The presence of blood in the urine, known as hematuria, is not a primary symptom of COVID-19. However, it has been observed in some patients, particularly those with more severe infections. Hematuria can signal that the virus may be affecting organs beyond the lungs. Reports from early in the pandemic noted that a percentage of hospitalized individuals showed signs of hematuria, prompting investigation into the virus’s effect on the urinary system.
How COVID-19 Affects the Kidneys
The SARS-CoV-2 virus can affect the kidneys through several mechanisms, leading to hematuria. One primary pathway is direct viral infection of kidney cells. The kidneys have cells with angiotensin-converting enzyme 2 (ACE2) receptors on their surface, which the virus uses as a gateway to enter and replicate, causing direct injury to kidney tissues.
Another significant factor is the body’s immune response. In some individuals, the immune system can become overactive, leading to a “cytokine storm.” This massive release of inflammatory molecules can cause widespread damage to organs, including the kidneys. This inflammation can injure the small blood vessels within the kidneys, impairing their function and causing blood to leak into the urine.
COVID-19 also increases the risk of blood clot formation. Tiny clots, or microthrombi, can develop in the smallest blood vessels of the kidneys. These clots block blood flow, depriving kidney tissue of oxygen and leading to damage. This process can contribute to acute kidney injury (AKI), a sudden decline in kidney function that is a serious complication of severe COVID-19.
Visible and Microscopic Blood in Urine
Hematuria can present in two distinct forms: gross hematuria and microscopic hematuria. Gross hematuria is when the blood is visible to the naked eye, causing urine to appear pink, red, or brownish like cola. This discoloration is caused by a sufficient number of red blood cells being present to alter the urine’s color.
In contrast, microscopic hematuria is not visible and can only be detected through laboratory testing of a urine sample, a procedure known as urinalysis. Even if the urine appears normal, it may still contain a higher-than-normal number of red blood cells, indicating some level of kidney or urinary tract injury. Healthcare providers may test for microscopic hematuria if other signs of kidney stress are present.
When to Contact a Doctor
Any instance of visible blood in the urine warrants a conversation with a healthcare provider, as it can point to issues like infections, kidney stones, or urinary tract injury. Seeking a prompt medical evaluation is the best way to determine the cause.
Certain symptoms alongside hematuria signal a need for more urgent medical attention. Contact a doctor immediately if you notice blood in your urine accompanied by:
- A significant decrease in urination
- Swelling in the legs, ankles, or feet
- New or worsening fatigue
- Shortness of breath
- A sense of confusion
These symptoms could indicate acute kidney injury or other complications that require prompt intervention.
Diagnosis and Treatment Approaches
When a patient presents with hematuria, a doctor will begin an evaluation to identify the underlying cause. This process starts with a review of the patient’s medical history and a physical examination. A urinalysis is a standard step to confirm the presence of blood, check for signs of infection, and measure protein levels, which can also indicate kidney stress. Blood tests are also common to assess kidney function, and imaging tests like a kidney ultrasound may be ordered to view the urinary tract.
Treatment for hematuria associated with COVID-19 focuses on managing the root cause rather than the symptom itself. The primary goal is to treat the viral infection and provide supportive care to the kidneys. This may involve managing fluid intake, monitoring blood pressure, and discontinuing any medications that could harm the kidneys. If kidney function is severely impaired, more advanced supportive measures may be necessary.