Sodium Levels Predict Risk of COVID-19 Complications: Study

Patients hospitalized with COVID-19 may have a poorer prognosis if they have abnormal sodium levels, according to a new study in The Journal of Clinical Endocrinology & Metabolism.

“This study shows for the first time that patients presenting at the hospital with COVID-19 and low sodium are twice as likely to need intubation or other means of advanced breathing support as those with normal sodium,” said Ploutarchos Tzoulis, MD, PhD, MSc, Honorary Associate Professor in Endocrinology at University College London (UCL) Medical School, in a press release for The Endocrine Society.

The authors of the study suggest that looking at sodium levels could help healthcare providers identify which COVID-19 patients are at the most risk for poor outcomes.

How Does COVID-19 Change Sodium Levels?

Nitin Desai, MD, CEO and CMO of COVID PreCheck, says that a balance of sodium and water is needed to maintain a healthy body. Usually, the body’s sodium levels are regulated by the antidiuretic hormone vasopressin, which is released from the posterior pituitary gland in the brain. Antidiuretic hormones help control the amount of water being filtered out through the kidneys.

There is evidence that a COVID-19 infection could disrupt this process. According to Javeed Siddiqui MD, MPH, Chief Medical Officer at TeleMed2U, about 30% of individuals experience low sodium levels when experiencing pneumonia.  

Low sodium levels can cause a condition called syndrome of inappropriate antidiuretic hormone secretion (SIADH), where an inappropriate amount of antidiuretic hormone is released in the body. SIADH is commonly observed in patients in the hospital with pneumonia.

Some research has suggested that coronavirus-induced pneumonia is linked to low sodium levels:

• A June 2020 study in Cureus documented a case of a hospitalized patient that had hyponatremia from pneumonia during a COVID-19 infection. The patient was later diagnosed with SIADH.
• Another study, which was also published in June 2020 in the journal Endocrinology and Metabolism, reported three cases of COVID-19 patients ranging in age from 20 to 58 years old who had fever, pneumonia, and severe hyponatremia.

Desai says that about one-third of hospitalized patients for COVID-19 will have low sodium levels. COVID-induced pneumonia that causes SIADH could be triggered by an immunological condition. He suggests that interleukin-6 (a cytokine associated with increased inflammation in COVID-19 infection) could be the culprit.

Siddiqui agrees, adding that the “increase in cytokines can result in SIADH via IL-6 directly stimulating the nonosmotic release of [anti-diuretic hormones] or due to injury of lung tissue and alveolar cells, which can induce SIADH via the hypoxic pulmonary vasoconstriction pathway.”

Collecting Research Data

For the new study, the researchers enrolled 488 adults (277 men and 211 women) with a median age of 68 years who had been diagnosed with COVID-19 and were admitted to either the UCL Hospital or the Whittington Hospital between February and May 2020.

The hospital’s total mortality rate was 31.1%, with patients dying at a median of seven days after they were admitted. The patients who survived stayed in the hospital for a median of eight days.

The majority of patients had another chronic medical condition, the most common being hypertension (45.7%), diabetes (25%), and chronic kidney disease (16.4%).

Incidence of Abnormal Sodium Levels

Only 5.3% of patients had high sodium levels when they were admitted to the hospital compared to 24.6% of patients who arrived with low sodium levels. About 18.4% had mildly low sodium levels, and 6.2% had moderate to severely low sodium levels.

Only 19% of patients showing severely abnormal sodium levels were tested for hyponatremia. Hypovolemic hyponatremia—a condition where the amount of sodium in the body is greater than the total amount of water in the body—was diagnosed in 75% of patients.

Abnormal Sodium Levels Linked to Mortality Rate

The study’s findings showed that high sodium levels were associated with a 46.1% risk of dying in the hospital. This was followed by a 30.8% mortality for patients with low sodium levels. People with normal sodium levels showed a 28.4% mortality risk.

Having high sodium levels in the first five days of hospitalization, being of older age, and having higher C-reactive protein concentrations (a marker for inflammation) were also associated with dying in the hospital.

The researchers also found that having high sodium levels on the third and sixth day of hospitalization was most closely linked to mortality.

Effects of Abnormal Sodium Levels on Hospitalization Stay

The researchers found that sodium and urea levels appeared to increase in all patients during their hospital stay.

High sodium levels increased from 5.3% during hospital admission to 13.8% after five days. The chances of patients having low sodium levels were reduced from 24.6% to 14.1% during this time. The patients whose sodium levels increased while they were in the hospital were more likely to die after five days.

Low Sodium Levels May Predict Respiratory Failure

About 100 patients needed breathing assistance, 51 required a CPAP machine, 25 needed to be placed on a ventilator, and 24 patients needed both devices.

About 31.7% of the patients with low sodium levels needed to be on respiratory ventilators compared to 17.5% of the patients with normal sodium levels and 7.7% of the patients with high sodium levels.

The authors of the study suggest that having low sodium levels is associated with a two-fold increase in needing respiratory support. In the press release, Tzoulis said that “sodium measurements can inform doctors about which COVID-19 patients are at high risk of deterioration and death” and “can guide decision making about whether a COVID-19 patient needs hospital admission or monitoring in the intensive care unit.”

Monitoring Sodium Levels and Reducing Risk

Siddiqui says that any person with COVID-19 is at risk of developing a sodium or electrolyte balance. However, the risk is greater for older people, people with comorbidities, and people who are dehydrated.

Desai says that with regard to COVID-19 treatment, healthcare professionals need to treat the conditions causing SIADH—as most mortality rates from COVID-19 are not related to SIADH but rather from pneumonia and organ failure affecting the lungs, heart, and kidneys.

However, it’s essential for doctors to monitor sodium levels and perform blood testing if a patient is experiencing SIADH symptoms. To manage sodium levels, Siddiqui recommends that people drink water and water with electrolytes to avoid becoming dehydrated.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.