How is a stone formed in urine?
Urine is basically made of unwanted salts in the body. Presence of a reasonable amount of water is essential to prevent stone formation. In dehydration, the salt content in the urine gets concentrated and results in precipitation of crystals. Normally the citrate content in the urine binds with calcium salt and prevents its precipitation when the urine is concentrated, however if the citrate salt content is low, the chances of forming a calcium stone is higher.
Sometimes stagnation to urine (poor urine habits or underlying problems) promotes stone formation. Rarely children with stones have birth defects that make them pass more calcium or oxalates or urates (hypercalciuria, hyperoxaluria, hyperuricosuria) and less citrate in urine. Also urine infection makes them more prone to stone formation and once the stone is formed it can promote further stone formation and infection.