COVID-19 — the disease caused by the coronavirus that’s led to the global pandemic —is known to damage the lungs. But, as more people become infected, more understanding of the disease emerges.
Doctors and researchers are finding that this coronavirus — officially called SARS-CoV-2—can also cause severe and lasting harm in other organs, including the heart and kidneys. C. John Sperati, M.D., M.H.S., an expert in kidney health, discusses how the new coronavirus might affect kidney function as the illness develops and afterward as a person recovers.
Some people suffering with severe cases of COVID-19 are showing signs of kidney damage, even those who had no underlying kidney problems before they were infected with the coronavirus. Early reports say that up to 30% of patients hospitalized with COVID-19 in China and New York developed moderate or severe kidney injury. Reports from doctors in New York are saying the percentage could be higher.
Signs of kidney problems in patients with COVID-19 include high levels of protein in the urine and abnormal blood work.
The kidney damage is, in some cases, severe enough to require dialysis. Some hospitals experiencing surges of patients who are very ill with COVID-19 have reported they are running short on the machines and sterile fluids needed to perform these kidney procedures.
“Many patients with severe COVID-19 are those with co-existing, chronic conditions, including high blood pressure and diabetes. Both of these increase the risk of kidney disease,” Sperati says.
But Sperati and other doctors are also seeing kidney damage in people who did not have kidney problems before they got infected with the virus.
The impact of COVID-19 on the kidneys isn’t yet clear. Here are some possibilities doctors and researchers are exploring:
The virus itself infects the cells of the kidney. Kidney cells have receptors that enable the new coronavirus to attach to them, invade, and make copies of itself, potentially damaging those tissues. Similar receptors are found on cells of the lungs and heart, where the new coronavirus has been shown to cause injury.
Another possibility is that kidney problems in patients with the coronavirus are due to abnormally low levels of oxygen in the blood, a result of the pneumonia commonly seen in severe cases of the disease.
The body’s reaction to the infection may be responsible as well. The immune response to the new coronavirus can be extreme in some people, leading to what is called a cytokine storm.
When that happens, the immune system sends a rush of cytokines into the body. Cytokines are small proteins that help the cells communicate as the immune system fights an infection. But this sudden, large influx of cytokines can cause severe inflammation. In trying to kill the invading virus, this inflammatory reaction can destroy healthy tissue, including that of the kidneys.
The kidneys are like filters that screen out toxins, extra water and waste products from the body. COVID-19 can cause tiny clots to form in the bloodstream, which can clog the smallest blood vessels in the kidney and impair its function.