About Kidney Stones
Urine has many dissolved minerals and salts. Stones may form when urine has high levels of some of these minerals and salts.
Kidney stones may start small and not cause any issues at first. However, kidney stones can grow larger in size, even filling the inner hollow structures of the kidney. Some stones stay in the kidney, and will never cause any problems.
Kidney stones can travel down the ureter sometimes. (The ureter is the tube between the kidney and the bladder.) If the stone reaches your bladder, it can be passed out of the body through your urine. If the stone becomes lodged in the ureter, it blocks urine flow from that kidney. This may be painful.
The Kidneys and Urinary System
The kidneys are fist-size organs that handle the body's fluid and chemical levels. Most people have two kidneys, one on each side of the spine behind the liver, stomach, pancreas and intestines. Healthy kidneys clean waste from the blood and remove it in the urine.
When your kidneys are healthy, they properly control the levels of sodium, potassium and calcium in the blood.
The kidneys, ureters and bladder are part of your urinary tract. The urinary tract makes, moves, and stores urine in the body. The kidneys make urine from water and your body's waste. The urine then travels down the ureters into the bladder, where it is stored. Urine leaves your body through your urethra.
Kidney stones form in the kidney. If a stone leaves the kidney and gets stuck in the ureter, it is called a ureteral stone.
What are Kidney Stones Made of?
Kidney stones come in many different types and colors. The way your kidney stones will be treated depends on the type of stone you have. The path to prevent new stones from forming will also depend on your stone type.
Calcium stones (80 percent of stones)
Calcium stones are the most common type of kidney stone. There are two types of calcium stones:
- calcium oxalate, and
- calcium phosphate
Calcium oxalate is by far the most common type of calcium stone. Some people have too much calcium in their urine, raising their risk of calcium stones. Even with normal amounts of calcium in the urine, calcium stones may form for other reasons.
Uric acid stones (5-10 percent of stones)
Uric acid is a waste product that comes from chemical changes in the body. Uric acid crystals do not dissolve the right way in acidic urine. This causes a uric acid stone. Having acidic urine may come from:
- Being overweight
- Chronic diarrhea
- Type 2 diabetes (high blood sugar)
- Gout
- A diet that is high in animal protein and low in fruits and vegetables
Struvite/infection stones (10 percent of stones)
Struvite stones are not a common type of stone. These stones are related to chronic urinary tract infections. People who get chronic UTIs, or people with poor bladder emptying due to neurologic disorders are at the highest risk for developing these stones.
Source: Urology Care Foundation: The Official Foundation of the American Urological Association