Kidney stones

What are they?

Waste products from the blood can occasionally form crystals in urine and collect inside the kidneys. Over time, they may build up to form a hard stone-like lump.

This is more likely to happen if you don’t drink enough fluids, if you’re taking some types of medication, or if you have a medical condition that lifts levels of certain substances in your urine.

Kidney stones can develop in one or both kidneys and most often affect people aged 30 to 60, with around three in 20 men and two in 20 women being affected.

What are the symptoms?

Small kidney stones may go undetected and be passed out painlessly in urine. But it’s fairly common for a stone to block a ureter, the tube connecting the kidney to the bladder, on its way out of the body.

A blockage can cause one of the severest pains ever felt (renal colic) in the abdomen or groin, and sometimes causes a urinary tract infection too.

What’s the treatment?

Most kidney stones are small enough to be passed in your urine, and symptoms can be treated at home with medication.

Larger stones may need to be broken up using ultrasound or laser energy. Occasionally, keyhole surgery may be needed to remove very large kidney stones.

Outlook and prevention

It’s estimated that up to half of people who’ve had kidney stones get them again within five years.

To avoid that, drink plenty of water. It’s very important to keep your urine diluted to prevent waste products forming into stones.