There are five types of kidney stones based upon the chemical composition of the stone, but two are usually linked together since both contain calcium. Overall, there are at least 20 chemical substances that have been reported in stones. In addition to the risk factors listed below, people who take the protease inhibitor, Indinavir, a drug used to treat HIV and AIDS, are at a risk of developing kidney stones.

Calcium Oxalate Stones & Calcuim Phosphate Stones

Calcium kidney stones account for about 70% to 80% of all stones and are comprised of calcium oxalate, insoluble phosphate salt or both. The kidneys excrete calcium that is not needed for bones and muscles. Calcium stones tend to grow no larger than 2 centimeters in size. Although pregnancy causes an increase in urine calcium excretion, pregnancy does not accelerate stone formation. Only a small percentage of those with calcium stones have an identifiable systemic disease that causes the stones. These diseases associated with them include hypercalciuria, hyperuricosuria, hypocitraturia, and hyperoxaluria. About 50% of patients with hypercalciuria, do not have any disease and present with normal serum calcium and serum parathyroid hormone.

Struvite Stones

Struvite Stones or triple phosphate stones are also called infection stones, since they often form with several episodes of urinary tract infections (UTIs) and can grow quite large. Urinary tract infections can cause debris that crystals can attach to and form stones. Certain bacteria excrete urease, which increases urine pH, making the urine more alkaline and increasing the deposition of phosphates in the urine, which can form calcium phosphate stones.

Struvite stones cause about 10% to 15% of stones, composed of magnesium-ammonium-phosphate, and they generally develop a staghorn appearance, which is jagged or branched in appearance. Struvite stones are associated with substantial morbidity, tend to show up in women with recurrent UTIs, paralyzed patients, and those with urinary tract abnormalities.

Uric Acid Stones

Uric acid kidney stones are produced when uric acid crystallizes. Men tend to have this type more commonly and usually build up uric acid in kidneys or joints. Having this in the joints can cause gout, an inherited disorder with painful arthritic symptoms. This can be caused from a diet high in purines, especially those containing organ meats and fish. Interestingly enough, gout suffers generally are more likely to produce uric acid stones, but uric acid stone suffers, do not usually have gout. This reason for this relationship between the two diseases is not understood.

Alcohol consumption may play a role particularly among those that suffer from gout. Other causes include chemotherapy for cancer, certain bone marrow disorders where blood cells are over produced and an inherited disorder called Lesch-Nyham syndrome.

Cystine Stones

Only 1% to 2% of stones are of the cystine type and tends to run in families. Cystine is an amino acid and used as one of the building blocks for muscles, nerves, and other body parts. Cystinuria is a rare genetic defect that causes excess build up of cystine in the urine. Cystine stones tend to grow large and take on a staghorn appearance also.

Treatments may vary depending on which type of stone you have. But one thing is for certain, the kidney pain associated with having stones will definitely make you want to do anything and everything you can do to prevent or avoid ever forming them.