When the new coronavirus stormed the Northeast this year, Alan Kliger, a kidney specialist at Yale University, thought it would behave like a typical respiratory virus.
There were signals from China that the new disease was hard on the kidneys, but nephrologists like Kliger were not prepared for what happened when cases broke out in New York. So many patients sustained kidney injury that the liver from dialysis ran short. Two studies of New York patients found that 68% to 76% of intensive care patients with COVID-19 had kidney damage. In one, a third of ICU patients required dialysis, a process in which a machine performs the blood filtering work of the kidney.
“The amount of acute injury and failure was unexpected and dramatic,” said Kliger, co-chair of the American Society of Nephrology’s COVID-19 Response Team.
It is too early to know if survivors of serious COVID-19 have long-lasting kidney damage, but doctors are worried. “People are just waking up to the fact that the kidney is an underrated manifestation (of COVID-19), but one that is quite important,” said Girish Nadkarni, a nephrologist and researcher at Mount Sinai Health System in New York. “There could be an epidemic of post-coronavirus kidney disease.”
The story of Sonia Toure is what Nadkarni is afraid of. Toure, 54, who worked as a research coordinator for City University of New York in the spring, had no chronic health problems before her first symptom of COVID-19 – a single cough – during a Zoom meeting on March 25. Within a day, she had a sore throat and 103-degree fever, but no trouble breathing. The next few days there was more fever along with aches and pains that would make her feel like a mob had beaten her. For one happy day she thought she was getting better, but on April 7, she knew she had to go to the hospital.
At Mount Sinai, doctors discovered she was in kidney failure and began dialysis. She had pneumonia but never needed a ventilator. After 35 days in hospital, she returned home on May 12 to her two sons, aged 19 and 21, and two German shepherds. The next day a doctor called with the results of her kidney biopsy.
“The doctor said there was absolutely no hope that my kidneys were so damaged that I would never recover,” she said. “I would have to be on dialysis for the rest of my life until I could get a transplant.”
Jia Ng, a nephrologist at Northwell Health in New York, said that even patients recovering from acute kidney injury are at higher risk of later developing chronic disease.
“Chronic kidney disease is already a major problem for the country, costing us billions,” Nadkarni said. He is co-researcher of a new study examining the long-term prognosis for coronavirus patients who have kidney damage, as well as how it prevents damage. The study will include researchers from Rutgers University, Yale, and other major medical centers.
Currently, Kliger said, half a million Americans are on dialysis, a process that requires most patients to be connected to a machine for four hours a day, three days a week. About 100,000 new people start dialysis each year, while another 100,000 stop because they are dying.
An important question is whether coronavirus causes a net increase in dialysis patients. It remains to be seen how deaths of people already on dialysis who catch COVID-19 will balance new dialysis patients, doctors would say. Fresenius Medical Care North America and DaVita Kidney Care, the nation’s two largest dialysis providers, did not answer questions about whether demand for dialysis has increased.
It is also unclear whether COVID-19 will lead to an increase in demand for kidney transplants. Kliger said his health system encourages virtually all patients with permanent kidney failure and dialysis to consider transplantation.
While dialysis keeps people alive, it does not bring them back to normal. “A 30-year-old on dialysis will have (almost) the same life expectancy as a 55-year-old who is not on dialysis,” Kliger said.
People who already have damaged kidneys have the greatest risk of more injury than hospitalized for COVID, but 70% of kidney injuries at Mount Sinai were in people not previously known to have kidney disease, Nadkarni said. Diabetes, high blood pressure, fascial disease, old age, and black as Spanish increase the risk of kidney problems.
Hospitalization was always hard on kidneys
Even before COVID-19 hit, hospitalization – particularly an ICU stay – increased the risk of acute kidney injury. Normally, 22.7% of hospitalized patients have acute kidney injury, Ng said. However, only about 4% are in stage 3, the most serious. Studies showed rates of kidney injury ranged from 60% to 78% for ICU patients for COVID. During COVID emergence, 37% of Northwell’s COVID-19 patients, including 90% of those on ventilators, had kidney injuries. Almost a third of those had stage 3 disease. Thirty-five percent of COVID-19 patients with kidney injury had died when a study was published in May.
A Mount Sinai study of 3,235 patients hospitalized for COVID-19 between February 27 and April 15 found that 46% had acute kidney injury with 20% requiring dialysis. Forty-five% had stage 3 disease. About a third of those in the ICU needed dialysis. The mortality rate for those with acute kidney injury was generally 41% and 52% for ICU patients. Fifty-six percent of those who were discharged alive had regained their kidney function.
There are no studies yet on whether kidney function is affected by coronavirus infection that does not lead to a hospital stay.
Nephrologists at Penn, Jefferson, and Temple Health said they had not yet analyzed their patient data in detail. Although it was difficult to provide a large influx of very sick patients who needed isolation, they said their hospitals did not lack dialysis transport. Dan Negoianu, a critical care nephrologist at Penn Medicine, said Penn’s numbers are in line with those of New York. Omar Maarouf, a nephrologist who directs the Jefferson Unit for Acute Dialysis in Philadelphia, said about 20% of Jefferson’s coronavirus patients had kidney injuries and 10% of those who needed dialysis. Suzanne Boyle, a nephrologist at the temple, said she could not share statistics but her hospital had a “high volume” of dialysis patients during the COVID-19 surgery.
Paul Palevsky, a nephrologist at the University of Pittsburgh Medical Center and incoming president of the National Kidney Foundation, said there is anecdotal evidence that kidney injury has put less stress on health systems in hot spots outside New York that take more time. had to prepare. Data from the south and west are missing. It is possible, doctors said, that improvements in COVID-19 treatment will reduce kidney damage.
Doctors are not sure why the kidneys are so vulnerable. One reason is that many hospitals COVID-19 patients are extremely ill, and that is difficult for the kidneys. “Critically ill COVID patients are incredibly ill,” Negoianu said. The kidneys need strong blood flow, but the flow decreases when patients are dehydrated or have low blood pressure. Fever, nausea and diarrhea can lead to dehydration.
Early in the pandemic, many patients may be afraid to go to the hospital, Ng said. “We saw a large number of patients who were very dry,” she said. Maintaining blood pressure is a challenge for people with breathing problems.
The inflammation that comes with disease and intense immune response can further weaken the kidneys.
Doctors said the kidneys suffered along with the rest of the body. “The kidney is sometimes an innocent bystander,” Boyle said. “When things are not going well with the rest of the body, the kidneys feel it too.”
Whether the coronavirus directly attacks kidney cells is controversial. Some studies find no sign of the virus in kidney tissue, but a recent Lancet study found viral RNA in 60% of 63 autopsy tests and in 72% of samples from patients with acute kidney injury.
Another possibility, Negoianu said, is that blood clotting caused by COVID-19 damages kidneys.
Genetics can also play a part. APOL1 genetic variants are linked to a higher incidence of kidney disease in people of African descent and are associated with kidney injury with other viruses, including HIV, Palevsky said. Nadkarni is investigating whether the genetic variant, found in 1 in 7 African Americans and 1 in 20 Latinos with Caribbean ancestry, may also affect how humans respond to the coronavirus.
Whatever causes the damage, the kidneys stop doing their job. Toxins build up in the body. Palevsky said that can cause confusion, even coma. The kidneys are also responsible for getting rid of salt and excess fluid. If they do not work properly, fluid can build up in the lungs and cause shortness of breath. Higher potassium levels can cause severe and fatal heart rhythm problems.
