Kidney stone, or renal calculi, is a hard, crystalline mineral material. As the kidneys filter waste from the blood, they create urine. Sometimes, salts and other minerals in urine stick together to form small kidney stones. Kidney stones usually originate in your kidneys, but can develop anywhere along your urinary tract. The urinary tract includes the kidneys, ureters, bladder and urethra.
Kidney Stone Sizes
Kidney stones range from the size of a sugar crystal to a ping pong ball, but they are rarely noticed unless they cause a blockage. They may cause intense pain if they break loose and push into the ureters, the narrow ducts leading to the bladder.
Types of Kidney Stones
Kidney stones are not made up of the same crystals. The different types of kidney stones include:
Calcium stones are the most common. They can be made of calcium oxalate, phosphate, or maleate. Eating fewer oxalate-rich foods can reduce your risk of developing this type of stone. High-oxalate foods include potato chips, peanuts, chocolate, beets and spinach.
This type of kidney stone is more common in men than in women. They can occur in people with gout or those going through chemotherapy. This type of stone develops when urine is too acidic. A diet rich in purines can increase urine’s acidic level. Purine is a colorless substance in animal proteins, such as fish, shellfish and meats.
Cystine stones are rare. They occur in both men and women who have the genetic disorder cystinuria. With this type of stone, cystine – an acid that occurs naturally in the body – leaks from the kidneys into the urine.
This type of stone is found mostly in women with urinary tract infections. These stones can be large and cause urinary obstruction. These stones are caused by a kidney infection. Treating an underlying infection can prevent the development of struvite stones.