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. This may be because hot weather leads to body fluid loss. It may also be due to regional diet. People with gout can have kidney stones made from uric acid. Stones are more common in men, but rare in children and African-Americans.