They can be excruciatingly painful – but what exactly are kidney stones? And what can you do about them?
Kidney stones have made it onto the list of top 20 most painful conditions according to the NHS, alongside broken bones, appendicitis and slipped discs. But what causes kidney stones – and how do you know if they are responsible for the pain you are experiencing?
We look at kidney stones symptoms, causes, treatment and prevention tips:
What are kidney stones?
Kidney stones are abnormal solid particles found within the urinary tract that should not normally be there. They are made from waste products in the blood that form crystals that can collect in the kidney.
Stones can then be found in any part of the urinary tract. This includes the kidneys, the collecting system of tubes that drains the kidneys and the ureter that drains down to the bladder or even in the bladder itself or urethra (tube from bladder to outside).
Stones can develop in one or both kidneys and can range from the size of a small grain of sand to (more rarely) a few centimetres in diameter like a small pebble. Larger stones are formed if the crystals build up over time into a lump. Stones can be yellow to brown to almost black and the shapes vary. They are not the same as gallstones.
💡 The medical name for stones is ‘calculi’. The medical term for stones that develop in the kidneys is ‘nephrolithiasis’ and the pain they can cause is ‘renal colic’.
Kidney stones symptoms
Kidney stones don’t always cause problems and some people never know they have them. Small kidney stones can easily go undetected and then be passed out painlessly in the urine. However, a stone can block part of the urinary system, such as the kidney or even try to travel down the ureter (tube from the kidney to bladder). This is a narrow tube and the stone can cause immense pain as it tries to pass through.
The pain felt from a stone will depend on where it is and can be potentially felt in the tummy, back or groin and can sometimes cause a urinary tract infection (UTI) or infection or blockage in the kidney.
Kidney stones symptoms include:
- A persistent ache or in the lower or upper back, side of the abdomen or groin. In men this may be felt in the testicles or scrotum.
- There may be bouts of intense or intermittent pain lasting for minutes or hours.
- Difficulty lying still, feeling restless.
- Needing to wee more often.
- Pain when weeing (dysuria).
- Smelly or cloudy urine.
- Blood in the urine (haematuria) from the stone ‘scratching’ the kidney or ureter.
- Feeling generally unwell.
- If a kidney infectionis also present, there may be a fever with a high temperature of 38 degrees celsius or above, the chills and weakness.
Kidney stones causes
What causes kidney stones? Having a kidney stone is not your fault but there may be things you can do to prevent it happening again. It is normally a result of the build up of certain chemicals in the body or not drinking enough, or a combination of factors. Understanding what causes kidney stones can help prevent it happening again or further stones forming.
- Kidney stones are more likely if you do not drink enough fluids– whatever the type of stone.
- Certain medical conditions or medications can make stones more likely to form. Medicines account for about one per cent of stones.
- Excesses of certain substances in your diet can encourage stone formation – especially if enough clear fluids are not consumed.
Kidney stones types
Kidney stones can be formed from crystals that contain various substances. For each one there may be different causes. There are four main types of stones:
- Calcium oxalate stones
Calcium oxalate stones are the most common type of kidney stone. Calcium oxalate stones are caused by too much of something called ‘oxalate’ in the urine. Oxalate is a natural substance found in many foods that can form crystals in the urine.
- Uric acid stones
This substance is made in the body when food is broken down for energy. These stones are more common in people with gout, those who eat a very meat-rich diet, people having chemotherapy or those with inherited conditions that elevate their uric acid levels.
- Struvite stones
Struvite stones are caused by bacterial infections, so they are common after recurrent chronic infections. These are the only kidney stones that are more common in women than men.
- Cystine stones
Cystine stones are caused by an inherited condition called cystinuria which affects the amount of acid in the urine. These stones are the only symptom of this condition.
Kidney stones risk factors
Men are generally more likely to have kidney stones than women. Studies show the number of people suffering is slowly increasing over recent decades, with about 12 per cent of people affected worldwide. This could be due to changes in lifestyle and diet.
Other kidney stones risk factors include:
- Extreme high-protein, low-fibre
- High sodium diets (increase sodium and calcium in urine).
- Being inactive or bed-bound.
