KIDNEY STONES

Symptoms of kidney stones

Symptoms usually occur if the kidney stone:

• Gets stuck and blocks the kidney.
• Starts to travel down the ureter (the tube that attaches each kidney to the bladder) – the ureter is narrow and the kidney stone causes pain as it tries to pass through.
• Causes an infection.

In these cases, common symptoms of kidney stones include:

• Periods of extremely intense pain in the back or side of your abdomen or occasionally in your groin, which may last for minutes or hours. This tends to occur in waves and is called renal colic. It usually comes on rapidly and is 10/10 in severity.
• Feeling restless and unable to lie still.
• Nausea (feeling sick).
• Needing to urinate more often than normal.
• Blood in your urine – this may be caused by the stone scratching the kidney or ureter.

Blocked ureter associated with a kidney infection

Rarely, if a stone blocks the ureter, this can lead to a kidney infection and pus building up in the kidney. This is a medical emergency.

Symptoms may include:

• Severe loin pain.
• A high temperature (fever) of 38°C (100.4°F) or over.
• Shivering.
• Chills.
• Feeling very weak or tired.
• Diarrhoea.
• Cloudy and bad-smelling urine.

If you develop renal colic you will need to attend A+E so that analgesia can be given and a diagnosis made.

Kidney stones

Kidney stones are hard mineral deposits that form inside the kidneys.

This build-up may consist of:

• Calcium (most common).
• Uric acid (a waste product produced when the body breaks down food to use as energy).
• Cystine (an amino acid that helps build protein).
• Drugs eg. Indinavir (HIV medication).

Quick Facts;

• Affects approximtaely 3% of the population.
• More common in men.
• More common in industrially developed nations.
• More common in certain professions where fluid intake is poor eg. Chefs, taxi drivers.
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• Recurrence is common
  • 10% in 1 year
  • 40% in 3 years
  • 75% in 10 years
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You are at a greater risk of developing recurrent (returning) kidney stones if:

• You eat a high-protein, low-fibre diet (avoid protein drinks).
• You are inactive or bed-bound.
• You suffer with recurrent urinary tract infections.
• You have a genetic disease such as Cystinuria.
• You have had an intestinal bypass (surgery on your digestive system) or a disease of the small intestine, such as Crohn's disease (inflammation of the gut).
• You take certain medications eg. Calcium and vitamin D supplements.

Types of kidney stones

Kidney stones can develop as a result of a number of different factors. The causes of the four main types of kidney stone are outlined below.

1) Calcium stones

Calcium stones are the most common type of kidney stone. They are caused when there is too much calcium in the urine. High amounts of calcium could be a result of:

• An inherited condition called hypercalciuria which leads to large amounts of calcium in urine.
• High levels of vitamin D.
• An overactive parathyroid gland (your parathyroid glands help to regulate the amount of calcium in your body).
• Kidney disease.
• A rare disease called sarcoidosis.
• Some cancers.

Calcium stones are usually very hard.

2) Struvite stones

Struvite stones are often caused by recurrent urinary tract infections.

They are more common in women than in men.

They can form very large stones that fill the entire kidney. These are called "staghorn" stones. They tend to from slowly over time and are not really painful. Patients may just notice a dull ache in their back or loins.

3) Uric acid stones

Uric acid stones often form when there is a high amount of acid in your urine.

Dalmations are the only other animal to get uric acid stones.

Uric acid stones may be caused by:

• Eating a high protein diet that includes lot of meat.
• A condition such as gout that prevents the body breaking down certain chemicals.
• An inherited condition that causes higher levels of acid in the body.
• Chemotherapy (a treatment for cancer).

4) Cystine stones

Cystine stones are the rarest form of kidney stone.

They are caused by an inherited condition called Cystinuria, which affects the amount of Cysteine that passes into the urine.

Treatment often involves surgery to clear the stones and then medication to try and stop them re-forming.

