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COVID-19 and the Kidneys

July 08, 2020 5 min read

COVID-19 and the Kidneys

Dr. Sandra El Hajj -MSc, N-MD, DHSc

COVID-19 is a viral infection that has affected the entire globe these past few months. This infection affects everyone and its symptoms range from mild to severe. While young healthy individuals do not seem to be severely impacted by COVID-19, older adults and individuals with existing chronic conditions have been severely affected.

Symptoms start surfacing up 2 to 14 days post-exposure and include a cough, shortness of breath, fever and chills, muscle pains, sore throat and loss of taste and smell. Some other reported symptoms include nausea, vomiting and diarrhea. COVID-19 affects many organs of the body including the kidneys.

Why are kidneys important?

There are two kidneys, located on either side of the spine at the lowest level of the rib cage. Each kidney contains up to a million functioning units called nephrons, which is where blood filtration takes place. A nephron consists of a unit of tiny blood vessels called a glomerulus attached to a tubule. The glomerulus is responsible for the blood filtration while the tubules are responsible for either the reabsorption or secretion of water as well as other essential compounds such as glucose, electrolytes and proteins. Excess fluid containing wastes are then excreted out of the body through the urine.

Kidneys play a very important role in the removal of waste products and excess fluid from the body through the urine. This function of the kidneys is very important for maintaining a balanced supply of essential compounds to the body while removing waste products that may cause harm. The critical regulation of the body's salt, potassium and acid content is also performed by the kidneys.

Kidneys also produce hormones that affect the function of other organs. Specifically, their function is to remove waste products and drugs from the body, help balance the body's fluids, release hormones that regulate blood pressure, produce an active form of vitamin D that promotes strong, healthy bones and control the production of red blood cells.

Possible causes of kidney diseases

Chronic kidney disease is defined as having abnormalities in the proper functioning of one or the two kidneys. As a result, kidney function will get disrupted allowing such as the presence of protein in the urine and having decreased kidney function for a period of three months or longer. There are many causes of chronic kidney disease. Some kidney conditions are inherited, while others are congenital or in-born. The following are general causes of kidney damage:

  • Diabetesis the leading cause of kidney disease. Diabetes is a metabolic condition primarily due to decreased production or improper utilization of insulin, which is needed to facilitate glucose entry to cells for metabolism. However, if there is no insulin or insulin is not utilized at all, glucose cannot enter the cells and therefore leads to increased glucose levels in the blood. This results in a high blood sugar level, which can cause problems in many parts of your body including the kidneys.
  • High blood pressureis also known as hypertension, which occurs when the force of blood against the artery walls increases. Over time, uncontrolled high blood pressure can cause arteries around the kidneys to narrow, weaken or harden which causes irreparable damage to the kidneys. The damaged arteries will no longer be able to deliver enough blood.
  • Urinary tract infections occur when germs and bacteria enter the urinary tract and cause infection. This is manifested as symptoms such as pain and/or burning during urination and a more frequent need to urinate. These infections often affect the bladder, but they sometimes also spread to the kidneys.
  • Congenital diseases may also affect the kidneys. These conditions affect a baby while developing in the mother's womb. One of the most common causes occurs when a valve-like mechanism between the bladder and ureter (urine tube) fails to work properly and allows urine to back up (reflux) to the kidneys, causing infections and possible kidney damage.
  • Drugs and toxins can also cause kidney problems. Using large numbers of over-the-counter pain relievers for a long time may be harmful to the kidneys.
  • Glomerulonephritis is a disease that causes inflammation of glomerulus due to prolonged infection. Glomerulonephritis may suddenly occur or may develop over time.
  • Polycystic kidney disease is the most common inherited kidney disease. It is characterized by the formation of kidney cysts that enlarge over time and may cause serious kidney damage and even kidney failure.
  • Kidney stones are very common, and they may cause severe pain in the back and side. There are many possible causes of kidney stones, including an inherited disorder that causes too much calcium to be absorbed from foods and urinary tract infections or obstructions.

Alarming kidney disease symptoms

Kidney disease usually affects both kidneys. If the kidneys' ability to filter the blood is seriously damaged by disease, wastes and excess fluid may build up in the body. Although many forms of kidney disease do not produce symptoms until late in the course of the disease, there are six warning signs of kidney disease:

  1. High blood pressure, blood and/or protein in the urine
  2. A creatinine and blood urea nitrogen (BUN) blood test outside the normal range
  3. A glomerular filtration rate (GFR) less than 60 ml/min
  4. Puffiness around eyes
  5. Swelling of hands and feet
  6. More frequent urination particularly at night accompanied by difficult or painful urination.

COVID-19 and kidneys

What existing cases show so far is that older individuals who have existing kidney disease and chronic conditions are more likely to exhibit serious COVID-19 related complications(1). These individuals should make sure they are well-protected and taking all precautions to avoid contracting the virus. Make sure you are not going to crowded public places, wearing masks and gloves as required, washing hands and sanitizing everything you buy from stores before using them.

Those who contract COVID-19 are at an increased rate for developing acute kidney failure(2). It is a severe complication that comes with as high as a 50% mortality rate. Despite this finding, more research is needed to link this novel virus to the kidneys.

When COVID-19 enters the body, it binds to receptors called ACE2. These enzymes are found in kidneys. These receptors and proteins/enzymes allow the viral cells to infiltrate our own body cells, allowing them to channel in. A second theory explains that kidney damage is a kind of secondary side effect caused by the lack of proper oxygen throughout the body. When COVID-19 attacks the lungs, it causes alveoli to collapse, resulting in disrupted oxygen flow to the entire body system including the kidneys.

Individuals who are using dialysis to filter blood outside of the body are facing a crisis due to COVID-19. This virus increases the formation of blood clots. So, the blood is not able to smoothly flow throughout the body. And, the presence of these clots is creating clogged filters in dialysis machines. This has led doctors to start using blood thinners in the treatment regimen.

In summary

Kidneys play a very important role in the removal of waste products and excess fluid from the body through the urine, and when compromised through illness or other complications, the impact can be serious, even leading to death.

COVID-19 has impacted many organs of the human body. Research is still young and we have a ways to go to fully understand the correct mechanism of this novel virus. But, with the proper dedication and study teams, more advancement can be made that can has a positive impact on mortality rates.