What are the symptoms of kidney stones?
Stones are produced from chemicals which have crystallied in concentrated urine; the crystals can enlarge over time (like stalactites or stalagmites in a cave).
The symptoms and signs may include:
- No symptoms – if a stone stays in your kidney, it may not cause any symptoms at all, and may only be found found “by chance” (usually on an X-ray or scan done for another reason)
- Aching in your loin (flank)
- Non-visible blood in your urine – found only when your urine is examined under a microscope or tested using a sensitive dipstick
- Infection in your urine – stones are a known risk factor for urinary infection; or
- Ureteric colic – severe pain as a stone passes down towards your bladder from your kidney
When a stone moves down from your kidney into your ureter (the tube that carries urine from the kidney to the bladder), you may get severe pain (known as ureteric colic). This can be very unpleasant, often with nausea and vomiting. It usually starts in your loin, and may radiate down to your groin or testicle/labia as the stone moves down (pictured right).
When the stone gets close to your bladder, you may get a constant need to pass urine although there is nothing to pass; this is due to the stone irritating the base of your bladder and “fooling” it into thinking that it is full. A stone in this position can also cause:
- Burning when you pass urine
- Pain at the tip of your penis or urethra (waterpipe); and
- Visible blood in your urine
What should I do if I think I have stones?
The symptoms above are not specific to kidney stones. Similar symptoms can be caused by problems with your back or spine, and other urological or non-urological conditions. if you have any of these symptoms, you should arrange an appointment with your GP to see what further tests you may need.
Acute ureteric colic often needs urgent referral so that you can get adequate pain relief (which may require injections) and urgent imaging (usually a CT scan). This helps to decide whether your stone can be left to pass by itself, or whether you need admission to hospital. If this is your first stone episode, you may need to visit your local Accident & Emergency Department for pain relief and imaging; this helps to make the diagnosis quickly, and means we can rule out any other cause for your sudden abdominal pain.
What are the facts about kidney stones?
Kidney stones are common. They are a “chance” finding in 8% of patients (one in 12) having a CT scan, and have been steadily increasing in incidence since the early 20th century.
One in 11 people (9%) will get stone symptoms during their lifetime. Men are affected slightly more often than women, with the risk greater in Caucasians than in other ethnic groups. Patients of all ages suffer from stones, but the peak age for a first stone is around the age of 45.
There are several types of stone, grouped according to their biochemical composition:
Calcium-based stones (60 to 80% of all)
Calcium-based stones are the commonest type, and include calcium oxalate stones and calcium phosphate stones. Calcium stones are usually a mixture of both, but are mostly made from calcium oxalate (the commonest stone overall). This is probably because calcium and oxalate/phosphate are very insoluble when mixed together in urine.
Struvite stones (10 to 15% of all)
These are also known as “infection” or “triple phosphate” stones (because they are made of calcium, magnesium and ammonium phosphate). They are slightly commoner in women because of their association with urinary infection. Infections with certain bacteria convert urea (a waste product in your urine) into ammonia; this makes your urine alkaline and allows calcium phosphate to crystallise out, so that very large stones can grow, sometimes filling the whole kidney. The largest stones are known as “staghorn” calculi, and these can be the most challenging of all stones to treat.
Uric acid stones (5 to 10% of all)
These tend to have a smooth surface and golden colour. They form in acidic urine and are more common in people who eat a diet rich in animal protein. They are also seen in patients with the metabolic syndrome (see below) whose urine tends to be unusually acidic.
Cystine stones (1% of all)
Cystinuria is a hereditary condition caused by a genetic defect. Although rare, it causes stones in young patients. Cystine stones often recur and need multi-disciplinary care, not only to treat the stones, but to help prevent further ones forming (see below). If you have cystinuria, we often recommend that other members of your family are also screened for the disease.
Others (1% of all)
Other types of stone are rare. Some drugs can cause crystals to form in your urine which then grow into stones. This is sometimes seen with triamterene (a diuretic) or indinavir (an anti-HIV drug). Very rarely, stones may form from xanthine crystals; this is due to an inherited enzyme deficiency.
What treatments are available for kidney stones?
Your stone will be managed according to what is best for you, for the stone you have and for the symptoms it is causing you.
We usually have a detailed discussion with you about the best way to manage your stone(s). Treatment options range from simple observation with repeat imaging, through minimally-invasive treatments (such as shockwave lithotripsy) to surgical interventions (see below). Open surgery is rarely needed nowadays except for non-functioning kidneys caused by stones, rather than just removing the stone(s), the best treatment is to remove the whole of the kidney, by open surgery or using a “keyhole” approach.
Small stones in your kidney, found “by chance”, may only need treatment if they enlarge or cause symptoms. Active treatment, using one or more of the methods below, is likely to be recommended for stones that are:
- Causing troublesome symptoms (especially pain)
- Causing blockage to your kidney
- Causing infection (especially when coupled with blockage)
- Associated with an anatomical problem that might make further stone formation more likely
- Large enough that delayed treatment might allow the stone to grow more (requiring more invasive measures, with a risk of incomplete stone clearance)