Diagnosing kidney stones

• Urine tests - this is to look for:
  • Small traces of blood - this may be a sign that stones are present. They may rub against the lining of the urinary tract and cause small amounts of blood to appear in the urine.
  • Signs of infection.
  • Crystals of stone may also be visible.
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• Blood tests - this is to check:
  • That the kidneys are working properly.
  • That the level of calcium and uric acid in the blood which are common constituents of stones are normal.
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• Imaging tests - this is to look for stones in the kidneys or ureter.
  • Computerised Tomography (CT) scan – this takes a series of X-rays of your body at slightly different angles and uses a computer to put the images together. It is the best way to look for stones, especially if they are small. The test is associated with a low dose of radiation. No contrast is used.
  • X-ray – this is a useful test to keep an eye on the size of kidney stones. Most stones made of calcium will show up on X-rays though other stones will not.
  • Ultrasound Scan – this uses high frequency sound waves to look for stones. There is no radiation associated with this test. It is very dependent on the person who performs it and often it overestimates the size of stones.
  • Intravenous Urogram (IVU) or Intravenous Pyelogram (IVP) – an X-ray is initially taken to try and identify the stone and then dye is injected into a vein. This shows up on a repeat X-ray and highlights any blockages as the kidneys filter the dye out of your blood and into your urine. This test has largely been replaced by CT.
  • MRI Scan - this is very rarely used to look for stones or kidney obstruction as stones are poorly seen on MRI. There is a role in pregnant women who have loin pain and no diagnosis has been made. It avoids the risk of radiation to the unborn child.

You can try and collect your kidney stone if it passed by urinating through some gauze or a stocking. This will allow the stone type to be analysed and allow more tailored advice to be given about lifestyle changes to prevent further stone formation in the future.

Treating ureteric stones

Conservative:

If the stone is small (<4mm), the pain has settled and your blood tests are normal there is a chance that the stone will pass by itself without any need for intervention.

You will be given:

• An alpha blocker eg. Tamsulosin - this helps to relax the ureter tube and increase the chance of you passing the stone
• Painkillers:
  • Diclofenac - is an extremely good pain killer for renal colic especially if administered rectally. It should be avoided if you have asthma, renal failure or stomach ulcers. 

If the pain returns and is not controlled by pain killers or if you develop a fever you will need to contact me urgently or return to Accident and Emergency for further treatment.

You should maintain a high fluid intake and try and filter the urine with gauze to look for the kidney stone.

Usually after 4 weeks we will repeat a scan to make sure that the stone has passed by itself. Even if the symptoms settle this does not mean that the stone has gone. You may not even notice the stone passing out in the urine, especially if it is small.

Cystoscopy and insertion of JJ stent

A JJ stent is a thin piece of hollow plastic that has curls at each end. It is usually placed as an emergency procedure to unblock a kidney due to some form of obstruction in the ureter (tube that drains urine from the kidney into the bladder). It is inserted under a general anaesthetic using an endoscopic technique. A telescope is placed into the bladder and a wire passed into the kidney under X-ray screening control. The stent is the deployed over the wire. The top end of the stent will form a curl in the kidney and the bottom end a curl in the bladder, these help to hold the stent in place. Once things have settled and the ureter has had time to dilate around the stent a further procedure will be planned to deal with the stone.

Side effects of the stent:

• Blood in the urine - especially when undertaking heavy exercise.
• Pain when passing urine.
• Increased urinary frequency - this is where the stent rubs on the lining of the bladder.

Extracorporeal shock wave lithotripsy (ESWL)

It involves using X-rays or ultrasound to pinpoint the position of the stone. A machine then produces sound waves to fragment the stone into smaller pieces so it can be passed in your urine.

ESWL can be an uncomfortable though is usally well tolerated. It feels like an elastic band is being flicked against the skin.

It usually requires several treatments to clear a stone.

