Kidney Stones

Kidney Stones

• Kidney Stones Overview
• Kidney Stones Causes
• Kidney Stones Symptoms
• When to Seek Medical Care
• Exams and Tests
• Kidney Stones Treatment
• Self-Care at Home
• Medical Treatment
• Next Steps
• Follow-up
• Prevention
• Outlook
• Synonyms and Keywords
• Authors and Editors
• Pictures of Kidney Stones - Slideshow

Kidney Stones Overview

The kidney acts as a filter for blood, removing waste products from the body and helping regulate the levels of chemicals important for body function. The urine drains from the kidney into the bladder through a narrow tube called the ureter. When the bladder fills and there is an urge to urinate, the bladder empties through the urethra, a much wider tube than the ureter.

In some people, the urine chemicals crystallize and form the beginning, or a nidus, of a kidney stone. These stones are very tiny when they form, smaller than a grain of sand, but gradually they can grow to a quarter inch or larger. The size of the stone doesn't matter as much as where it is located.

When the stone sits in the kidney, it rarely causes problems, but should it fall into the ureter, it acts like a dam. The kidney continues to function and make urine, which backs up behind the stone, stretching the kidney. This pressure build up 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.

Kidney Stones Causes

There is no consensus as to why kidney stones form.

• Heredity: Some people are more susceptible to forming kidney stones, and heredity certainly plays a role. The majority of kidney stones are made of calcium, and hypercalciuria (high levels of calcium in the urine), is a risk factor. The predisposition to high levels of calcium in the urine may be passed on from generation to generation. Some rare hereditary diseases also predispose some people to form kidney stones. Examples include people with renal tubular acidosis and people with problems metabolizing a variety of chemicals including cystine (an amino acid), oxalate, (a type of salt), and uric acid (as in gout).
  
  
• Geographical location: There is also a geographic predisposition in some people who form kidney stones. There are regional "stone belts," with people living in the Southern United States, having an increased risk. This is likely because of the hot climate, since these people can get dehydrated, and their urine becomes more concentrated, allowing chemicals to come in closer contact and begin forming the nidus of a stone.
  
  
• Diet: Diet may or may not be an issue. If a person is susceptible to forming stones, then foods high in calcium may increase the risk, however if a person isn't susceptible to forming stones, nothing in the diet will change that risk.
  
  
• OTC products: People taking diuretics (or "water pills") and those who consume excess calcium-containing antacids can increase the amount of calcium in their urine and increase their risk of forming stones. Patients with HIV who take the medication indinavir (Crixivan) can form indinavir stones.