COVID-19 impairs the kidneys' ability to filter waste and toxic substances in some patients, a new report suggests.
Kidney filters do not usually allow much protein into the urine. Researchers who studied 103 COVID-19 patients found that about 24% of them had high levels of the protein albumin in their urine, and 21% had high levels of the protein cystatin c in their urine.
About 25% of the patients had a noninfectious piece of the coronavirus in their urine, but none of the samples contained infectious virus.
That suggests the virus particles researchers did see were "a direct result of a filtration abnormality rather than a viral infection of the kidney," according to a report posted on Sunday on medRxiv ahead of peer review.
None of the patients had signs of kidney dysfunction, other than the filtration issues.
"At this stage, we do not know whether or not these abnormalities are a sign of long-term consequences," said coauthor Choukri Ben Mamoun of the Yale School of Medicine. "It is for this reason that we report these findings and emphasize the need for long-term examination of the consequences of this infection."