Kidney stones (also called renal calculi, nephrolithiasis or urolithiasis) are the hard deposits made of minerals and salts that form inside the kidneys. Kidney stones form when your urine contains more crystal-forming substances – such as calcium, oxalate and uric acid – than the fluid in your urine can dilute. At the same time, your urine may lack substances that prevent crystals from sticking together, creating an ideal environment for kidney stones to form.
Each year, more than half a million people go to emergency rooms for kidney stone problems. It is estimated that one in ten people will have a kidney stone at some time in their lives. Diet, excess body weight, some medical conditions and certain supplements and medications are among the many causes of kidney stones. Kidney stones can affect any part of your urinary tract – from your kidneys to your bladder.
A kidney stone usually will not cause symptoms until it moves around within your kidney or passes into your ureters (the tubes connecting the kidneys and the bladder. If it becomes lodged in the ureters, it may block the flow of urine and cause the kidney to swell and the ureter to spasm, which can be very painful. Pain can also be accompanied with fever, nausea and vomiting. Other symptoms are presence of blood in urine or urine that smells bad or looks cloudy.