What is a kidney stone?
A kidney stone is a hard mass developed from crystals that separate from the urine within the urinary tract. Normally, urine contains chemicals that prevent or inhibit the crystals from forming. These inhibitors do not seem to work for everyone, however, so some people form stones. If the crystals remain tiny enough, they will travel through the urinary tract and pass out of the body in the urine without being noticed.
Kidney stones may contain various combinations of chemicals. The most common type of stone contains calcium in combination with either oxalate or phosphate. These chemicals are part of a person’s normal diet and make up important parts of the body, such as bones and muscles.
A less common type of stone is caused by infection in the urinary tract. This type of stone is called a struvite or infection stone. Another type of stone, uric acid stones, are a bit less common, and cystine stones are rare.Urolithiasis is the medical term used to describe stones occurring in the urinary tract. Other frequently used terms are urinary tract stone disease and nephrolithiasis.
Doctors also use terms that describe the location of the stone in the urinary tract. For example, a ureteral stone—or ureterolithiasis—is a kidney stone found in the ureter. To keep things simple, the general term kidney stones is used throughout this page.
Gallstones and kidney stones are not related. They form in different areas of the body. Someone with a gallstone is not necessarily more likely to develop kidney stones.
What causes kidney stones?
A person with a family history of kidney stones may be more likely to develop stones.
Urinary tract infections, kidney disorders such as cystic kidney diseases, and certain metabolic disorders such as hyperparathyroidism are also linked to stone formation.
In addition, more than 70 percent of people with a rare hereditary disease called renal tubular acidosis develop kidney stones.Cystinuria and hyperoxaluria are two other rare, inherited metabolic disorders that often cause kidney stones. In cystinuria, too much of the amino acid cystine, which does not dissolve in urine, is voided, leading to the formation of stones made of cystine. In patients with hyperoxaluria, the body produces too much oxalate, a salt. When the urine contains more oxalate than can be dissolved, the crystals settle out and form stones.
Hypercalciuria is inherited, and it may be the cause of stones in more than half of patients. Calcium is absorbed from food in excess and is lost into the urine. This high level of calcium in the urine causes crystals of calcium oxalate or calcium phosphate to form in the kidneys or elsewhere in the urinary tract.
Other causes of kidney stones are hyperuricosuria, which is a disorder of uric acid metabolism; gout; excess intake of vitamin D; urinary tract infections; and blockage of the urinary tract. Certain diuretics, commonly called water pills, and calcium-based antacids may increase the risk of forming kidney stones by increasing the amount of calcium in the urine.
Calcium oxalate stones may also form in people who have chronic inflammation of the bowel or who have had an intestinal bypass operation, or ostomy surgery. As mentioned earlier, struvite stones can form in people who have had a urinary tract infection. People who take the protease inhibitor indinavir, a medicine used to treat HIV infection, may also be at increased risk of developing kidney stones.
What are the Risk factors for Kidney Stones?
Several factors make it more likely you will get kidney stones. Some of these you can control, and others you cannot.
Risk factors you can controlRisk factors for both new and recurring kidney stones that you can control include:
- Fluids you drink.
- The most common cause of kidney stones is not drinking enough water. Try to drink enough water to keep your urine clear (about 8 to 10 glasses of water a day).
- Drinking grapefruit juice may increase your risk for developing kidney stones.
- Diet. If you think that your diet may be a problem, schedule an appointment with a dietitian and review your food choices.
- Vitamins C and D can increase your risk of kidney stones when you take more than the daily recommendations. Read supplement labels carefully, and do not take more than the recommended daily doses.
- Levels of calcium affect your risk of kidney stones. Getting your recommended amounts of calcium combined with a low-sodium, low-protein diet may decrease your risk of kidney stones.
- Diets high in protein, sodium, and oxalate-rich foods, such as dark green vegetables, increase your risk for developing kidney stones.
