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As the coronavirus pandemic continues, scientists and physicians are finding out more about the devastating effects on the body due to infection with SARS-CoV-2, the virus that causes COVID-19. We already know about how it harms the lungs and the heart, but we are seeing that severe illness with COVID-19 can also harm the kidneys.
What Do the Kidneys Do?
The main job of the kidneys is to maintain the fluid and electrolyte balance in the body by filtering the blood. The kidneys have several other important jobs including, helping to regulate blood pressure, signaling your bone marrow to manufacture more red blood cells when needed, making vitamin D to keep your bones healthy and strong, and controlling the acid/base balance in your body. If the kidneys are damaged, then dialysis (in which a machine filters the blood in place of the kidneys) or kidney transplant may be required.
Functions of the kidneys:
- Filter blood
- Maintain fluid balance
- Maintain electrolyte balance
- Regulate blood pressure
- Signal bone marrow to create more red blood cells
- Make vitamin D
- Control acid/base balance (pH)
Does Coronavirus Attack the Kidneys?
The mechanism by which SARS-CoV-2 maybe be affecting the kidneys is not well-understood at this point, but there are several hypotheses (which are very similar to the hypotheses regarding how COVID affects the heart).
The first hypothesis is that the kidneys may be directly attacked by SARS-CoV-2. We know some of the protein spikes that surround the virus act as “keys” that fit into certain cell-surface receptors. Just like in our macro world in which the right key can allow entry through an exterior barrier, if a virus has the right key, it is allowed entry into a cell. The key that SARS-CoV-2 has fits into a receptor on our cells called the angiotensin-converting enzyme 2 (ACE2) receptor. Kidney cells are abundant in this type of receptor (as are the lungs and heart), thereby making the kidneys especially susceptible to attack by this coronavirus.
Second, kidney injury could be the result of an initial lung injury. Lung damage is one of the hallmarks of infection with COVID-19. When the lungs are damaged, they cannot extract enough oxygen from the air to supply the rest of the organs with that vital oxygen supply. Because of the this, the kidneys could be damaged.
A third possibility is that infection with SARS-CoV-2 could cause a person’s immune system to overreact and subsequently attack some of its own internal organs. The kidney is one of the organs that is vulnerable to such an autoimmune attack, often referred to as a hyperinflammatory reaction or a cytokine storm.
Lastly, we’ve seen that infection with the novel coronavirus affects the circulatory system and increases the ability of the blood to form clots within the blood vessels. These clots could travel to the vessels in the kidneys and thereby cut off the oxygen supply leading to kidney injury.
To sum up, here are the leading hypotheses for mechanism of kidney injury in COVID-19 patients:
- Direct attack by SARS-CoV-2 on ACE2 receptors in the kidneys
- Reduced oxygen supply to kidneys secondary to lung damage
- Immune system overreaction and subsequent autoimmune attack on kidneys
- Increased clotting in the blood cutting off oxygen supply in kidneys
What Does This Mean in Pregnancy?
When you’re pregnant, the volume of blood circulating throughout your body increases. This means the kidneys are working extra hard to support you during this time by increasing the rate at which they are filtering all that blood by up to 50%. Anything that could disrupt the function of your kidneys during pregnancy could potentially be harmful to both mother and baby. Kidney injury during pregnancy could lead to hypertension (high blood pressure), preeclampsia, preterm birth, intrauterine growth restriction (a condition in which the fetus does not grow as quickly as it should), or miscarriage.
At this point, there is still no vaccine to protect us from contracting COVID-19. It’s best to do everything you can to avoid getting it, especially during pregnancy. Things you can do to help stay healthy during this pandemic are: frequently wash your hands with soap and water, practice social distancing by staying at least 6 feet away from others, make sure others know how important it is to wear a mask, and stay home as much as possible.