Hyponatremia from a Nephrologist's Perspective

Anil Asgaonkar, MD, a nephrologist with Star Nephrology in Denton, TX, provides a basic overview of the signs, symptoms, and causes frequently associated with hyponatremia, and outlines several standard treatment approaches.

“Typically when I see hyponatremia some of the early mild symptoms are nausea, confusion such as difficulty finding words, forgetfulness, and as it worsens, gait disturbances. With severe hyponatremia sometimes I see seizures,” Asgaonkar said.

Certain groups are more at risk for hyponatremia, including “the elderly ‘tea and toast’ types who eat very little and drink a normal amount of water so they get less salt in their diet. Also, patients with significant heart failure, as they secrete a hormone that makes them reabsorb more water than salt which leads to hyponatremia,” Asgaonkar said.

Hyponatremia can be caused by “anything that causes salt and water to go out of balance, but the main causes are heart failure or liver disease, in which case patients end up swollen with too much water or salt.” Asgaonkar also noted that patients who are on diuretics can become dehydrated and “loose more salt than water, so their water balance is still too high for the amount of salt.” He said there are also individuals who have “normal amounts of salt and water fluid balance, but they have a syndrome of anti-diuretic hormones like thiazide, so there is too much ADH released. This can be related to different medications people are on or medical conditions like low thyroid.”

Hyponatremia is a serious issue because it severely impacts a patient’s quality of life. The symptoms are insidious, but they impact everyday functioning. “Nobody wants to feel confused or as though they can’t walk well. Nobody wants a seizure. These are significant types of symptoms,” Asgaonkar said.

There are many forms of treatment that are conservative and help stabilize sodium levels. The testing process is easy and involves blood and urine work. Getting the results to those tests can make a big difference in treatment selection.

“Typically we restrict how much water people take because hyponatremia is too little salt in relation to the total amount of water in the body. We have to work on both increasing salt and decreasing the total amount of water in the body. We limit people to drinking a quart of fluid a day. Depending on the cause of the hyponatremia, we can add some diuretics that help excrete water as well as some salt tablets. If we have to, we use ADH antagonists. They are an expensive treatment that came out a few years ago,” said Asgaonkar.

Hyponatremia is difficult to manage because the brain has protection mechanisms for salt and water transfer. If the sodium level drops over a significant period of time the level has to be raised slowly so it doesn’t precipitate swelling in the brain. Occasionally, the treatment of hyponatremia can cause death. Most nephrologists follow well-described and strict protocols to ensure the sodium level goes up slowly over time. They check blood work every 2-4 hours and are cautious about increasing the sodium level.

“This is a fairly common condition that I see frequently. I think it’s becoming more common because of the variety of medicine people are on, the aging of our population, and the incidence of congestive heart failure,” said Asgaonkar.

Bridget Barry Thias is a Dallas-based freelance writer.