Kidney Stones Health Article

Struvite stones

This type accounts for 10% of all kidney stones. Struvite stones are composed of magnesium ammonium phosphate. These stones occur most often in patients who have had repeated urinary tract infections with certain types of bacteria. These bacteria produce a sub-stance called urease, which increases the urine pH and makes the urine more alkaline and less acidic. This chemical environment allows struvite to settle out of the urine, forming stones.

Uric acid stones

About 5% of all kidney stones are uric acid stones. These occur when increased amounts of uric acid circulate in the bloodstream. When the uric acid content becomes very high, it can no longer remain dissolved and solid particles of uric acid settle out of the urine. A kidney stone is formed when these particles cling to each other within the kidney, slowly forming a solid mass. About half of all patients with this type of stone also have deposits of uric acid elsewhere in their bodies, commonly in the joint of the big toe. This painful disorder is called gout. Other causes of uric acid stones include chemotherapy for cancer; certain bone marrow disorders in which blood cells are overproduced; and an inherited disorder called Lesch-Nyhan syndrome.

Cystine stones

These account for 2% of all kidney stones. Cystine is a type of amino acid, and people with this type of kidney stone have an abnormality in the way their bodies process amino acids in the diet.

Patients who have kidney stones usually do not have symptoms until the stones pass into the ureter. Prior to this development, some people may notice blood in their urine. Once the stone is in the ureter, however, most people will experience bouts of very severe pain. The pain is crampy and spasmodic, and is referred to as "colic." The pain usually begins in the flank region, the area between the lower ribs and the hip bone. As the stone moves closer to the bladder, a patient will often feel the pain radiating along the inner thigh. Women may feel the pain in the vulva, while men often feel pain in the testicles. Nausea, vomiting, extremely frequent and painful urination, and blood in the urine are common. Fever and chills usually mean that the ureter has become obstructed, allowing bacteria to become trapped in the kidney and cause a kidney infection (pyelonephritis).