Kidney Stones

Kidney stones are stone-like lumps that can develop in one or both of the kidneys.
The medical name for stones in the kidneys is nephrolithiasis. If the stones cause severe pain, this is known as renal colic.

Kidney stones
The waste products in the blood can occasionally form crystals that collect inside the kidneys. Over time, the crystals may build up to form a hard stone-like lump. Read more about the causes of kidney stones.
After a kidney stone has formed, your body will try to pass it out of the body in urine. This means it will often travel through the urinary system (the kidneys, kidney tubes and bladder).
Small stones may be passed out painlessly in the urine and may even go undetected. However, it is fairly common for a stone to block part of the urinary system, such as the ureter (the tube connecting the kidney to the bladder) or the urethra (the tube through which urine passes out of the body). If this happens, it can cause severe pain in the abdomen or groin and sometimes causes a urinary tract infection (see symptoms of kidney stones for more information).

How common are kidney stones?
Kidney stones are quite common and usually affect people aged 30–60 years of age. They affect men more than women. It is estimated that renal colic affects about 10–20% of men and 3–5% of women.