Low blood sodium (hyponatremia) in older adults

My mother's doctor says she has low blood sodium (hyponatremia). What causes this? How is it treated?

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Answer

Hyponatremia occurs when you have an abnormally low amount of sodium in your blood or when you have an excess of water in your blood plasma. Low blood sodium is common in older adults, especially those who are hospitalized or living in long term care facilities. Older adults usually become ill with hyponatremia due to age-related causes that affect the way they metabolize water, such as:

• An excessive water intake
• Less frequent urination
• Changes in the kidneys, such as decreased mass or blood flow

Other factors and conditions that could affect your mother's blood sodium level that aren't related to her water metabolism include:

• Taking certain medications, such as diuretics, antidepressants and pain medications
• Underactive thyroid (hypothyroidism)
• Addison's disease (adrenal insufficiency)
• Severe vomiting or diarrhea
• Cirrhosis
• Kidney failure
• Heart failure
• An excess of anti-diuretic hormone

The signs and symptoms of hyponatremia are nonspecific and occur in many conditions. The only way a doctor can confirm whether you have hyponatremia is by a blood test. Signs and symptoms of hyponatremia may include:

• Nausea
• Headache
• Confusion
• Lethargy
• Decreased consciousness or coma

Severe hyponatremia may lead to rapid, fatal swelling of the brain. Treatment of hyponatremia varies, depending on its cause. Your mother's doctor may try to fix the underlying cause first, such as changing her medication. A second course of action might be to improve her low blood sodium with changes in her water and salt consumption. Your mother's doctor can advise you on the best way to treat her condition.