The COVID-19 pandemic, caused by the SARS-CoV-2 virus, has affected millions globally, extending its impact beyond the respiratory system. A common concern involves its potential effects on kidney health. Research confirms a notable link between COVID-19 infection and kidney involvement, ranging from temporary dysfunction to significant damage. This understanding is continuously evolving as scientists gather more data.
How COVID-19 Affects Kidneys
COVID-19 can impact the kidneys through several complex mechanisms, often leading to acute kidney injury (AKI), a sudden decline in kidney function. One way is through direct viral invasion, as SARS-CoV-2 can bind to angiotensin-converting enzyme 2 (ACE2) receptors present on kidney cells, specifically podocytes and proximal tubular cells. This direct binding can cause cellular damage, including acute tubular necrosis and collapsing glomerulopathy, a severe form of kidney damage.
The body’s immune response to the virus also plays a large role in kidney injury. An overactive immune response, often termed a “cytokine storm,” releases a flood of inflammatory proteins that can cause widespread inflammation and damage to kidney tissue. This systemic inflammation can lead to endothelial dysfunction and promote the formation of microthrombi, which can obstruct blood flow and cause ischemic injury to the kidneys. Additionally, indirect effects such as severe dehydration, low oxygen delivery to the kidneys (hypoxia), or drug-induced injury from medications used during treatment can further contribute to AKI in COVID-19 patients.
Recognizing Kidney Issues
Identifying signs of kidney involvement during or after a COVID-19 infection is important for timely medical intervention. One of the most common indicators is a reduced urine output, although sometimes urine production may remain unchanged despite kidney damage. Swelling in the legs, ankles, or feet can also occur due to fluid accumulation.
Individuals might also experience generalized symptoms such as unusual tiredness, nausea, and shortness of breath. In more severe cases, confusion, an irregular pulse, or chest discomfort could signal significant kidney problems. High levels of protein or blood in the urine are also specific indicators of kidney damage.
Who is Most at Risk?
Certain individuals face a higher risk of developing kidney complications from COVID-19 due to underlying health conditions. People with pre-existing chronic kidney disease (CKD) are particularly vulnerable, as their kidneys may already have reduced function, making them less resilient to the additional stress of a viral infection. For instance, patients with end-stage renal disease have been found to be 11 times more likely to be hospitalized with COVID-19 compared to those without kidney disease.
Individuals with diabetes are also at increased risk, as high blood sugar levels can damage blood vessels, including those in the kidneys, making them more susceptible to COVID-19-related injury. Similarly, those with high blood pressure and heart disease may experience worsened kidney outcomes due to the interconnectedness of the cardiovascular and renal systems. Older adults have a higher risk of severe COVID-19 outcomes, including kidney complications, due to age and a higher likelihood of co-existing health conditions.
Long-Term Kidney Implications
Even after recovering from the acute phase of COVID-19, some individuals may experience lasting effects on their kidney health. Research indicates that a significant portion of patients who developed acute kidney injury (AKI) during their COVID-19 illness continue to have reduced kidney function upon hospital discharge. This persistent decline can manifest as new or worsened kidney dysfunction, potentially leading to the development of chronic kidney disease (CKD) over time.
Studies have shown that individuals hospitalized with COVID-19, particularly those who experienced AKI, may have a faster rate of decline in their estimated glomerular filtration rate (eGFR) compared to those with AKI from other causes. For instance, one study reported that 35% of patients discharged after COVID-19 had a progressive decline in kidney function at six months, with their eGFR falling below 90 mL/min. This suggests that ongoing monitoring and follow-up care with a kidney specialist are beneficial for individuals who experienced kidney involvement during their COVID-19 infection, even if their symptoms were initially mild.