COVID-19 doesn’t just affect the lungs—it can also harm your kidneys and cause a condition called anemia, where your body doesn’t have enough healthy red blood cells. This is especially dangerous for people who already have kidney disease. Researchers reviewed studies to understand how COVID-19 damages kidneys and why people with existing kidney problems get sicker from COVID-19. They found that the virus affects kidneys through multiple pathways, and people with kidney disease who get COVID-19 often develop anemia that’s harder to treat. Understanding these connections helps doctors better care for patients with both conditions.

The Quick Take

  • What they studied: How COVID-19 affects the kidneys and causes anemia (low red blood cells), especially in people who already have kidney disease
  • Who participated: This was a review of 19 published studies, not a direct study of patients. It combined findings from research about COVID-19, kidney disease, and anemia
  • Key finding: People with existing kidney disease who get COVID-19 are at much higher risk of serious illness and death. They’re also more likely to develop anemia that doesn’t respond well to standard treatments
  • What it means for you: If you have kidney disease, protecting yourself from COVID-19 is especially important. Talk to your doctor about your specific risk and what precautions make sense for you

The Research Details

This was a literature review, meaning researchers read and analyzed 19 published scientific studies about COVID-19, kidney damage, and anemia. They looked for patterns and connections between these conditions to better understand how they relate to each other.

The researchers focused on understanding the biological mechanisms—the ways the virus actually damages kidney cells and interferes with the body’s ability to make healthy red blood cells. They examined how COVID-19 enters and damages kidney tissue, and how this damage leads to anemia.

This type of review helps scientists and doctors see the bigger picture by combining information from many different studies, rather than looking at just one study alone.

A review like this is valuable because it helps doctors understand complex relationships between diseases. By combining findings from multiple studies, researchers can identify patterns that might not be obvious from a single study. This helps doctors predict which patients are at highest risk and how to treat them better.

This is a review article, which means it summarizes existing research rather than conducting a new study. The strength of the conclusions depends on the quality of the 19 studies reviewed. The researchers were looking at published, peer-reviewed studies, which is good. However, this type of review is considered lower-level evidence than a new research study with direct patient data. The findings suggest connections but don’t prove cause-and-effect relationships.

What the Results Show

The research shows that COVID-19 can damage kidneys through several different biological pathways. The virus affects special proteins in kidney cells that normally help regulate blood pressure and fluid balance. When these proteins are disrupted, the kidneys can’t work properly.

People with existing chronic kidney disease (CKD) who get COVID-19 face much worse outcomes. They have higher rates of hospitalization in intensive care units and higher death rates compared to COVID-19 patients without kidney disease.

Anemia—not having enough healthy red blood cells—is very common in people with kidney disease and becomes even worse when they get COVID-19. The virus appears to make the body resistant to a medication called erythropoietin (EPO), which normally helps create red blood cells. This means patients need higher doses of this medication, sometimes for months after recovering from COVID-19.

The research identified multiple factors that contribute to anemia in COVID-19 patients with kidney disease: reduced production of EPO, damage to blood vessels in the kidneys, iron deficiency, bleeding problems, inflammation, and shortened lifespan of red blood cells.

The studies showed that COVID-19 patients with kidney disease have significantly elevated levels of certain blood markers that indicate severe illness: D-dimers (a clotting marker), inflammatory proteins, creatinine, and blood urea nitrogen (waste products that kidneys normally filter out). These elevated markers suggest the virus causes widespread damage throughout the body.

The research also found that a protein called hepcidin becomes overproduced in these patients. Hepcidin controls how the body absorbs and uses iron, and when it’s overproduced, it prevents the body from using iron effectively to make new red blood cells. This creates a vicious cycle where patients can’t make enough healthy blood cells even if they have adequate iron intake.

This review builds on earlier observations that COVID-19 affects multiple organ systems beyond the lungs. Previous research had shown kidney involvement in COVID-19, but this review specifically connects kidney damage to anemia development and explains the biological mechanisms. The findings align with what doctors have observed clinically—that patients with pre-existing kidney disease have worse COVID-19 outcomes—and now provides scientific explanation for why this happens.

This is a review of existing studies, not original research with patients. The conclusions are based on what other researchers have published, so the quality depends on those studies. The review doesn’t provide new data about how many people are actually affected or how common these complications are. Additionally, COVID-19 is still relatively new, so some long-term effects may not yet be fully understood. The review focuses on mechanisms but doesn’t provide clear guidance on how to prevent or treat these complications in practice.

The Bottom Line

If you have chronic kidney disease, take extra precautions to avoid COVID-19 infection (vaccination, masking in high-risk settings, avoiding crowds during surges). If you do get COVID-19, seek medical care promptly and inform your doctor about your kidney disease. Work with your healthcare team to monitor your kidney function and blood counts closely during and after COVID-19 infection. If you develop anemia symptoms (fatigue, shortness of breath, weakness), report them immediately to your doctor. These recommendations are based on solid evidence from multiple studies.

This research is most important for people with chronic kidney disease of any stage. It’s also relevant for people on dialysis, those who have had kidney transplants, and older adults with multiple health conditions. Healthcare providers caring for these populations should use this information to identify high-risk patients and provide closer monitoring. People without kidney disease should still protect themselves from COVID-19, but this research doesn’t change general prevention recommendations for the general population.

If you get COVID-19 with existing kidney disease, problems can develop within days to weeks. Anemia may persist for months after the acute infection resolves. Recovery depends on the severity of kidney damage and individual factors. Some people recover kidney function completely, while others experience lasting damage. This is why ongoing monitoring is important.

Want to Apply This Research?

  • If you have kidney disease, track your energy levels daily (1-10 scale) and note any shortness of breath, dizziness, or unusual fatigue. Also log any COVID-19 symptoms immediately. This helps you and your doctor spot anemia or worsening kidney function early.
  • Set reminders to take any prescribed kidney or anemia medications exactly as directed. If you have kidney disease, prioritize COVID-19 vaccination and boosters. Log any new symptoms or changes in how you feel to discuss with your doctor at appointments.
  • If you have kidney disease, establish a baseline of your normal energy and symptoms. Use the app to track changes over time. Set alerts for important lab test dates (kidney function tests, blood counts). If you get COVID-19, increase monitoring frequency to daily check-ins on symptoms and energy levels for at least 4 weeks after infection.

This review summarizes scientific research but is not medical advice. If you have kidney disease or have had COVID-19, consult your healthcare provider about your individual risk and what monitoring or treatment is appropriate for you. Do not change any medications or treatments based on this information without talking to your doctor first. This research describes potential complications but doesn’t mean everyone with kidney disease who gets COVID-19 will experience these problems. Your doctor can assess your specific situation and provide personalized recommendations.