Kidney stones are composed of various salts or mineral crystal deposits and form on the inner surfaces of the kidney. The formation of kidney stones is actually a disease process, which occurs gradually over time. More than a million Americans are hospitalized each year for the treatment of stones. Kidney stones are most prevalent in people age 20 to 50, are more common in men, and are most prevalent in Caucasians. Most stones are formed and excreted singly.
Kidney stones come in virtually any color,though most are yellow to brown.
They also come in a variety of shapes and sizes. The composition of the stone may tell something about how it is formed. Significant pain is usually the first symptom of a kidney stone. When a stone moves from the kidney into the ureter, pain can develop suddenly. If the stone is too large to pass easily, the severe, constant pain continues as the muscles in the walls of the ureter try to squeeze the stone along into the bladder.