Supplement electrolytes as recommended by a doctor
Moderate to Severe Hyponatremia
- Administer concentrated saline (Hypertonic saline) intravenously
- Monitor in the intensive care unit (ICU)
- Adjust sodium levels slowly to prevent Osmotic Demyelination Syndrome (ODS), which occurs from rapid sodium level increase
Treating the Underlying Cause
- Control heart, liver, or kidney diseases if they are the main causes
- Treat hormonal or thyroid abnormalities
Prevention of Hyponatremia
- Drink an appropriate amount of water, not too much or too little
- If exercising intensely, drink electrolyte drinks instead of plain water alone
- Avoid unnecessary use of diuretics
- Have regular health check-ups, especially for those with chronic diseases such as heart, liver, or kidney disease
- Consult a doctor before using medications that may affect sodium levels
Hyponatremia (Hyponatremia) may seem minor, but if left untreated, it can be life-threatening, especially in the elderly or patients with chronic diseases. If symptoms such as weakness, confusion, or seizures occur, immediate medical attention is necessary.
Dr. Methinee Sutthiwaikit
Nephrologist
Dialysis Center, Phyathai 2 Hospital
