About one person out of every 1,000 adults goes into the hospital in the United States because of kidney stones. These can be too tiny to see with the eye alone to more than an inch across.
Kidney stones can be made up of:
- Calcium, which accounts for nearly four out of every five kidney stones
- Uric acid, which is when there is more acidic acid in the urine
- Cystine, which are formed by cystinuria
- Magnesium ammonium phosphate, also called struvite. This is a sign of bacteria It must be treated as an infection. This type occurs mostly in women.
Many kidney stones cause no symptoms at all. When kidney stones do cause symptoms they usually include:
- Pain. A person may feel pain across the back or pain that starts in the back or kidney area. The pain goes along the line of the vessel that carries urine from the kidneys to the outside of the body. A person may also feel pain in the genital region and inner thigh. This pain is typically very severe and comes and goes. Stones in the bladder may cause pain in the pubic region.
- A block in the urinary system
- Nausea, vomiting, a bloated stomach may disguise what is actually kidney stones
- Chills, fever, hematuria and a need to go to the bathroom often may also be experienced. This happens especially if the stones are moving down the ureter.
- The affected kidney may stop working for a while because of a stone, even after it has passed out the body by itself.
Causes and Risk Factors
Kidney stones develop when the urine is supersaturated with salts that can form into stones. This includes overexcretion of salt, having acid urine or having a low volume of urine.
A tendency to develop kidney stones tends to run in some families. It is the primary risk factor for developing kidney stones of calcium.
Kidney stones can develop as a result of:
- Hyperoxaluria, which can be caused by eating too many foods that contain oxalate. This includes rhubarb, spinach, cocoa, nuts, pepper or tea. Absorbing too much oxalate into the body as a result of various enteric diseases including chronic pancreatic or biliary disease or ileojejunal surgery can also cause it.
- Hyperuricosuria, which is almost always a result of eating too much purine. Purine is is found in meat, fish and poultry.
In rare cases, the kidney stones may be a result of hyperparathyroidism, hyperthyroidism, multiple Myeloma, sarcoidosis, vitamin D intoxication, cancer that has spread or hyperoxaluria.
To diagnose kidney stones, a doctor will usually:
- Examine the person and get a medical history
- Rule out conditions such as appendicitis, cholecystitis, ulcers, pancreatitis, ectopic pregnancy or a dissecting aneurysm
- Review the food the patient has been eating to check for risk factors such as a high protein diet or a habit of taking vitamin C or D supplements
- Do a blood test to check the calcium levels in the blood
- Check for signs of any kidney abnormality
- Do a urinalysis
- Do an X-ray, which will show the presence of most kidney stones. However, some types of stones can't be seen on an X-ray.
- Check for Pyramidal Ca deposits, which can also indicate a number of health conditions. Ultrasound may also be helpful.
- Retrograde urography or IVU may show blockages.
- Computed tomography (CT) scans are useful in the emergency room evaluation of severe pain to help detect a calculus, the degree of blockage, or another cause of the pain (e.g., aortic aneurysm, appendicitis).
Once a person has had one kidney stone, he or she is at greater risk of forming others in the future. Specific treatments will depend on the person's medical history and measurement of the stone-producing substances in the urine.
Options for reducing the likelihood of kidney stones may include:
- Increasing the amount of fluids the person takes
- Taking diuretic drugs to speed up the excretion of urine
- Depending on the cause of the stones, the person's diet may be changed to eliminate foods that can cause kidney stones to develop.
- Drugs may be prescribed to reduce the risk
Treating existing kidney stones varies from taking no action to minimally invasive procedures to surgery. No action may be needed if the stones are small, there's no infection and the urinary system has no blockages.
Treatment options include:
- Treating an infection if that is the cause of the stones
- Shock wave lithotripsy (SWL) for stones that are less than two centimeters across
- Minimally invasive surgery to remove larger stones in the kidneys or ureter
- Intracorporeal lithotripsy to break up the stones
- Prescription drugs to dissolve uric acid stones