fbpx Skip to main content

5 Facts About The Kidneys

By 09/03/2021November 10th, 2021No Comments

With World Kidney Day taking place on Thursday 11th March, we look at the kidneys and find some interesting facts about them for you to enjoy.

1. The kidneys are bean shaped

The kidneys are essential organs for human health. They have many vital roles in the body particularly removing toxins and excess water from the blood. Most people are born with two kidneys, both are bean shaped and are approximately 10-12 cm long. They are about the size of a clenched fist.

The kidneys are situated just under the ribs and above the waist at the back, one on the left and one on the right.

2. They filter 180 litres of blood per day

The kidneys are responsible for filtering the blood. They remove waste and toxic substances from the body and put useful things like vitamins, glucose, amino acids, and hormones back in.

That’s not all the kidneys do, they also:
• balance the body’s fluids
• remove drugs from the body
• release blood pressure regulating hormones
• regulate the production of red blood cells
• produce an active form of vitamin D which promotes strong, healthy teeth and bones

3. Losing one kidney only reduces kidney function by 25%

Many people are born with one kidney whereas some people need to have one surgically removed due to a tumour or a severe traumatic injury. The human body can survive with just one kidney and some research has shown that people who have had a kidney removed can increase the function of the remaining kidney.

The increased function can be as high as 70% of the usual function achieved by having two kidneys. People born with one kidney, however, usually have a normal overall kidney function.

Living with one kidney requires a little more protection than someone who has two. Often people with one kidney are advised to avoid sports such as:
• Hockey
• Boxing
• Football
• Martial arts
• Wrestling

4. Nephrons are the filtering units of the kidneys

Each of your kidneys contain small filtering units called nephrons. Each kidney is made up of 1-2 million nephrons which each contain a glomerulus, the filtering part, and a tubule.

They work in two stages. The glomerulus filters the blood while the tubule returns the useful substances the body needs back to the blood.

If the nephrons were removed from both kidneys and laid out end to end, they would cover 10 miles.

5. The kidneys produce vitamin D

Vitamin D is known as the sunshine vitamin because humans get most of their intake from the sun. When the skin is exposed to the suns UVB rays, it makes vitamin D, which is needed to promote calcium absorption in the gut, promoting strong, healthy bones.

The kidneys have an important role in vitamin D synthesis because they convert it into the active form needed by the body. People who have chronic kidney disease often have low vitamin D levels because the damaged kidneys are less effective at converting vitamin D to its active state.


The kidneys are a vital organ for human health, carrying out a variety of important functions including filtering the blood. Despite many people being born with two kidneys, some people are born with just one while others may have to have one removed at some point during their lifetime. However, the body can cope with one kidney and, if it is surgically removed, can even increase its function. Clever stuff, right?
Remember you can help look after your kidneys by drinking plenty of water and staying hydrated. If you have purchased one our Hydratem8 tracker bottles you’ll have received one of our pee charts, so you’ll be able to visually see if you are hydrated just by looking at the colour of your pee.


Kidney Research UK. (2021). Living with One Functioning Kidney. Available at: https://kidneyresearchuk.org/kidney-health-information/questions-about-kidney-disease/living-with-one-kidney/
National Health Service. (2021). Keeping Your Kidneys Healthy. Available at: https://www.nhs.uk/live-well/healthy-body/keeping-your-kidneys-healthy/
National Institutes of Health. (2020). Vitamin D. Available at: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/

Leave a Reply