Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.
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.
The kidney acts as a filter for blood, removing waste products from the body and making urine. It also helps regulate electrolyte levels that are important for body function. Urine drains from the kidney through a narrow tube called the ureter into the bladder. When the bladder fills and there is an urge to urinate, the bladder empties to the outside through the urethra, a much wider tube than the ureter.
In some people, chemicals crystallize in the urine and form the beginning, or nidus, of a kidney stone. These stones are very tiny when they form, smaller than a grain of sand, but gradually can grow over time to 1/10 of an inch or larger. Urolithiasis is the term that refers to the presence of stones in the urinary tract, while nephrolithiasis refers to kidney stones and ureterolithiasis refers to stones lodged in the ureter. The size of the stone doesn't matter as much as where it is located and whether it obstructs or prevents urine from draining.
When the stone sits in the kidney, it rarely causes problems, but when it
falls into the ureter, it acts like a dam. As the kidney continues to function
and make urine, pressure builds up behind the stone and causes the kidney to
swell. This pressure is what causes the pain of a kidney stone, but it also
helps push the stone along the course of the ureter. When the stone enters the
bladder, the obstruction in the ureter is relieved and the symptoms of a kidney
stone are resolved.
While kidney stones and renal colic probably cannot be prevented, the risk of forming a stone can be minimized by avoiding dehydration. Keeping the urine dilute will not allow the chemical crystals to come out of solution and form the beginning nidus of a stone. Making certain that the urine remains clear and not concentrated (dark yellow) will help minimize stone formation.
Medication may be prescribed for certain types of stones, and compliance with taking the medication is a must to reduce the risk of future episodes.