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Hyponatremia or hyponatraemia is the condition in which there is abnormally low-level of sodium concentration in blood. Sodium plays a crucial role in regulating the amount of water in the cells and in maintaining blood pressure. It also helps body tissues to function properly.

Drinking too much water makes the sodium concentration outside the cells to drop, and this causes the sodium in the body to become diluted. When this happens, water moves into the cells to balance the levels which causes the cells to swell, and this leads to many health problems. When this swelling happens in the brain cells, it can be fatal as brain cells are sensitive to swelling with no room to expand.


  • Headache
  • Nausea
  • Vomiting
  • Fatigue
  • Loss of Energy
  • Loss of Appetite
  • Confusion
  • Convulsions
  • Restlessness
  • Irritability
  • Muscle Weakness
  • Cramps or Muscle Spasms
  • Seizures
  • Short-Term Memory Loss
  • Lethargy
  • Coma


Several lifestyle factors and health conditions that can lead to hyponatremia are dehydration, diuretic medicines – medicines that increase the flow of urine, which causes the body to get rid of excess water, sweating, liver cirrhosis, Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH), heart failure and burns that affect a large area of the body.

However, water-salt imbalance in the body is caused by one of the following conditions:

  • Hypovolemic hyponatremia :  This condition is due to decrease in total body sodium with comparatively smaller loss in total body water (TBW), and when this happens, the extracellular fluid (ECF) volume is also decreased.
  • Euvolemic hyponatremia : Total body water increases, but the total body sodium stays the same. Although there is ECF volume expansion in the body, there is no presence of edema.
  • Hypervolemic hyponatremia: Both total body sodium and total body water increase, but water gains to a greater extent. The ECF volume is increased with the presence of edema.


The correction or treatment depends on the specific type of hyponatremia whether the patient’s blood volume status is hypervolemic, euvolemic, or hypovolemic. For a mild chronic hyponatremia, treatment may not be required other than change in lifestyle, medication and diet; and for a severe or acute hyponatremia, treatment may include intravenous administration of fluids, water restriction and treatment to abolish any stimuli for ADH secretion such as nausea. Pharmaceutically, Vasopressin Receptor Antagonists (VRA) are used in the treatment of hyponatremia, especially in patients with congestive heart failure, liver cirrhosis or SIADH.