The waste products in the blood are filtered into the urine and can occasionally form crystals that collect inside water space in the kidneys. Over time, the crystals may build up to form a hard stone-like lump. This is more likely to happen if you don’t drink enough fluids, if you’re taking some types of medication, or if you have a medical condition that raises the levels of certain substances in your urine.
After a kidney stone has formed, your body will try to pass it out when you go to the toilet (in the urine). This means it will often travel through the urinary system (the kidneys, kidney tubes (ureters), bladder & urethra). Kidney stones can develop in one or both kidneys and can affect people of any age, most commonly between 30 and 80 years of age.
They are quite common, with around three in 20 men and up to two in 20 women developing them at some stage of their lives. The medical term for kidney stones is nephrolithiasis, and if they cause severe pain it’s known as renal colic.
Small kidney stones may go undetected and be passed out painlessly in the urine, but a stone can block part of the urinary system, such as the:
A blockage can cause severe pain in the abdomen or groin and sometimes causes a urinary tract infection (UTI).
Aim for a fluid intake of 3 liters because it reduces the chance of stone formation. Have a mix of water, fruit juices (in moderation), soup, coconut water, decaffeinated teas, and mineral water.
Avoid fizzy drinks as they have lots of sugar, drinks with artificial sweeteners (as they make it difficult to rehydrate), and high quantities of caffeinated drinks.
Keeping your urine diluted helps to stop waste products becoming too concentrated and forming stones.
You can tell how dilated your urine is by looking at its color. The darker your urine is, the more concentrated it is.
Your urine is usually a dark yellow color in the morning because it contains a build-up of waste products that your body has produced overnight.
You should also make sure you drink more when it’s hot or when you’re exercising, to replenish fluids lost through sweating.
Moderating salt intake is very important. Avoid adding salt to food, and avoid salty meals (ready-made meals often contain a lot of salt) use herbs and spices for flavor instead. You can check the amount of salt on the food label.
The western diet increases the prevalence of kidney stones with high consumption of dairy, legumes, meat and grain, which can make urine high in acid.
Other dietary modifications can help, dependent on the type of stone you produce. Please see individual sheets for types of stone. A dietician may be able to provide more information.
Medication may be prescribed to alter the acid level (pH) of urine to try to prevent stone formation. Other medication may include diuretic therapy that reduces the calcium levels in your urine (Please see individual stone information).
You may also be given a prescription for painkillers, anti-sickness medicine, or both, for management of symptoms of kidney stones. The Doctor may prescribe alpha-blockers to help stones pass.
Larger stones may need to be broken up using ultrasound or laser energy. Occasionally, keyhole surgery may be needed to remove very large kidney stones directly.
It’s estimated that up to half of all people who have had kidney stones will experience them again within the following five years.
Blocked ureter and kidney infection
A kidney stone that blocks the ureter can lead to a kidney infection.
This is because waste products are unable to pass the blockage, which may cause a build-up of bacteria.
It is important to establish what type of kidney stone you have so appropriate treatment and dietary advice can be given. We can do this by analysis of any stones you have collected or sometimes from special laboratory urine tests.
Kidney stones come in a variety of sizes, shapes and colors. Some are like grains of sand, while in rare cases others can grow to the size of a golf ball.
The main types of kidney stones are:
Calcium Containing Stones:
Recurrent Kidney Stones:
Some people are particularly likely to keep on developing kidney stones, including people who:
If you’re referred to hospital for an imaging test, a number of different techniques may be used. Imaging tests can help confirm the diagnosis, or identify precisely where a kidney stone is.
These tests include:
Most kidney stones are small enough (less than 4mm in diameter) to be passed out in your urine and can probably be treated at home.
Treating Large Kidney Stones
If a kidney stone is too big to be passed naturally – 6-7mm (about 0.23 to 0.27in) in diameter or larger – you may need treatment to remove it another way.
This could include:
These procedures can be explained in more detail in other literature or during your consultation if required. The type of treatment you have will depend on the size and location of your stones.
You should seek urgent medical attention if:
The best way of preventing kidney stones is to make sure you drink plenty of water each day to avoid becoming dehydrated.
Making pH of urine more Alkaline:
Calcium phosphate stones mostly occur during pregnancy.
To try to prevent stone formation, urine needs to be more acidic: aim for urine pH of 6.5
Adding food and drink that can increase urine acidity can help:
Most nuts, beans, meat, fish and grains can cause urine to be more acidic so this can be helpful.