A reader asks: I’ve had several urinary infections recently. The last one was quite severe, with pain in my kidney. Though it cleared up with antibiotics, the scan my doctor arranged has shown I have a small stone in my kidney. I’m waiting now to see a specialist, but am wondering why it developed and whether I’m likely to need surgery?
Dr Rosemary Leonard replies: The kidneys filter the blood and remove excess water and waste chemicals into the urine. Most of these are dissolved, but some chemicals form tiny crystals which may clump together to form a small stone. Most stones are made out of calcium and though occasionally they are linked to a raised blood calcium level, but in most cases there is no obvious reason why they form.
Though small stones often pass of their own accord, especially if you drink plenty of water, larger stones can damage the kidney, cause blood in the urine and increase the risk of a kidney infection.
There are several options for treating larger stones. The most commonly used methods are extracorporeal shock wave lithotripsy, which uses high energy shock waves to break up the stones, or if the stone is in the ureter (the passage between the kidney and the bladder) a thin telescope can be passed up into via the bladder and then a laser used to break up the stone. The fragments are then passed out in the urine.
Alternatively, a thin telescope can be passed through the skin and into the kidney, the stone is then crushed and the fragments removed. Surgery to remove kidney stones is now rarely necessary, though may be needed for very large stones.
About half of people who have a kidney stone develop another one at some time in their life, but you can help prevent this by drinking plenty of water each day, which prevents dehydration and keeps the urine dilute.
If you have a health question for Dr Leonard, email her in confidence at yourhealth@express.co.uk. She regrets she cannot enter into personal correspondence or reply to everyone