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 fulfil 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.
What do your kidneys do? 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.
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. Our kidneys 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.
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 animation below.
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).
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
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 What can go wrong with the kidneys?
Kidney disease is called a ‘silent disease’ as there are often no warnings.
- It is not uncommon for people to lose up to 90% of their kidney function before getting any symptoms.
- People can live a near normal life with as little as 20 percent of their total kidney function.
- When symptoms 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.
Are you at increased risk of developing kidney disease? Take our test to find out.
What does the term Chronic Kidney Disease (CKD) mean?
Chronic Kidney Disease This term means that the kidneys have been damaged and are not working as well as they should normally. About 50 people a day die of kidney related disease. Early detection and treatment can help prevent kidney failure and the need for dialysis or transplant treatment.
How common is CKD? 1 in 7 Australians over age 25 years have at least one clinical sign of existing CKD, such as reduced kidney function or evidence of kidney damage. 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 / family doctor as part of normal care.
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. Refer to our webpage Your heart and CKD and Diabetes and CKD.
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. Ring Medicine Line 1300 888 763 for independent pharmacist advice on prescriptions, over-the-counter, and complementary (herbal / natural / vitamin / mineral) medicines.
Urinary tract infections (also known as UTIs) 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.
Why do kidneys fail?
Inside each kidney there are about one million tiny units called nephrons which filter the blood. As blood passes through the nephron, water and waste products are removed. Most of the water returns to the blood and the waste products collect in the bladder then leave the body as urine (wee). Most kidney diseases attack the nephrons.
Sometimes kidney failure can happen quickly, caused for example by a sudden loss of large amounts of blood or an accident. A sudden drop in kidney function is called Acute Kidney Failure and is often short lived but can occasionally lead to lasting kidney damage.
More often kidney function worsens over a number of years. This is good news because if kidney disease is found early, medication, dietary and lifestyle changes can increase the life of your kidneys and keep you feeling your best for as long as possible. If you lose over 1/3 of your kidney function for over 3 months, it is called Chronic Kidney Disease (CKD). Sometimes kidney disease leads to kidney failure, which requires dialysis or a kidney transplant to keep you alive.
These are the different stages of chronic kidney disease used by doctors to determine the severity of the reduction of kidney function:
Early stages - small amount of kidney damage, although GFR may be normal
- Often there are no symptoms in the early stages of kidney disease, blood tests can be normal.
- There may be scarring and blockages that change blood flow to parts of the kidney so they don't work as well as they should.
- There is an increased risk of heart disease. You doctor can help you reduce your risk of heart disease.
Middle stages - sometimes discovered because the level of waste product in the blood rises
- Some people begin to feel unwell and notice an increase in urine frequency.
- Blood pressure can rise as the kidneys slow down. High blood pressure further increases the risk of heart disease, heart attack and stroke.
- Early signs of bone disease may be present.
- Anaemia may appear, caused when there are not enough red blood cells in the blood to carry oxygen around the body. Symptoms include weakness, fatigue and a shortness of breath.
Later stages
- High blood pressure almost always occurs.
- You may start to notice changes in the amount of urine you pass.
- Lack of energy, increased tiredness and reduced appetite are common symptoms.
- You may need to make dietary changes, including limiting the use of salt or reducing the amount of potassium or phosphorus in your diet.
End-Stage Kidney Disease
- The kidneys are only functioning at 10-15 per cent of their capacity and are unable to properly filter waste products, remove extra water from the body and help maintain the blood's chemical balance.
- This is the time to consider commencing dialysis or having a kidney transplant.
What can I do to help stay healthy?
Key recommendations to staying healthy are:
- 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.
 Healthy Eating 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.
- Eat healthy food
- Don't over eat - always leave a meal feeling like you could eat a little bit more
- Eat breakfast - a good breakfast activates your metabolism first thing in the morning
- Avoid fad diets - they are hard to maintain over a long period and can create or worsen ill health
- Drink plenty of fluids - choose water instead.
