What is a kidney stone analysis?

A kidney stone analysis is a test done on a kidney stone to see what chemicals are in it. The test is done on a kidney stone that has been passed in the urine or removed from the urinary tract during surgery. Chemical analysis of a kidney stone shows the type of stone which can guide treatment and give information that may prevent more stones from forming. People who have had a kidney stone have a chance of having another one, so prevention measures are important.

A kidney stone (renal calculus) forms in the kidney from substances that would normally pass out of the body in the urine. When there are large amounts of these substances, they separate from the urine and form kidney stones.

A kidney stone can be as small as a grain of sand or as large as a golf ball. Sometimes a stone may leave the kidney and move down a ureter into the bladder. From the bladder, the stone passes through the urethra and out of the body in urine. Passing a kidney stone through a ureter or the urethra may be painless, or it may cause severe pain. A kidney stone may cause other symptoms, such as blood in the urine (hematuria), pain when urinating or a severe need to urinate.

Chemical analysis of a kidney stone is performed to evaluate its composition. The composition of kidney stones may vary from a simple crystal to a complex mixture containing several different species of crystals. The composition of the center, the original crystal over which new layers form, may be entirely different from that of the outer layers. Stones are most commonly made up of calcium oxalate. Prevention of kidney stones is important. People who have had a kidney stone have a chance of forming another one. Chemical analysis of a kidney stone can:

• help determine a cause of its formation.
• guide treatment decisions.