About Kidney Stone Analysis

Kidney stones are concentrated mineral deposits that form in the kidneys when the urine is unable to dissolve the waste materials. Analysis of a stone determines its composition.

Importance

• Analysis of all kidney stones is important, regardless of their size. Analysis gives the urologist and the patient important information that can help prevent additional stones from forming.

Collection

• The doctor or lab provides a strainer to catch the stone. The patient uses the strainer during each urination and examines it afterward for the stone, which may be as small as a grain of sand.

Preparation

• The patient places the collected stone loosely in a clean dry container or plastic bag and then delivers it to the lab. Before analyzing the kidney stone, the lab will remove any blood and tissue present.

Extraction

• In some cases, the kidney stone does not pass and the urologist must extract it. This involves testing to locate and size the stone and determine the proper course of action.

Types

• According to Quest Diagnostics, most kidney stones--approximately 80 percent--contain calcium, as either calcium oxalate, calcium phosphate or a combination. Another 10 to 15 percent of kidney stones consist of magnesium ammonium phosphate, also known as struvite, while 5 to 10 percent are uric acid stones. Less than 1 percent of stones are cystine.