Low Sodium Levels in Premature Infants

Premature infants are those born before 37 weeks of gestation. According to the Penn State Children’s Hospital, premature infants, who are not fully developed when born, can have serious medical conditions, including breathing difficulty, inability to maintain appropriate growth or obtain adequate nutrition, susceptibility to infections, and problems maintaining fluid and electrolyte balance. One of the electrolytes affected in premature infants is sodium. Low sodium levels, or hyponatremia, in premature infants can have serious health consequences.


Premature infants have a higher content of water than full term infants, but also have a higher possibility of losing fluids through evaporation. Dehydration and inadequate fluid and nutritional intake by the premature infant can lead to low sodium level. Also, excess fluid administration, particularity too much intravenous fluids, can dilute the levels of sodium in the blood. Other causes include administration of diuretics, medicines that increase the excretion of fluid and sodium from the kidneys and that in the premature infant are used for bronchopulmonary dysplasia, a chronic lung condition.


Newborn baby in incubator

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The symptoms of low sodium or hyponatremia in premature infants are sometimes hard to detect, but relate to the brain swelling that occurs when sodium levels drop suddenly. Brain swelling occurs because water goes to the area of the body with higher sodium content. When the sodium level in the blood of a premature infant drops, the brain maintains its sodium supply, making water flow into it and causing edema or swelling. According to Nelson’s Essentials of Pediatrics, the symptoms of brain edema include:

  • irritability
  • lethargy
  • agitation,
  • nausea

If the condition worsens, infants can have seizures and may even fall in a state of coma.


Judicious correction of fluid and sodium balance is the best strategy for correcting hyponatremia. Supplementation with intravenous fluids is usually the initial treatment, with close monitoring of sodium blood levels and urine output. Too rapid correction of hyponatremia can cause destruction of the covering of the brainstem cells and lead to long-term disability.


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Premature infants need to be placed in incubators to maintain their temperature and prevent excess fluid losses. Frequent monitoring of electrolyte levels, including sodium, and appropriate use of intravenous fluids and medicines can prevent sudden drops in sodium levels. If the infant exhibits signs of brain swelling, rapid correction of sodium levels may be necessary, but only with close monitoring in a neonatal intensive care unit.