First of two parts on this common disorder of the urinary tract
Most form when a chemical imbalance in urine allows minerals and chemicals to crystalize
STATEN ISLAND, N.Y. - A commonly asked question in medicine is: "What are kidney stones and what causes them?"
Kidney stones are clusters of mineral crystals and other chemicals that form in urine and build up inside your kidney.
Your kidneys are two bean-shaped organs located in the upper part of your abdomen. They have the job of filtering your blood to take out waste products and excess liquid, which leave your body as urine.
The urine flows from your kidneys to your bladder through two tubes called ureters. Urine is stored in your bladder until you empty it by urinating. When you urinate, muscles in your bladder contract to push urine out of your body through another tube called the urethra.
Most kidney stones form when a chemical imbalance in urine allows minerals and other chemicals to become so concentrated that they form crystals. The crystals stick together and build up, layer by layer, on the inner surface of the kidney, gradually forming hard masses. Kidney stones can be smaller than grains of sand or as big as golf balls. They can be smooth or have jagged edges or spiky projections.
Stones composed of calcium and phosphate or calcium and oxalate are the most common. Calcium, phosphate, and oxalate are found in many of the foods you eat. Other, less common stones are made of uric acid, magnesium and ammonia, or cystine. Everyone has those chemicals and minerals in their blood and urine; however, some of them are present in higher concentrations in people who are prone to forming kidney stones.
Kidney stones affect more men than women. They usually develop in adults, but children sometimes get them too.
Some stones form in the kidney and stay there for many years without causing symptoms or any other problems. These "silent stones" usually aren't found until they are seen on an abdominal X-ray or during an ultrasound exam that is done to diagnose another problem. Stones that are very large, although they may not cause symptoms, can eventually damage the kidney. Therefore, treatment is recommended.
A kidney stone may break away from the wall of your kidney and get washed into your ureter with your urine. If the stone is smooth and very small, it will probably pass through your urinary tract and out of your body without causing any symptoms.
If the stone is large or has jagged edges or spiky projections, it might get stuck in your ureter and could cause a blockage that prevents urine from flowing freely. The muscles in the walls of the ureter will contract forcefully to try to make the stone move along. The muscle contractions can be extremely painful.
If the muscle contractions finally succeed in pushing the stone into your bladder, the pain will subside, and the stone will eventually pass out of your body when you urinate. You may feel discomfort again as the stone is pushed through your urethra, but the pain will not be as severe as it was when the stone passed through your ureter.
If, after a few days, the stone still has not dislodged and starts moving through your urinary tract, your doctor might have to break it apart or remove it to prevent complications such as urinary tract infection or kidney damage.
In next week's article there will be a discussion about the options for treatment of kidney stones.