Kidney Damage Another Consequence of 'Long COVID'

THURSDAY, Sept. 2, 2021 (HealthDay News) -- People hospitalized for COVID-19, and even some with milder cases, may suffer lasting damage to their kidneys, new research finds.

More than 1.7million COVID patients were studied by the U.S. Veterans Affairs System. These findings raise concerns over the long-term effects of COVID, especially among those with serious illnesses that require hospitalization.

COVID victims were more likely to develop kidney problems months later than they had been initially infected. These ranged from impaired kidney function to severe kidney failure.

The highest likelihood of kidney disease was seen in those who had been the most seriously ill, requiring ICU treatment.

The risk of kidney disease in COVID patients was higher than those who didn't have any obvious kidney problems.

The striking thing is, however, that the latter were still at risk, according to Dr. F. Perry Wilson (a kidney specialist) who wasn't involved in this study.

Their risk of developing kidney dysfunction or other diseases was still approximately two-to five times higher than VA patients without COVID.

Wilson, an associate Professor at Yale School of Medicine in New Haven (Conn), said that despite not having acute kidney damage, patients are still susceptible to developing these problems.

Wilson says there is still some doubt about whether the kidney issues are caused by COVID or if they were brought on board while the patient was sick. For example, it's not clear how patients admitted for flu symptoms would fare in comparison to their kidney function.

The study showed that COVID patients, even those who had been ill at home, were more likely to develop kidney problems.

Could it be inflammation?

Senior researcher Dr. Ziyad Aly from Washington University School of Medicine, St. Louis, said that there were "risks, although smaller," among the patients.

Wilson said that the question "biggest" is: Why?

"Is this reflecting some ongoing immune system stimulation and inflammation?" He said. He said, "It will be more research to figure this out."

The findings -- published Sept. 1 in the Journal of the American Society of Nephrology -- are based on medical records from more than 1.7 million VA patients. The study included 89,216 people who were found to have COVID and they were still alive thirty days later.

This study examined the risk that patients would develop various kidney conditions in the following 30 days.

COVID sufferers were significantly more likely to experience a drop in kidney glomerularfiltration rate (GFR), which measures how efficient the organs filter out waste from the blood.

The study revealed that just over 5% had GFR drops of 30 percent or greater in COVID patients. Their risk of developing COVID was also 25% greater than that of the general VA population.

Wilson says that a decline of 30% in GFR, which is about the equivalent of losing 30 years' worth of kidney function each year, would be natural for adults who lose approximately 1% of their kidney functions per annum.

Study also looked at the possibility of severe kidney injury. This is when the organs lose their function suddenly. It can cause symptoms such as swelling in the legs, fatigue and breathing difficulty, but sometimes causes no overt problems.

Patients with COVID were twice as likely to suffer from acute kidney injury than those without it. However, this varied depending on the severity of their COVID.

What will be the effect on kidney function?

The risk of developing acute kidney injury in patients who were hospitalized was five to eight times higher than that for non-COVID patients. People who have been sick at their home with COVID are 30% more likely to experience this condition.

Al-Aly stated that it is not known how this affects COVID patients' kidney health in the long-term.

He said that it is unclear if the GFR will decline in certain patients.

Wilson stated that acute kidney injury can be treated and people will recover with minimal long-term harm. He also noted that GFR may rise if acute kidney injury is involved.

Some patients in the study did develop end-stage kidney failure. These odds were highest among COVID patients, who had been admitted to the ICU. They experienced the disease at an average rate of 21 cases per 1000 patients each year. This makes their chance 13 times greater than that of other VA patients. There were lower risks for COVID patients who had not been admitted to hospital.

One limitation to the study was that VA patients were mostly older males. Al-Aly said that it's not clear how the findings can be extended.

It is also unclear what the risks are for non-hospitalized patients. Both doctors stated that they are not a homogenous group.

Wilson believes that those only moderately affected with COVID will not develop any kidney problems. However, people who have been "really sick for weeks" may be at greater risk.

Al-Aly stated that basic blood tests can detect kidney dysfunction at routine primary care visits.

Wilson suggested that this type of test might prove worthwhile for those who are more severe with COVID.

More information

The National Kidney Foundation has more on COVID-19 and kidney disease.

SOURCES: Ziyad Al-Aly, MD, assistant professor, medicine, Washington University School of Medicine in St. Louis; F. Perry Wilson, MD, associate professor, medicine, Yale School of Medicine, New Haven, Conn.; Journal of the American Society of Nephrology, online, Sept. 1, 2021