All about our kidneys - we can't live without them!
We can live quite well with only one kidney and indeed, some people live healthily even though born with one missing. But while bones can break, muscles can waste away and the brain can sleep without risk to life, if both kidneys fail, as happens in end stage kidney failure, bone, muscle or brain can not carry on. Without any kidney function our body dies. Kidney function is essential for life!
 Where are your kidneys? The human kidneys are small, biological marvels with a fascinating design that fulfill a vital function. Most people are born with two kidneys; each bean shaped organ is about the size of a fist located just below the rib cage on either side of the spine. Each kidney is about 11.5 cm long, 5 to 7.5 cm broad and 2.5 cm thick, weighing about 150 grams and are located near the middle of your back, just under the ribcage.
Healthy kidneys act like a filter to make sure the right amount of wastes and fluids are removed, they keep the proper balance of salts and acids in the body and produce hormones. Every day our kidneys perform an essential job of filtering 200 litres of blood, to remove about 2 litres of waste products and unneeded water.
What do your kidneys do? Your kidneys intervene in numerous processes and balances of the body and control many vital body functions and are amazing master chemists of the body. The major role of the kidneys is to remove waste from the blood and eliminate it in the urine. To remove this waste and extra water, blood enters the kidney through the renal artery; blood is then cleaned in the kidney as it passes through tiny filters called nephrons. One kidney contains about one million nephrons. Each nephron contains a filtering apparatus called a glomerulus.
We have about a million hairpin-like glomeruli at birth, but lose about 100,000 of these every decade of life. Droplets of filtered blood pass through a number of tubules (tiny tubes) into the medulla, a central collecting region. The glomeruli and tubules together make up nephrons, long and extremely fine tubes which, if connected, would run for 80 kilometres (50 miles). The nephrons are the basic working units of the kidneys, controlling the formation of urine.
Cleaned blood returns to the body by the renal vein. Waste and extra water removed by the kidney passes through a tube called the ureter to the bladder where it is stored as urine or wee. When the bladder is full, the urine passes out of the body through another tube called the urethra. ( See interactive diagram below for graphic example).
The process of removing waste and extra water in simple terms is:
- Food and drink enters the stomach and are broken down into nutrients.
- Solid waste products are removed and nutrients enter the bloodstream.
- Nutrients are used by the body for energy, growth, repair and maintenance of body functions.
- This process creates waste which is removed by the kidneys.
- Extra nutrients not immediately needed by the body are also removed by the kidneys.
- Waste products and extra water move from the kidneys to the bladder then leave the body as urine (wee).
Our kidneys also make three important hormones, erythropoietin, renin and Active vitamin D. Erythropoietin stimulates the production of red blood cells, renin is involved in the control of blood pressure and Active vitamin D controls calcium uptake and helps make strong bones.
The kidneys are designed to last a life-time. They do an amazing job! It is important to be kind to them.
We recommend the kidney education tools below as an excellent introduction to the world of the kidney. Click on the links above kidney diagrams to view animated presentations which show where the kidneys are in your body, what they do and how they do it. Also see how dialysis works. Then do the quiz below to test your knowledge at the bottom of this page.
 
Structure of the kidneys and bladder Diagram of how a healthy kidney works
Note: Some statements in the quiz and the animations above refer to USA measurements.To convert to Australian legal units of measurement, refer to Australian Government website www.measurement.gov.au/index.cfm?event=conversions
Kidney Health Australia acknowledges the generosity of DaVita (USA) for kindly allowing us to host this excellent teaching resource on our website. DaVita is an American company who provide dialysis services to those diagnosed with CKD.
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What can go wrong with the kidneys? People can live a near normal life with as little as 20 percent of their total kidney function. There are often no symptoms in the early stages of many kidney conditions. When they do occur the initial signs may be general, such as feeling tired or generalised itching. As kidney disease progresses, the symptoms can include changes in the urine (reduced volume, discolouration, blood or pus), nausea and vomiting and appetite loss. Other symptoms include swollen or numb hands and feet (because of water retention), weakness and lethargy, darkened skin and muscle cramps.