- Sugar drinks have lots of calories, while caffeine and alcohol are both diuretics and can leave the body dehydrated, and check nutrition panels and choose foods with a low percentage of sugar and salt and which are low in saturated fats
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. See Measure Up and CKD and associated pages for more detail.
Be or remain a non-smoker It is well known that smoking harms your health. Smoking causes narrowing of the arteries including small vessels that are in the filter in sections of your kidney. This reduces the ability of the kidneys to work properly. Smoking has been linked to cancer of the kidneys, the bladder and ureter (the small tubes that run from your kidneys to the bladder). The message is clear: don't smoke. If you do smoke, giving up is one of the best things you can d to keep your kidneys healthy.
Maintain healthy weight Being overweight or obese can lead to other health problems such as lifestyle diseases like diabetes and high blood pressure - which are also factors that could lead to chronic kidney disease.
 Losing weight can reduce how hard your kidneys have to work. Weight loss can also lead to a decrease in the amount of protein lost via urine. High levels of protein in the urine can make your kidney function worse. Obesity may also cause some people with existing forms of some kidney disease to loose their kidney function more rapidly. There is also some evidence that suggests that excess weight is associated with an increased risk of kidney cancer.
Stay fit Do at least 30 minutes of physical activity most days of the week. The key is to start slowly, and gradually increase time and intensity of activities. Physical activity leads to increased strength, stamina and energy. You can also break down the activity into 3 x 10 minute bursts which can be increased as fitness improves.
However, if you experience any of the following symptoms, it is important to stop exercising and tell your health care team or go to the hospital: 
- chest pain or pressure
- feel dizzy or light headed
- irregular or fast heart beat that persists when the activity is completed
- or excessive shortness of breath
Don't drink too much alcohol It's important to be smart about your alcohol intake. While there are some studies that show alcohol causes no harm to the kidneys, it may be dangerous if you already have kidney problems. Alcohol makes your kidney produce more urine than normal, and excessive drinking can have a negative impact on other parts of the body that may contribute to kidney damage, such as the liver. There have been studies that have shown that heavy drinking may contribute to high blood pressure and heart disease, which over time may contribute to kidney disease. Alcohol has a high sugar content and therefore may lead to weight gain, another risk factor for kidney disease. See Australian guidelines to reduce health risks from drinking alcohol.
How many alcoholic drinks can you have without it affecting your kidneys? There is good evidence to suggest that one standard drink for women and the elderly (e.g.100ml wine; 285ml full strength beer; 30 ml spirit) or two standard drinks for men, three to four times a week may have a positive health effect. To avoid dehydration caused by more frequent urination, ensure you alternate between alcoholic and non-alcoholic drinks and remember to be smart about your drinking habits.
 Drink water instead To satisfy thirst, water is the recommended choice, rather than sugar-containing soft drinks. It is also calorie-free, inexpensive and readily available. Research in the USA states that one drink containing sugar each day has been shown in females to be associated with an 80 per cent increase in the risk of acquiring diabetes.
Note that bottled mineral water contains salt which can lead to fluid retention and swelling and even increased blood pressure in susceptible people. Check the label and choose low sodium varieties (less than 30mg sodium per 100ml).
Quick links Fact Sheets - Health Publications - Informative Weblinks - Organ Donation
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Take our Kidney Quiz Do you know how your kidneys work?
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. Are over 50 years
d. Being overweight
e. Family history of kidney disease
f. Smoking
g. Are of Aboriginal or Torres Strait Islander descent
h. All of the above
Top Answers 1.b 2.a 3.c 4.e 5.h
Updated 2 September 2010
Disclaimer: This is intended as a general introduction to this topic and is not meant to substitute for your doctor's or health professional's advice. All care is taken to ensure the information is relevant and applicable to each Australian state. It should be noted Kidney Health Australia recognises each person's experience is individual and variations do occur in treatment and management due to personal circumstances. Should you require further info always consult your doctor or health professional.
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