The most common types contain calcium salts. They begin as tiny grains, but can grow to more than an inch. Pain is the key symptom. If a large stone passes into a ureter, it can cause severe pain and spasms. The ureters are the tubes connecting the kidneys to the bladder.
Stones can block the flow of urine.
A common sign is blood in the urine. The causes of kidney stones are not always clear. Diet and fluid intake appear to be major factors. Stones seem to be more common in hot climates and during summer months. They are more common in the southeastern United States.