Kidney stone disease can be a frightening, dangerous and painful condition. Kidney stones form as certain metabolites build up in the kidneys and urinary tract, forming solid deposits that eventually break off as independent stones. Kidney stones are classified by the type of material from which they are composed as well as the underlying medical condition that promotes their formation. The specific classification of kidney stone type will determine a proper course of treatment and direct future prevention.
Calcium Kidney Stones
According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), about 80 percent of kidney stones are calcium kidney stones. Calcium kidney stones are dense and can take on a variety of shapes, sizes and textures. While these stones can form at any point in life, men over the age of 50 are most likely to experience these types of stones. Calcium kidney stones form as calcium builds up in the kidneys and urinary tract. This is often the result of a genetic condition known as hypercalciuria in which the body absorbs too much calcium and fails to excrete calcium. Calcium kidney stones can be further classified as calcium oxalate (CaO) kidney stones or calcium phosphate (CaP) stones depending on the form of calcium from which they are made. The vast majority of calcium kidney stones are calcium oxalate stones that have some minor component of calcium phosphate. Pure calcium phosphate stones lacking oxalate are very rare. Dietary sources of oxalate such as spinach, beets and chocolate can contribute to calcium stone formation.
Struvite or "Infection" Stones
Struvite stones, also known as "infection" stones, occur in individuals with an infection of the kidney and represent about 10 percent of kidney stone occurrence. According to the Mayo Clinic, these stones are primarily composed of magnesium that builds up in the kidneys and urinary tract as a waste product of bacteria infecting the kidneys. Symptoms of struvite stones are similar to those of a kidney infection and include fever, chills, nausea, abdominal pain, trouble urinating and bloody or cloudy urine. Struvite stones can be very dangerous and painful and should be treated with urgency. Struvite stones are almost always treated with a course of antibiotics. While men are most at risk for kidney stones in general, women are more at risk for struvite stones as women are more likely to experience kidney infections.
Cystine Stones
Cystine stones are very rare, making up about 1 percent of kidney stone cases. According to the NIDDK, individuals with this condition have a rare genetic disorder that prevents the excretion of the amino acid cystine. As cystine builds up in the kidneys and urinary tract, it forms solid cystine stones. While there is no ideal treatment for cystine kidney stones, the NIDDK and the Mayo Clinic suggest that individuals with this condition drink plentiful fluids and avoid high-protein foods rich in cystine to help prevent the formation of cystine stones.
