Kidney stones can take on a variety of shapes, sizes, textures and colors. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) describes four major types of kidney stones: calcium, struvite (or "infection"), uric acid and cystine stones. If you experience a kidney stone it will be important to determine the type of stone you are passing to determine proper treatment and future preventative measures.
Calcium Stones
Calcium stones are by far the most commonly diagnosed kidney stone, making up about 80 percent of all cases. These stones can be of various sizes and shapes and are typically very dense and cause great pain as they pass through the urinary tract. Calcium stones may become large enough to block urine flow altogether, causing further pain and distress. The pain associated with these stones is sharp and stinging and usually comes in waves as the stone passes through the urinary tract. Calcium stones form as a result of an oversaturation of calcium in the kidneys. Such excess calcium usually combines with oxalate to form dense calcium oxalate stones. An oxalate-rich diet, including foods such as chocolate, spinach, beets and chard, may increase one's chances of developing calcium stones.
Struvite Stones
Struvite stones are also known as "infection" stones, as they are formed by bacteria in the urinary tract during a urinary tract infection. These stones are formed from ammonia produced by bacteria and magnesium. Struvite stones are taken very seriously, as kidney infections can be very dangerous, especially in combination with a stone. If you experience symptoms of kidney stones in combination with symptoms of infection (nausea, fever, chills), contact your doctor immediately.
Uric Acid Stones
Uric acid stones form in individuals with overly acidic urine. Diets high in protein can increase urine acidity and help such stones to form. Obese individuals and diabetics also tend to have more acidic urine as a result of insulin resistance and are at risk for developing these types of stones. Uric acid stones are typically less dense than calcium stones and may be difficult to identify using x-rays.
Cystine Stones
Cystine stones are very rare, making up only about 1 percent of kidney stone cases. Cystine stones form in individuals that are unable to excrete the amino acid cystine as a result of a genetic defect. Individuals with a family history of cystine stones are at considerable risk of developing cystine stones. It is recommended by the NIDDK that those at risk drink several glasses of water per day and limit intake of cystine-rich and protein-rich foods.
