Kidney stones are painful little stones that are created in the kidney. The kidney filters the blood and produces urine, the urine of course being what the body doesn’t want in it’s blood. The stones are made out of minerals that exist within the blood, while most of it is expelled, sometimes the minerals build up. When the mineral build up finally begins its travels down the urinary track it can be extremely painful.
There are four types of stones that can form in the kidney, calcium, uric acid, struvite, and cystine stones. Calcium stones are the most common type of kidney stone produced by too much vitamin D, or an overactive parathyroid gland. Uric acid stones can form from eating too much meat. Struvite stones form when there is too much ammonia in the urine which can happen due to a urinary tract infection, and this type of stone is more common in women. Cystine stones form when there is a high level of cystine in your urine, which is caused by a hereditry disorder called cystinuria. This last type of stone is rare and only consists of 1 out of 100 of all kidney stones.
For more info check this link out.
http://www.medicinenet.com/kidney_stone/article.htm