- Obesity may encourage fluid loss from sweat and thus dehydration.
- Family history of kidney stones.
- Recurrent kidney or urinary infections.
- Only having one working kidney.
- Certain types of digestive system surgery or disease especially small bowel resections and crohn’s disease, as this decreases the body’s ability to absorb fat leading to increased chance of oxalate stones.
Can children get kidney stones?
Kidney stones are much more common in adults than in children. Any child who develops a kidney stone should always be thoroughly assessed to see if there is an underlying condition causing the problem, such as a metabolic disorder or a previously undiagnosed structural abnormality with the urinary system. Kidney stones can affect children of any age but typically tend to occur in teenagers most frequently.
Very rarely, some children may develop kidney stones after having a urine (water) infection but others are more at risk because of factors such as being born prematurely or having very limited mobility.
Most children only have one episode of kidney stones but if they are not completely cleared this can increase the risk of larger or further stones developing. Some children can have certain metabolic conditions that means they have a tendency to form kidney stones throughout their life and so need extra treatment to try to reduce these occurrences.
The diagnosis and treatment of kidney stones in children, as well as the advice given to help prevent them occurring, is the same as with adults.
Kidney stones diagnosis
Your GP will usually be able to diagnose kidney stones from your symptoms and medical history, particularly if you’ve had kidney stones before.
You will normally be asked to take a urine test and blood tests, to check that your kidneys are working properly, and to also check the levels of substances that could cause kidney stones, such as calcium.
It is helpful to try to urinate through some gauze or a stocking to try to collect the stone, as analysis of this will make the diagnosis easier and help find the treatment that is best for you. Ask your GP for advice.
In severe cases, you may be referred to a urologist for an x-ray, CT scan or ultrasound scan.
Kidney stones treatment
Sometimes patients are admitted to hospital for pain control and rehydration via a drip, while they wait for the stone to pass naturally.
You may be admitted to hospital with kidney stones for the following reasons:
- The pain is severe
- There is a risk of kidney failure
- Symptoms persist, despite painkillers
- You are dehydrated and vomiting too much to keep fluids down
- You are pregnant
- You are over 60 years of age
Generally, if your kidney stone(s) is less than 4mm in diameter, it can usually be passed at home while managed with painkillers. Larger stones (6 to 7 mm) may need to be broken up using ultrasound or laser energy in hospital under a sterile procedure.
Your treatment will be decided by the Urology Surgical team treating you and may include one of the following:
- Extracorporeal shock wave lithotripsy: ultrasound shock waves are sent to the stone from a machine to break it up into pieces that can be passed easily.
- Ureteroscopy: a telescope placed carefully in via the ureter to reach the stone stuck in the ureter then breaks up the stone directly, this is via implements used or laser.
- Percutaneous Nephrolithotomy: under general anaesthetic an instrument is passed through the back into the kidney, and the stone either removed or broken down with laser.
- Open surgery: this is very rare these days for kidney stones.
Kidney stones prevention tips
Prevention is important as 50 per cent of people with a kidney stone will develop further stones over the next decade. To prevent kidney stones, try the following:
✔️ Drink lots of water
The best way to prevent kidney stones is to make sure you drink plenty of water, to avoid becoming dehydrated and to stop a build-up of waste products. Tea or coffee can contribute to your fluid intake. Drink more when it’s hot or when you’re exercising, to replenish fluids lost through sweating. Aim for pale, clear, straw like urine as this will keep waste products diluted and discourage stones. Dehydration will cause darker, more concentrated urine so it is easy to see for yourself.
✔️ Dietary changes
Always eat a heathy diet and follow the dietary changes suggested by your doctor depending on the type of stone you have.
Don’t reduce the amount of calcium in your diet unless your GP or Consultant advises you to, as it is very important for maintaining healthy bones and teeth.
You may be prescribed medication to change the levels of acid or alkaline in your urine. Hypercalcuria patients may be given diuretics, low level antibiotics may be prescribed long term for struvite stone sufferers and gout medicine may be prescribed if uric acid is the cause.
However, the medication you are already on may be contributing to your kidney stones and this might be altered by your Consultant or GP.