When the kidneys become damaged, do other organs suffer as well? Most kidney diseases attack the nephrons, slowly destroying their filtering capacity over many years, seriously damaging your kidneys before you even know it. Some kidney diseases, such as polycystic kidney disease are inherited, but the two most common causes of kidney disease are diabetes (diabetic nephropathy) and high blood pressure (hypertension). In diabetes high blood sugar levels damage the nephrons. High blood pressure can prevent the small blood vessels in the kidneys from filtering and cleansing the blood well enough. See Your heart and CKD.
What does the term Chronic Kidney Disease (CKD) mean? This term means that the kidneys have been damaged and are not working as well as they should normally.
How common is CKD? Around 1 in 10 people have CKD, however it is less common in young adults. In the older person it is more common due to the natural ageing of the kidneys. A number of diseases can damage the kidneys such as diabetes, hypertension (high blood pressure) and some inherited conditions. Almost all of these will damage both kidneys at the same time.
How do you know if you have CKD? In most cases CKD does not cause any symptoms and is detected because a test has shown an abnormality. It may be a urine test for blood or protein; an X-ray or scan of the kidneys; or a blood test to measure kidney function. Most cases are discovered by your GP/amily doctor as part of normal care.
Kidney disease progression can be slowed with medicines which protect your kidneys. Your GP can prescribe these medicines which are available through your local pharmacist.
What can I do to help stay healthy? Key recommendations to staying healthy are to keep your blood pressure below 130/90 and maintain healthy levels of cholesterol. It’s important to have your cholesterol levels checked regularly. The recommended level is no higher than 5.5 mmol/litres. Lead a healthy lifestyle and maintain healthy weight, be active for more than 30 minutes most days, eat a balanced healthy diet, become a non smoker. If you have diabetes make sure you actively treat your blood glucose. Normal blood glucose levels are 4-6 mmol/L before meals and 4-8 mmol/L two-hours after meals. See MeasureUp and CKD.
A urinary tract infection (UTI) should be treated promptly as a kidney infection is serious. It is important to see a doctor if a kidney infection or kidney stones are suspected because lasting damage or even kidney failure can occur if these conditions are left untreated. Infection which has spread from cystitis or pyelonephritis can be life threatening.
The food you eat plays a huge role in the health and well being of your body. It can help to prevent some diseases, and to manage others. As well as providing the body with a variety of nutrients, food choices can also help in weight reduction and weight control. Individuals who are overweight are at an increased risk of developing diabetes and high blood pressure, major risk factors for kidney disease. In fact, losing as little as five kilograms reduces blood pressure in most people who are 10 per cent over their healthy weight.
Drinking water instead to satisfy thirst is recommended rather than sugar-containing soft drinks and is one way to lose weight. Water is the recommended fluid to satisfy thirst and is nature's choice. It is calorie-free, inexpensive and readily available and choosing to drink water instead will also have a positive impact on your health. It can also contain fluoride which is good for the teeth.
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Kidney Quiz
1. How many kidneys do human bodies usually have?
a. One
b. Two
c. Four
2. Where are your kidneys located?
a. Near the middle of your back
b. On the right side of your chest
c. Below your belly button
3. How big are kidneys?
a. The size of a pea
b. The size of a soccer ball
c. The size of an adult fist
4. What do kidneys do?
a. Remove waste and fluid your body does not need
b. Help to control blood pressure
c. Help with making red blood cells
d. Help to keep bones strong
e. All of the above
5. What are the risk factors for kidney disease?
a. Diabetes
b. High blood pressure
c. Being overweight.
d. Smoking
e. All of the above
6. If you get end-stage kidney disease, what will a doctor need to do to help you?
a. Dialysis and organ transplantation
b. Just medication
c. Surgery to repair your kidneys
d. All of the above
7. How many Australian adults are at risk of kidney disease?
a. 1 in 3
b. 1 in 13
c. 1 in 33
d. 1 in 130
Updated 3 February 2010 Answers 1.b 2.a 3.c 4.e 5.e 6.a 7a
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