Kidney Stones Overview
Kidney stones are one of the most common disorders of the urinary tract, and one of the most painful. In the United States, approximately 1 million people suffer an attack of kidney stones every year.
Stones most typically affect people between the ages of 20 and 40, men more frequently than women. Risk also increases if there is a family history of kidney stones.
About the Kidneys
Kidney stones can develop when crystals form in urine and build up on the inner surface of the kidney. The kidneys are two bean-shaped organs in the lower back. Their main function is to remove waste from the body and to balance the water and mineral content of the blood by removing water. The waste and water are combined to form urine.
The kidneys filter the blood and remove liquid waste from the body in the form of urine. From the kidneys, urine flows down the ureters, two thin tubes that connect the kidneys to the bladder. The bladder stores urine until it is eliminated from the body through a tube called the urethra.
How Do Kidney Stones Form?
Kidney stones can develop when crystals form in the urine and build up on the inner surfaces of the kidney. Most stones are made of calcium and oxalate, a substance found in nuts, leafy greens, chocolate, and vitamin C. The stones may either remain in the kidney or travel down the ureter.
Most stones are so small that they pass through the urinary system unnoticed. However, when a larger stone moves into the ureter, it causes irritation or blockage.
Symptoms of Kidney Stones
Usually, the first symptom of a kidney stone is sudden, sharp, cramping pain in the area of the kidney or lower abdomen. As the stone travels down the ureter closer to the bladder, the need to urinate more often or a burning sensation during urination may occ ur. Blood may appear in the urine. Sometimes nausea and vomiting occur. Later, pain may spread to the groin.
How Are Kidney Stones Diagnosed?
Kidney stones are diagnosed through a combination of the patient's symptoms, evaluation of the urine, blood testing and imaging studies.
The most common imaging studies for diagnosing kidney stones include KUB, Ultrasound and CT.
KUB is a simple abdominal x-ray aimed at assessing the presence of stones in the kidney, ureter and bladder. This study is quick, readily available and involves low exposure to radiation.
Ultrasound uses high frequency sound waves to create images of the urinary system. This study is safe in pregnancy as it does not use radiation.
A CT scan takes cross-sectional pictures of the body. This is the most accurate study for kidney stones and can detect even small stones not showing on an ultrasound or KUB.
You may be asked to urinate through a strainer. If you pass a stone it can be sent for analysis. The stone composition may help your doctor formulate a stone prevention plan.
Next Steps After Diagnosis
Don't change your diet without consulting your doctor. Recommendations will be based on the type of stones you've had, and the results of your 24-hour urine tests. Be sure to ask your doctor for a list of the foods you should avoid, or meet with a dietician who can help you understand your dietary restrictions.
You may be advised to:
Medications may include:
Drugs that control the amount of acid in the urine, such as Allopurinol; sodium cellulose phosphate for urine high in calcium; Hydrochlorothiazide (a diuretic) to reduce the amount of calcium released by the kidneys; or Thiola to reduce the amount of cystine in the urine.
Most kidney stones pass out of the body in the urine without any active medical intervention, but there are a variety of treatment options available when intervention is needed. Most do not involve major surgery. The options are:
The Department of Urology also provides specialty care for kidney stone disease over the long term. The Department is currently conducting exciting research into new and better ways to treat and manage advanced disease. For patient referral or consultations, contact the Department of Urology at 412-692-4100.