Soaring — or Sinking? — Sodium

Out-of-whack sodium levels — whether too high or too low — can throw off many health functions, from balance to cognition.

It’s hard to miss the warnings about high sodium. Health magazines rail against it in processed food, and restaurants routinely provide reduced-sodium soy sauces. But low sodium levels can be a problem, too — an issue that’s tougher to spot and harder to treat.

Sodium is an electrically charged mineral called an electrolyte. It helps the body function, controlling fluid levels and pH balance. If you take in too much sodium from the foods you eat, your kidneys secrete the extra through your urine.

Normal sodium levels in the blood range from 135 to 145 milliequivalents per liter. Levels outside of that tight span may mean dehydration, kidney issues, or other medical conditions.

Jay Paparello, MD, nephrologist and sodium expert at Northwestern Medicine, says that high sodium levels in the blood typically mean that a person is not consuming enough water.

Symptoms of high sodium include:

  • Confusion
  • Diarrhea
  • Infrequent urination
  • Muscle twitches
  • Nausea
  • Seizures
  • Thirst

Infants through centenarians can experience high sodium. “Most of the time, people who come in with high sodium levels are either an older person in a nursing home or a young baby who can’t tell you that they’re thirsty and that they need water,” Paparello says.

Rakhi Khanna, DO, nephrologist at RUSH University Medical Center, says that in situations where people rely on others for food and water, they could suffer from high sodium because they can’t act on that thirst themselves. “But in the case of most people, our thirst mechanism is so good that your mouth will feel parched, and you’ll want to drink water.”

Low sodium is more difficult to treat. It is also more common and more concerning.

Symptoms of low sodium are similar to high sodium symptoms and include:

  • Confusions
  • Fatigue
  • Headaches
  • Muscle twitches
  • Nausea
  • Seizures
  • Weakness

“A low-sodium problem is related to a water imbalance in the blood, and we try to figure out what is causing it,” Khanna says.

Low sodium levels affect balance, which can lead to falls — a major concern for older adults.

“A lot of people think that if their sodium’s low, just eat salt. But it’s figuring out why the body is holding onto water,” Paparello says.

In some cases, older people don’t eat enough protein, and they drink too much water. “We call it the tea-and-toast diet, as they aren’t eating the more substantial food that they should be eating,” Paparello says.

Medications can also cause low-sodium levels, which is why people who are being treated for cancer with chemotherapy or immunotherapy need to have their sodium levels monitored, Khanna says.

Other causes include some medications for high blood pressure, a thyroid hormone imbalance, and dehydration from vomiting or diarrhea. Heart disease can also be a culprit.

In treating too-high or too-low sodium levels, doctors need a very detailed medical history. Treatment sometimes requires dietary changes, but medication changes also may be necessary.

“If they need to make changes, gradual changes are the best way to go,” Paparello says.

Ultimately, though, Khanna says, whether sodium levels are too high or too low, “There can be an underlying condition that’s causing it, and we need to look for it.”