Possible side effects:

• Common
  • Blood in the urine for a short time after treatment.
  • Renal colic and pain in the loin as fragments pass.
  • Failure to localise the stone and therefore give treatment.
  • Failure to break the stones if they are hard.
  • Failure to pass the fragments of stone.
  • Multiple treatments.
  • Recurrence of stones.
  • Bruising of the skin.
  • Urinary tract infection.
• Rare (<1 in 50)
  • Severe infection requiring admission to hospital.
  • Bruising around the kidney requiring intervention such as placement of a drain.
  • Fragments getting stuck in the ureter requiring intervention.
  • Damage to surrounding organs such as the pancreas.

Semi-rigid ureteroscopy

If a kidney stone is stuck in your ureter (tube that carries waste products from your kidneys to your bladder) you may need to have ureterorenoscopy. This involves being taken to theatre and given a general anaesthetic. A long, thin telescope called a ureteroscope is then passed through your urethra (the tube urine passes through out of the body) and into your bladder. It is then passed up into your ureter to where the stone is stuck. If possible, the stone is broken with a laser and the fragments removed. You will most likely end up with a JJ stent in after the procedure which will require another small opeartion which can be performed under a local anaesthetic to remove it. 

Percutaneous nephrolithotomy (PCNL)

PCNL is a procedure that is usually reserved for larger stones (>1.5cm) or those in a walled off area within the kidney called a diverticulum.

PCNL can be performed with the patient lying on their front (prone) or on their back (supine). I am one of a selected number of surgeons in London who can perform the latter procedure. This has significant anaesthetic advantages as it puts less strain on a patient's heart and lungs whilst they are under anaesthetic.

A thin telescopic instrument called a nephroscope is inserted into the kidney via a 1cm incision. Guiding the position of the kidney puncture is performed by a radioogist using both ultrasound and X-ray guidance. The stone is either removed intact using graspers or broken into smaller pieces using pneumatic energy.

Open surgery

Nowadays, it is rare for people to have open surgery for kidney stones (<1% of cases require this type of surgery). It is usually used if there is a very large stone or abnormal anatomy.

Preventing kidney stones

The best way of preventing kidney stones is to make sure you drink plenty of water each day to avoid becoming dehydrated.

It is very important to keep your urine dilute to avoid waste products forming into kidney stones.

You can tell how dilute your urine is by looking at its colour. The yellower your urine is, the more concentrated it is.

Your urine is usually a dark yellow colour in the morning because it contains a build-up of waste products that your body has produced overnight. After the first void all other urine should be colourless.

Fluid intake will depend on the environment and each individual patient. Aiming at two litres per day is reasonable. Drinks such as tea, coffee and fruit juice can count towards your fluid intake but water is the healthiest option and is best for preventing kidney stones.

It may be sensible to have 1l of water when you get out of bed with a fresh lemon squeezed into it. This will help to hydrate the body and fresh lemon contains Citrate which helps prevent stone formation.

You should also make sure that you drink more when it is hot or when you are exercising to replenish fluids lost through sweating.

Diet

If your kidney stone is made up of calcium oxalate, you may be advised to reduce the amount of oxalate in your diet.

You should continue to eat foods containing calcium as this prevents oxalate being absorbed into the body and stones forming

Foods that contain high levels of oxalate include:

• Beetroot
• Asparagus
• Rhubarb
• Chocolate
• Berries
• Leeks
• Parsley
• Celery
• Almonds, peanuts and cashew nuts.
• Soy products
• Grains, such as oatmeal, wheat germ and wholewheat.
• Tea (so if you are having tea it should always have milk added to it).

You should also avoid:

• Foods which are rich in animla protein.
• Foods which are high in salt.

Medication

Medication can be used in certain circumstances to try and prevent kidney stone recurrence.

For example, if you have:

• Calcium stones – you may be prescribed a diuretic medication if they are caused by hypercalciuria(an inherited condition).
• Struvite stones – you may be prescribed antibiotics to help prevent urinary tract infections or kidney infection, which are the main causes of struvite stones.
• Uric acid stones – you may be prescribed Allopurinol (a medication used to lower uric acid levels) and medication to help alkalise your urine.
• Cystine stones – you may be prescribed medication to lower levels of cystine in your urine.