The science of COVID-19

COVID-19 and the human kidneys: An Overview

Dr. Chris Prashad

Article submitted as part of the Ministry of Health’s COVID-19 public information and education programme. For questions, email [email protected]
We can all appreciate that COVID-19 is a deadly condition that primarily affects the respiratory system. The effects of COVID-19, however, can directly or indirectly affect many other organs, with kidney injury being recognized more prominently as data becomes available.
Normally, humans have two kidneys that are best known for their role of filtering our blood and allowing us to get rid of toxic substances by excreting them in urine. Along with this critical function, the kidneys also have a role in regulating blood pressure and maintaining certain hormones in our body.
Without properly functioning kidneys, we would not be able to live — at least not without the help of an artificial way of removing toxins such as dialysis.

Effect on Kidneys
There are many gaps in our understanding of COVID-19, but we have several scientific clues as to how this disease affects the kidneys.
1. COVID-19 can directly infect the kidneys: this virus is thought to use a substance called the angiotensin converting enzyme 2 (ACE2) to enter and infect the cells of the body. ACE2 receptors can be found abundantly in the kidneys, making this organ a prime target for the novel coronavirus, which in turn can directly cause kidney injury.
2. COVID-19 can cause a cytokine storm: when infected, the body reacts by producing an immune response which increases the production of certain inflammatory factors and other substances to fight the illness. In some persons, the reaction to infection can be extreme, leading to an overwhelming production of inflammatory substances, a situation referred to as a cytokine storm. The cytokine storm in an effort to kill the invading virus can also destroy healthy tissue, including that of the kidneys.
3. Other underlying factors: persons that become severely ill from COVID-19 may have pneumonia, low blood pressures (sepsis) and clotting disorders, affecting the oxygen supply to the kidneys and inevitably leading to injury. Those with underlying diseases like diabetes, cardiovascular conditions, or cancer are also more susceptible to kidney injury from COVID-19.
As with the lungs and the respiratory system, COVID-19 can affect the kidneys along a spectrum, starting with mild to moderate damage that usually gets better as the person recovers, to more severe instances, which can impair the kidney functions more permanently.
COVID-19 can injure and impair the kidneys to the extent where the person may require lifesaving dialysis — the majority of these patients being already critically ill from the respiratory effects of coronavirus.
Currently, there is evidence that leads us to believe that severe infection with COVID-19 can lead to chronic kidney disease for those that had normally functioning kidneys, while worsening the condition of the kidneys for those already suffering from chronic kidney disease. Acute kidney injury in COVID-19 is also associated with a higher risk of death.

Diagnosis
Kidney functions are usually assessed by simple and widely available blood tests (commonly referred to as BUN and Creatinine), or more complex measures when necessary (glomerular filtration rate, renal biopsy).
The physician will look for certain trends in your renal function blood tests, combined with an observation of urine output to determine whether a person has suffered kidney injury. The management of patients with a confirmed diagnosis of COVID-19 and acute kidney injury is individualized, but will generally include:
1. Targeting the underlying COVID-19 with the use of antibiotics, antivirals, immunomodulatory and anti-inflammatory drugs.
2. Maintaining a good blood pressures and fluid balance with the use of intravenous fluids and pressure support drugs as necessary.
3. In cases of critically ill patients, about one-third may require some form of dialysis.

High Risk
Persons already living with underlying kidney disease are at a very high risk and in an extremely vulnerable group for becoming severely ill with COVID-19. This is especially so if someone is on dialysis, had a kidney transplant, has high stage chronic kidney disease, or is using prednisolone daily (being treated for an autoimmune condition).
It is worth noting that persons with chronic kidney disease are at a three-fold higher risk of developing severe and life-threatening symptoms from COVID-19 when compared to persons without chronic kidney disease.
If you are someone that already has underlying kidney disease, it is recommended that you adhere to protective guidelines. If you are on dialysis, you should not miss your treatments, but if you feel sick, ensure you inform a member of your healthcare team.
COVID-19, as well as the circumstances around it, has influenced all of our lives in Guyana, requiring us to adapt in so many different ways. This article allows us to understand a little more about the far-reaching consequences of this deadly disease.
Properly functioning kidneys are essential for life, and therefore it is in everyone’s best interest that they pay attention to the health of these organs. As COVID-19 continues to be at the forefront of our conversations, we should be aware that in Guyana there are many more common conditions that adversely affect and otherwise injure our kidneys.
Diseases such as diabetes, high blood pressure and renal stones continue to be responsible for acute and chronic kidney injury for many Guyanese and this should not be less of a priority.
If you are diagnosed and living with a chronic illness like diabetes and high blood pressure, it is important that you have regular follow up assessments with your medical practitioner, as control of these conditions is often paramount in preserving the health of your kidneys.
Self-medicating is strongly discouraged! For those with no known illnesses, it is still important that you have a conversation with your doctor about the status of your kidneys and be guided accordingly.

Things to Remember
1. Kidney injury is common in severe cases of COVID-19 and is associated with a poor outcome.
2. COVID-19 can damage the kidney by several different mechanisms.
3. Treatment options revolve around treating the underlying COVID-19 as well supporting the kidneys with medication, fluids and dialysis if required.
4. Kidney injury from COVID-19 can be long term.
5. If you already have underlying kidney disease you are more likely to suffer severe illness from COVID-19 – you need to be proportionately more cautious in your actions.
6. In Guyana, many other common conditions affect our kidneys adversely and warrant our attention.

Article submitted as part of the Ministry of Health’s COVID-19 public information and education programme. For questions, email [email protected]