En español | While initially the most feared complication of COVID-19, the illness caused by the new coronavirus, was respiratory failure, studies now show that many other organs, including the kidneys, can be affected by the viral infection, too. In some cases, the virus has caused acute kidney damage.
Alan Kliger, M.D., clinical professor of medicine at Yale University School of Medicine and cochair of the COVID-19 response group for the American Society of Nephrology, says that those most at risk for acute kidney injury with a COVID-19 infection are people with diabetes, high blood pressure and chronic kidney disease.
"The most important message overall is that for these particularly vulnerable populations, testing patients for symptoms of disease and tracking their contacts is critically important. It's something we have not adequately been able to do in the U.S.,” he says.
While experts don't yet know how many COVID-19 patients with acute kidney injuries will suffer permanent damage — or recover part or all their kidney function — they're beginning to learn the ways that the stealthy virus can sneak up on this organ.
How the virus harms the kidneys
When COVID-19 first enters the body, it can trigger a generalized immune response that releases proteins called cytokines, which cause a storm of cell, organ and tissue damage.
The virus can also directly force its way into the kidney by binding directly to kidney receptors, as reported in the Journal of the International Society of Nephrology last month. Researchers found clusters of the virus in the kidneys as well the urine of 9 out of 26 patients in Wuhan, China, who died from COVID-19.
Also, since the lungs and the kidneys depend on each other to function, there is “organ crosstalk” between them that can lead to damage in the kidneys, according to a study published last month in Nature Reviews Nephrology.
In a COVID-19 or any patient, the consequences of an acute kidney injury can be severe. For a critically ill patient in the intensive care unit who develops one, for instance, the risk of death is somewhere between 40 to 70 percent, says Paul Palevsky, M.D., president-elect of the National Kidney Foundation and professor of medicine at the University of Pittsburgh School of Medicine.
"We don't really know the mortality rate of patients with a COVID-19 infection and acute kidney failure. Some reports have been as high of a mortality rate of 90 percent. It's too early to know,” he says.
As for how many patients will develop kidney injury from COVID-19? Initial reports from China, where the COVID-19 virus first began, suggested a fairly low rate, of around 5 percent of total cases, says Palevsky. However, new data from Italy and New York City suggest a much higher rate of kidney injury from the virus. “It's possibly as high as 25 to 40 percent among the sickest hospitalized patients in the intensive care unit. The sicker the patient, the more severe the kidney involvement,” he says.
In the most extreme cases, patients who go into acute renal failure lose their ability to remove waste and balance fluids in the body, and need dialysis or mechanical purification of their blood.
Doctors know how to treat the problem, but circumstances are getting in the way.
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Dialysis shortages in some areas
"I think everyone has read in the news about the fear of not having enough ventilators and needing to triage patients as to who gets a ventilator and who would not. In fact, the same problem is happening with our ability to provide dialysis in areas that have seen a surge of patients needing them, such as in New York City,” says Palevsky.
These shortages have presented major challenges to patient care, he notes. There are more patients than machines for dialysis, as well as shortages of materials needed for performing dialysis, including disposable tubing and fluids. Usually one machine is used to treat patients with acute renal failure continuously for 24 hours a day for as long as a patient needs that therapy.
Some hospitals experiencing equipment shortages are now treating patients on a 24-hour-on, 24-hour-off basis, so they are able to treat twice as many patients with the same number of machines. Hospitals in areas that are past a COVID-19 surge also are trading dialysis equipment with those in the thick of the outbreak.
While dialysis shortages present an urgent problem in certain areas, there is hope on the horizon for reducing the risk of organ damage by COVID-19, says Hamid Rabb, M.D., professor of medicine and medical director of kidney transplantation at Johns Hopkins University.
At Johns Hopkins, for instance, “there are many different trials currently underway to decrease the abnormal hyperinflammatory response of COVID-19,” Rabb says. “Some of the initial studies are very promising. I hope that in a few weeks we will have a better idea of how these trials are working."