A kidney stone, also called renal lithiasis, is a small, hard mass that develops in the kidneys. Kidney stones may be composed of a variety of minerals and acid salts, but the most common kidney stone forms when the substances calcium and oxalate come together, according to the Mayo Clinic.
Physiology
The kidneys remove excess water and wastes from the blood. They are responsible for keeping salts, fluids and other substances in the blood in balance. In normal circumstances, urine contains chemicals that keep all substances in the urine in a solution. A kidney stone forms when chemicals are absent or do not work properly and crystals separate from the urine. Most kidney stones form from a substance called calcium oxalate. This occurs when calcium in the body comes into contact with oxalate, which is present in a variety of foods and is produced by the liver.
Symptoms
Most people with a kidney stone do not experience symptoms until the stone blocks the passage of urine through the ureter, which is a thin tube that carries urine from the kidneys to the bladder. When the kidney stone blocks the ureter, it can cause severe pain, pain during urination, changes in urine color, nausea, vomiting and an increased need to urinate. If the kidney stone causes an infection, it may also cause fever and chills.
Treatment
Treatment for small stones usually consists of an increase in water intake and pain relievers. The excess amount of water can help flush out the urinary tract and remove the kidney stones in the urine. Larger stones that cannot pass on their own usually require more invasive treatment. Treatment for larger stones involves procedures that use sound waves to break apart the stones or surgery to physically remove the stones.
Prevention
The Mayo Clinic recommends making lifestyle changes to help reduce the risk of developing calcium oxalate kidney stones. One of the most important changes is to avoid foods that are rich in oxalate. Other changes include drinking water throughout the day, eating less salt and animal protein and avoiding calcium supplements.
Foods With Oxalate
Foods that contain high amounts of oxalate include beets, chocolate, peanuts, rhubarb, spinach, sweet potatoes, swiss chard and wheat germ. Foods that are considered medium-oxalate foods include celery, grapes, green pepper, grits, liver, marmalade, red raspberries and strawberries, according to the National Kidney and Urologic Diseases Information Clearinghouse.
