What causes low sodium?

A reader, 67, wants to know about low sodium.

“I’ve had very low sodium for a long time,” she writes, “and it prevents me from having necessary surgeries.”

Dr. Mike Jeong, a geriatric medicine specialist and associate professor at Touro University Nevada College of Osteopathic Medicine, notes that sodium is an electrolyte, “which means it’s an essential component of our cellular makeup. It helps regulate many of our systems, including our nervous system.”

Hyponatremia, or low sodium, can occur as a function of aging, as physiological and hormonal changes affect the kidneys, which help to regulate the balance of sodium in the body.

Symptoms of hyponatremia, can include excessive thirst, a sense of lethargy or disorientation, loss of appetite, nausea, muscle cramping and headaches, Jeong says. In severe, acute cases, hyponatremia also can cause swelling in the brain.

“Mostly, for the elderly, neurological symptoms seem to be the first thing to manifest,” he adds.

Hyponatremia can be diagnosed through a blood test called a metabolic panel and a physical examination. The task then becomes trying to determine what, among many possibilities, might be causing it.

Among the possibilities, according to Jeong, are decreased salt intake, perhaps through excessive sweating because of an illness; gastrointestinal sodium loss in the form of diarrhea; dehydration, perhaps related, in turn, to the “decreased thirst sensation” many elderly people experience; and kidney disease.

Hyponatremia also can be caused by medications that include such over-the-counter anti-inflammatories as ibuprofen (Advil and Motrin) or naproxen (Aleve), thiazide diuretics and some antidepressants, Jeong says. It also can be caused by cancers or malignancies.

Jeong can’t speak to our reader’s specific cases, but does suggest a visit to a doctor. Then, a cause can be discerned and a possible treatment determined.

In the meantime, Jeong considers it plausible that a surgeon might wish to defer surgery or another sort of medical procedure until a patient’s sodium balance is restored.

A surgeon “obviously wants (a) patient to be in the perfect — or in the most optimal — medical condition for them to do the surgery, because (the patient) is going to be under anesthesia and a lot of stress to the body,” he says.

Given the stresses surgery already places on the body, Jeong says, “surgeons are sometimes reluctant to dive right in to surgery until these things are looked into, and to say, ‘OK, why is it low and is it something reversible?’ ”