What should I do if I think I have kidney stones?
If you have pain in your loin, especially if you also have other urinary symptoms or features suggesting an infection in your urine, you should contact your GP for further advice
Whilst kidney stones (pictured) may cause pain in the loin with radiation down into your groin, there are many other causes for such pain. These include problems with your back and spine as well as a number of other non-urological conditions. The only way to find the cause of your symptoms is to have further investigations with your GP.
What are the facts about kidney stones?
- Kidney stones are found in 2-3% of people and 0.5% of people present each year with an acute episode of pain due to stones; These rates have been rising steadily since the start of the 20th century;
- Men are more commonly affected than women. After the age of 50 when the sex distribution becomes equal;
- At the age of 70, you have a lifetime risk of 1 in 8 for forming a stone;
- Stones are responsible for more than 12,000 hospital admissions each year;
- Stone formation is governed by both intrinsic (heredity, age & sex) and extrinsic factors (geography, climate, water intake & diet);
- Poor fluid intake combined with a low-roughage, high protein diet containing a lot of refined sugar increases the risk of forming stones;
- There is an association with the "metabolic syndrome" (Syndrome X); and
- Recurrence rates for stones are high (20% at 5 years, 35% at 10 years & 70% at 20 years).
What should I expect when I visit my GP?
Your GP should work through a recommended scheme of assessment for suspected kidney stones. This will normally include one or all of the following:
1. A full history
Your GP will take a full clinical history, including asking about your diet, time spent in a hot dry climate, your fluid intake and whether there is a family history of stones
2. A physical examination
A full physical examination, including assessment of your abdomen, will normally be performed and your blood pressure may be taken as part of the assessment.
3. Additional tests
The usual tests performed are:
a. General blood tests
The actual tests performed will be left to your GP's discretion. It is normal to measure kidney function, liver function, blood sugar, uric acid, bone function (calcium levels) and to check the blood for anaemia or other problems
b. Urine tests
Your urine will normally be tested for blood (90% of patients with a stone have a trace of blood in the urine) and the pH (acidity) measured. A specimen may be sent to the laboratory to screen for infection and to measure a specific chemical called cystine.
24-hour urine output collections (pictured) will also be arranged for more detailed chemical analysis If:
- you are less than 30 years old;
- have a family history of stones; and
- have had stones within the previous 5 years.
c. Other specific tests
The best way to diagnose stones is to have a CT scan. Your GP may be able to arrange this for you. If not, your GP will arrange referral to a urology unit where the scan can be arranged. Almost all stones show up on a CT scan.
What could have caused my kidney stones?
There are many causes of kidney stones and it is unusual to have just one causative factor
The main reasons for forming stones are:
- Anatomical (structural) abnormalities (inherited or acquired);
- Excess stone-forming substances in the urine;
- Lack of stone inhibitors in the urine;
- Chronic Infection in the urine (mostly in post-menopausal women); and
- Idiopathic (meaning that no reason is identified in 5-10%).
In most patients, more than one of the groups above is involved in stone formation. Where no cause is identified, the stones are usually made of calcium oxalate. Recurrence of calcium oxalate stones is common.
What treatments are available for this problem?
Small stones in the kidney or ureter, which are causing no problems, can be managed expectantly and may pass spontaneously. Active treatment is usually recommended for larger stones or stones which are causing problems
You will normally be given specific advice about changes to your diet and fluid intake which will reduce the risk of further stone formation. There is some evidence that stone inhibitor levels (especially citrate) can be increased by drinking fresh lemon juice in water. This reduces the levels of stone-forming chemicals in your urine.
Download dietary advice for stone patients.
You should not restrict your calcium intake. Installing a water softener is not helpful in preventing further stones. Avoid grapefruit juice (pictured), vitamin D tablets and vitamin C supplements which can increase your risk of forming stones.
Thiazide diuretics and other drugs may be used to reduce the calcium levels in your urine.
it may be possible to dissolve certain less common types of stone using drugs but this is only appropriate for
- cystine stones: tiopronin or d-penicillamine; and
- uric acid stones: by alkalinising your urine.
If you have a stone caused by infection, you will be prescribed antibiotics before stone treatment and you may be asked to continue them after surgery.
You may be given further advice about specific medical treatment once your stone has been analysed chemically.
Small, symptomless stones in the kidney can be monitored by regular checks with an X-ray. Stones of a similar size in the ureter (less than 5mm diameter) usually pass by themselves but active treatment will be recommended if the stone shows no sign of passage after 2-3 weeks.
If you are found to have a stone in the ureter, muscle-relaxant drugs (e.g. Tamsulosin, Nifedipine) and drugs which relieve muscle spasm (e.g. Buscopan, Probanthine) are no longer used because they have little effect on symptoms and do not speed stone passage.
Extracorporeal shockwave lithotripsy - ESWL
This is the most common treatment recommended for stones in the kidneys and for stones less than 1cm diameter in the upper ureter (the drainage tube between kidney & bladder). 90% of stones will clear with one treatment but some patients may need re-treatment or even surgical intervention. If your stone does not responded to two successive treatments with ESWL, it is unlikely to fragment with further treatments and other removal methods should then be considered.
ESWL cannot be performed safely in
- pregnant women;
- patients on heparin, Warfarin or other blood-thinning agents; and
- patients whose weight exceeds 300lb.
The main reasons for recommending surgical treatment are:
- a stone which is too large to pass spontaneously (greater than 5mm diameter);
- a stone which is causing obstruction to urine drainage;
- a stone which is causing (or has been caused by) infection;
- a stone which has formed as a result of an anatomical (structural) problem which also needs correction at the same time as stone treatment; and
- failure of simple painkillers to control symptoms.
Percutaneous (keyhole) surgery (PCNL)
This is used for large stones in the kidney upper ureter, either as a primary measure or if ESWL has failed.
Flexible uretero-renoscopy (fURS)
Smaller stones in the kidney can be extracted or fragmented with a laser, using a flexible telescope passed through your bladder. You may have a temporary stent inserted after this procedure. Download the information leaflet about ureteric stents
Rigid ureteroscopy (URS)
Stones in the ureter can be extracted or fragmented with a laser (pictured), using a rigid telescope passed through your bladder. You may have a temporary stent inserted after this procedure.
Insertion of an ureteric stent
In the emergency situation, when a stone is blocking the ureter completely, it may be necessary to insert a stent under general anaesthetic to relieve the blockage so that definitive treatment can be performed at a later stage.
Percutaneous nephrestomy tube insertion
If there is a blockage with severe infection due to a stone in the ureter, a drainage tube may be inserted into your kidney under local anaesthetic to relieve the problem. This will be followed, at a later date, by definitive treatment of the stone.
What is the "bottom line"?
The best treatment for any stone is a judicious combination of all the techniques described above, tailored to the specific needs of individual patients and their individual stone(s).
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