The use of medications such as diuretics as well as medical conditions such as decreased liver and kidney function lead to low sodium levels in the blood, or hyponatremia, in older adults, states Mayo Clinic. Other risk factors include some cancers, underactive thyroid or adrenal glands and antidepressants.
The elderly are prone to low blood sodium levels. They can also have overly high levels of water in the blood, which reduces the overall blood sodium concentration, according to Mayo Clinic. Low blood sodium is most common in elderly people who are hospitalized or are in long-term care facilities as well as those who take medications or have medical conditions that are risk factors.