Long-Term Care

Understanding hyponatremia and hypernatremia in dehydration

LTC Nursing Assistant Trainer, December 3, 2009

Many elderly long-term care facility residents are found to be dehydrated with hypovolemia, or low circulating blood volume. Some are diagnosed with hyponatremia, and others are diagnosed with hypernatremia. Long-term care nurses must be able to identify these conditions on laboratory reports and know how to prevent them from developing.

Hyponatremia occurs when the sodium level in the blood is low or the resident is in fluid overload. Although there are other causes, hyponatremia commonly develops in elderly residents as a result of excessive intake or excretion of dietary sodium or water, certain diseases, consuming a low-salt diet for prolonged periods, excessive sweating, severe or prolonged diarrhea, or taking diuretics, which increase the excretion of sodium into urine.

Hypernatremia is almost always an indication of excessive fluid depletion. It usually occurs with inadequate fluid intake and increased water loss. It commonly develops in elderly residents as a result of:

  • Certain diseases and medical conditions
  • Physical or mental inability to consume sufficient fluids
  • Lack of thirst
  • Conditions that override the body’s volume control mechanisms, usually excessive diuresis or diabetes insipidus
  • Fever
  • Vomiting
  • Diarrhea
  • Loss of excessive water through the kidneys
  • Receiving tube feedings with inadequate free water

This is an excerpt from HCPro's book, The Long-Term Care Nursing Desk Reference, Second Edition, by Barbara Acello, MS, RN.

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