Dear Dr Nina: 'I suffer with kidney stones. Why do they keep forming?'
Q I have had recurrent kidney stones for several years now. Why am I susceptible to them, and why do they keep forming? Is there anything I can do to prevent their formation? And is it likely that I will have to have surgery for them in the future?
A Kidney stones are small hard mineral deposits that form inside the kidneys. They can be quite common occurring in up to one in 10 adults. The majority of these stones are really small. Stones that become larger and start to pass out of the kidneys can become symptomatic causing infection, pain or, rarely, obstruction along their path out of the body.
There are several types of kidney stones, the exact way and reason they form isn't quite so clear. Calcium stones are the most common accounting for 60 to 80pc of cases.
Struvite stones may occur in association with repeated urinary tract infections. Uric acid stones may occur on those who don't drink enough fluids, eat a very high protein diet or have gout. Genetic factors may also increase the risk of these. Another genetic condition can lead to cystine stones.
Being male, middle-aged and having a family history of kidney stones makes you more susceptible. They are three times more common in men than women and occur most commonly in those aged 30 to 50. Dehydration increases the risk. It is important to produce more than one litre of urine daily to flush the kidneys through. Obesity, digestive disease and surgery may also increase the risk.
Kidney stones are associated with bouts of severe abdominal pain. This usually comes in waves and is referred to as renal colic.
The pain usually starts in the side and back and may radiate down into the groin. Other symptoms include urinary infection, blood in the urine, nausea and vomiting, a constant need to pass urine and fevers and chills.
Those who are passing larger stones will usually end up presenting to an emergency department due to the severity of the pain. If symptoms are milder you may end up with your GP. Most calcium containing stones will show on X-ray, so this basic test may help diagnose the problem. A specialised CT scan is usually required to confirm the presence and location of stones in the urinary tract.
Stone may pass themselves and the usual treatment is lots of fluids (either intravenous or by mouth) and painkillers. If a single stone is present and this passes, further treatment may not be required. If stones are large or multiple or there is any obstruction along the tract further treatment may be required. Lithotripsy is external beam shock therapy that delivers pulses of energy to the stones breaking them into pieces small enough to pass. Surgery is only more rarely required.
In order to reduce the risk of further stones it is important to drink plenty fluids upwards of two litres daily. Calcium and vitamin D supplements should be avoided in those with a history of kidney stones.