Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
A kidney stone is a small stone, usually made up of calcium crystals, that forms inside the part of the kidney where urine collects. The stone usually causes little problem until it falls into the ureter, the tube that drains the kidney into the bladder, and causes an obstruction, preventing urine from draining out of the kidney and often causing severe pain.
One of the roles of the kidney is to remove waste from the body by filtering blood and making urine. That urine flows from the kidney into the bladder through the ureter, a thin tube that connects the two. The bladder empties through the urethra, a tube much wider than the ureter.
A variety of minerals and chemicals are excreted in the urine and sometimes these combine to form the beginning of a stone. Over time, this can grow from an invisible speck of sand into a stone that can be an inch in diameter or larger.
There are different terms for kidney stones depending upon where they are located within the urinary tract:
Urolith: A stone anywhere within the urinary tract
It isn't exactly clear what causes kidney stones to form in some people and not others. Usually it requires concentrated urine that allows minerals like calcium to come in close contact with each other. Changes in the acid-base balance (pH) of the urine, how concentrated it is, and the concentration of minerals and chemicals within the urine are all factors that can begin the formation of a stone.
Crystals can form the beginning of the stone and eventually grow large enough to cause problems. Concentrated urine often occurs during an episode of dehydration, setting the stage for the beginning of stone formation. The consequences of that stone, when it is large enough to cause an obstruction, may occur weeks, months, or years later.
Kidney stones are small, crystalline masses that develop within the kidneys and travel out of the body via the urethra. Passing kidney stones can be very painful. Some kidney stones pass without intervention; others require medical treatment.