Kidneys
Kidneys
Understanding kidney disease courtesy of
Kidney Health
Australia
External Link
Your kidneys are as important to your health as your
heart
or
lungs
. Their main job is to remove waste products from your body. Most people have two kidneys, one on either side of the spine under the lower ribs. They are bean-shaped and reddish brown in colour. Each kidney is about the size of a clenched fist.
Kidneys are a filter system
The main job of the kidneys is to remove waste from the
blood
and return the cleaned blood back to the body. Each minute about one litre of blood – one-fifth of all the blood pumped by the heart – enters the kidneys through the renal arteries. After the blood is cleaned, it flows back into the body through the renal veins.
Each kidney contains about one million tiny units called nephrons. Each nephron is made up of a very small filter, called a glomerulus, which is attached to a tubule. As blood passes through the nephron, fluid and waste products are filtered out. Much of the fluid is then returned to the blood, while the waste products are concentrated in any extra fluid as urine (wee).
The urine flows through a tube called the ureter into the
bladder
. Urine passes from the bladder out of the body through a tube called the urethra. The kidney usually makes one to two litres of urine every day depending on your build, how much you drink, the temperature and the amount of
exercise
you do.
A healthy kidney can greatly increase its work capacity. With two healthy kidneys, each kidney performs 50 per cent of the normal kidney function. If one kidney is lost, the other kidney can enlarge and provide up to 75 per cent of the normal kidney function (the work of one and a half normally functioning kidneys).
Other kidney functions
As well as filtering the blood, kidneys:
make and regulate important hormones in the body that help to control
blood pressure
, red blood cell production and calcium uptake from the intestine
maintain body fluid at the correct levels for the body to function
control body chemistry by regulating the amount of
salt
,
water
and other chemicals moving around the body.
Measuring how your kidneys work
It is difficult to calculate the exact rate at which your kidneys work. The best measure of kidney function is called the glomerular filtration rate (GFR). The GFR can be estimated (eGFR) using a mathematical formula. This formula uses the level of creatinine in your blood to estimate how well your kidneys are filtering waste from your blood. It can indicate if there is any kidney damage.
The higher the filtration rate, the better the kidneys are working. A GFR of 100 mL/min/1.73 m2 is in the normal range. This is about equal to ‘100 per cent kidney function’. Based on this measurement system, a GFR of 50 mL/min/1.73 m2 could be called ’50 per cent kidney function’ and a GFR of 30 mL/min/1.73 m2 could be called ’30 per cent kidney function’.
If your doctor orders a blood test to learn more about your kidney function, an eGFR result is provided automatically, along with your creatinine results.
Your doctor may also test for other signs and conditions that may indicate you have chronic kidney disease. These may include tests for:
protein
in your urine (albuminuria or proteinuria)
blood in your urine (haematuria)
high blood pressure
diabetes
.
Keeping your kidneys healthy
Well-functioning kidneys are essential to your overall health. Early detection of kidney disease can be life-saving. Medication and changes to lifestyle, along with an early referral to a kidney specialist, can prevent or delay kidney failure.
If you are at increased risk of
chronic kidney
disease
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, talk to your doctor about having a regular kidney health check.
Where to get help
Your
GP (doctor)
Kidney Health
Australia
External Link
Helpline Tel.
1800 454 363
Kidney Health Australia -
Know your kidneys
factsheet
External Link
Kidney Health Australia -
Keeping your kidneys healthy
factsheet
External Link