Kidney stones are hard deposits of minerals and salts that form inside your kidneys. The causes of kidney stones vary and can affect any part of your urinary tract. Most of the time, stones form when urine becomes concentrated, allowing minerals to crystallize and stick together.
Each year, more than 1 million people in the U.S. rush to the emergency room with pain caused by a kidney stone. They affect one in 11 people in the United States. Overall, about 19 % of men and 9% of women in the United States will develop a kidney stone by the time they are 70 years old. Of those who develop one stone, half will develop at least one more in the future.
Passing a stone is the process of the stone moving out of the kidney and through ureter (the tube that carries urine to the bladder). It can be very painful, but the stones usually do not cause permanent damage if they are recognized early.
There are usually no symptoms until the stone begins to pass into the ureter. When symptoms appear, they commonly include:
- Severe pain in the side and back, below the ribs
- Pain that radiates to the lower abdomen and groin
- Pain that comes in waves and fluctuates in intensity
- Pain during urination
- Pink, red, or brown urine (blood in the urine)
- Cloudy or foul-smelling urine
- Vomiting and nausea
- White blood cells or pus in the urine
- Reduced amount of urine excreted
- Burning sensation during urination
- Persistent urge to urinate
- Fever and chills – if there is an infection
Kidney stones are more common among males than females. Most people who experience kidney stones are between the ages of 30 and 50. A family history of kidney stones can also increase a person’s chances of developing them, as does a personal history of having kidney stones if preventative actions were not taken.
Certain medications can also increase a person’s chances of developing kidney stones. Topiramate (Topamax), a drug commonly prescribed to treat migraine headaches and seizures, can increase the likelihood of developing kidney stones. Long-term use of vitamin D and calcium supplements cause high calcium levels, which can contribute to kidney stones.
Medical conditions such as Crohn’s disease, diabetes, urinary tract infections, renal tubular acidosis, hyperparathyroidism, medullary sponge kidney, and Dent’s disease increase the risk of developing kidney stones.
Additional risks factors for kidney stones include diets high in protein and sodium but low in calcium, a sedentary lifestyle, obesity, high blood pressure, and conditions that affect how calcium is absorbed in the body such as gastric bypass surgery, inflammatory bowel disease, and chronic diarrhea.
Dietary habits that may contribute to the formation of kidney stones include:
- Not drinking enough water
- Not getting enough calcium
- A diet high in sugar and salt
- Eating large amounts of oxalate-rich foods (such as nuts, spinach, chocolate, and certain teas)
- Drinking soda, which contains phosphate and have a high sugar content
- Consuming too much protein
- A lack of citrate, a substance that helps prevent stones from forming
The leading cause of kidney stone is a lack of water in the body. Stones are more commonly found in people who drink less water than the recommended 8 – 10 glasses a day. When there is not enough water to dilute the uric acid (a component of urine), the urine becomes acidic. An excessively acidic environment in urine can lead to the formation of kidney stone.
There are two main types of kidney stones: calcium stones and non-calcium stones. High levels of calcium in the urine account for about 80% of all kidney stones. Calcium can bind with other substances – like oxalate and phosphate – in the urine to form stones. Non-calcium stones include:
- Uric Acid Stones – These form when the urine contains too much acid.
- Cystine Stones – These develop when the urine contains too much of the amino acid cystine.
- Struvite Stones – These form from the waste products of bacteria associated with infection and are composed of magnesium ammonium phosphate.
For people in good health, preventing kidney stones can be as easy as staying hydrated.
You may reduce your risk with lifestyle changes. These include:
- Drink more water throughout the day
- Eat fewer oxalate-rich foods – If you tend to form calcium oxalate stones, your doctor may recommend you restrict foods rich in oxalate. These include rhubarb, beets, okra, spinach, Swiss chard, sweet potatoes, nuts, teas, chocolate, black pepper, and soy products.
- Choose a diet low in salt and animal protein
- Continue eating calcium-rich foods, but use caution with calcium supplements.
Doctors may prescribe medicine to prevent certain types of stones for people at a higher risk.
For calcium stones – your doctor may prescibe a thiazide diuretic or a phosphate-containing preparation
- For uric acid stones – Your doctor may prescribe allopurinol (Zyloprim, Aloprimn) to reduce uric acid levels in your blood and urine and a medicine to keep your urine alkaline. In some cases, allopurinol and an alkalizing agent my dissolve the uric acid stones.
- For struvite stones – you doctor may recommend strategies to keep your urine free of bacteria that cause infections. Long-term use of antibiotics in small doses may help achieve this goal.
- For cystine stones – These can be difficult to treat. Your doctor may recommend more water to help you produce more urine. Your doctor my also prescribe a medication that decrease the amount of cystine in your urine.
Make an appointment with your doctor if you have any signs and symptoms that worry you.
Seek immediate medical attention if you experience:
- Pain so severe that you can’t sit still or find a comfortable position
- Pain accompanied by nausea and vomiting
- Pain accompanied by fever and chills
- Blood in your urine
- Difficulty passing urine
Small Stones with Minimal Symptoms
Most small stones will not require invasive treatment. You may be able to pass the stone by:
- Drinking water – Drinking 2-3 quarts of water a day may help flush out the stone. Unless your doctor tell you otherwise, drink enough water to produce clear or nearly clear urine.
- Pain relievers – Passing a stone can cause discomfort. To relieve mild pain, your doctor may recommend pain relievers such as ibuprofen, acetaminophen, or naproxen sodium.
- Medical therapy – Your doctor may give you medication to help pass your kidney stone. This type of medicine is a beta blocker and relaxes the muscles in your ureter, helping you pass the kidney stone more quickly and with less pain.
Large stones and those that cause symptoms
Kidney stones that are too large to pass on their own or because they cause bleeding, kidney damage, or ongoing urinary tract infections – may require more-extensive treatment. Procedures may include:
- Using sound waves to break up stones – Depending on the size and location, your doctor may recommend a procedure called extracorporeal shock wave lithotripsy (ESWL). This uses sound waves to create a strong vibration to break the stone into tiny pieces that can be passed in your urine. The procedure last about 45-60 minutes and can cause moderate pain. You may be under sedation or light anesthesia to may you comfortable. ESWL can cause blood in the urine, bruising on the back of the abdomen, bleeding around the kidney and other adjacent organs and discomfort as the stone fragments pass through the urinary tract.
- Surgery to remove very large stones in the kidney – A procedure called percutaneous nephrolithotomy involves surgically removing a kidney stone using small telescope and instruments inserted through a small incision in your back. You will receive general anesthesia during the surgery and be in the hospital for one to two days while you recover. Your doctor may recommend this surgery if ESWL was unsuccessful.
- Using a scope to remove stones – To remove smaller stones in your ureter or kidney, your doctor may pass a thin lighted tube (ureteroscope) equipped with a camera through your urethra and bladder to your ureter. Once the stone is located, special tools can snare the stone or break it into pieces that will pass in your urine. Your doctor may then place a small tube (stent) in the ureter to relieve swelling and promote healing. You may need general or local anesthesia during this procedure.
- Parathyroid glad surgery – Some calcium phosphate stones are caused by overactive parathyroid glands. When these glands produce too much parathyroid hormone (hyperparathyroidism), your calcium levels can become too high and kidney stone may form as a result. Hyperparathyroidism can happen when a small, benign tumor forms in one of the parathyroid glands. Removing this growth from the gland stops the formation of kidney stones.
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