- Weight and weight gain. Weight gain can result in both insulin resistance and increased calcium in the urine, which can result in a greater risk for kidney stones. In one study, weight gain since early adulthood, a high body mass index (BMI), and a large waist size increased a person's risk for kidney stones.
- Activity level. People who are not very active may have more problems with kidney stones.
- Medicine. Some medicines, such as acetazolamide (Diamox), or indinavir (Crixivan), can cause kidney stones to form.
Risk factors you cannot controlRisk factors for both new and recurring kidney stones that you cannot control include:
- Age and gender.
- Men between the ages of 30 and 50 are most likely to get kidney stones.
- Postmenopausal women with low estrogen levels have an increased risk for developing kidney stones. Women who have had their ovaries removed are also at increased risk.
- A family history of kidney stones.
- A personal history of frequent urinary tract infections.
- Other diseases or conditions, such as inflammatory bowel disease, hyperparathyroidism, cystic fibrosis, gout, or high blood pressure.
- Insulin resistance, which can occur because of diabetes or obesity.
- Prolonged bed rest.
- Bladder problems caused by spinal cord injury.
- Medicines used to control other conditions or diseases, such as antacids or aspirin.
- An abnormal urinary tract, such as the kidneys being joined (horseshoe kidneys
What are the Symptoms and Signs of Kidney Stones?
When a tubular structure is blocked in the body, waves of pain occur as the body tries to unblock the obstruction. These waves of pain are called colic. This is opposed to non-colicky type pain, like that associated with appendicitis or pancreatitis, in which movement causes increased pain and the patient tries to hold very still.
- Renal colic (renal is the medical term for things related to the kidney) has a classic presentation when a kidney stone is being passed.
- The pain is intense and comes on suddenly. It may wax and wane, but there is usually a significant underlying ache between the acute spasms of pain.
- It is usually located in the flank or the side of the mid back and may radiate to the groin. Males may complain of pain in the testicle or scrotum.
- The patient cannot find a comfortable position and often writhes or paces with pain.
- Sweating, nausea, and vomiting are common.
- Blood may or may not be visible in the urine because the stone has irritated the kidney or ureter. Blood in the urine (hematuria), however, does not always mean a person has a kidney stone. There may be other reasons for the blood, including kidney and bladder infections, trauma, or tumors. Urinalysis with a microscope may detect blood even if it is not appreciated by the naked eye. Sometimes, if the stone causes complete obstruction, no blood may be found in the urine because it cannot get past the stone.
In order to diagnose a patient with kidney stones, doctors will typically:
- Gather a complete medical history
- Ask about the patient's occupation
- Ask about the patient's eating habits
- Order laboratory tests, which include urine and blood tests.
The laboratory should also analyze any stones that are removed from a patient because the composition of the stones may help with kidney stones treatment.
Doctors use several tests or procedures when making a kidney stones diagnosis, including:
- Ultrasound (sonogram)
- CT (computed tomography) scan
- Intravenous pyelogram (IVP).
X-Rays or Ultrasound
Sometimes, "silent" stones -- those that do not cause symptoms -- are found on x-rays that are taken during a general health exam. However, in most cases, kidney stones are found on an x-ray or sonogram that is taken on someone who complains of specific symptoms, such as blood in the urine or sudden pain. These diagnostic images can give the doctor valuable information about the stone's size and location. Blood and urine tests may also help detect any abnormal substance that might promote stone formation.
CT Scan or IVP
The doctor may decide to scan the urinary system using a special test called a CT (computed tomography) scan or an IVP (intravenous pyelogram). The results of these tests can help determine the proper treatment for kidney stones.
Patients may be asked to collect their urine for 24 hours after a stone has passed or been removed. The sample will be used to measure:
- Urine volume
- Levels of acidity
- Levels of calcium
- Levels of sodium
- Levels of uric acid
- Levels of oxalate
- Levels of citrate
- Levels of creatinine (a product of muscle metabolism).
Your doctor will use this information to determine the cause of your kidney stones, and a second 24-hour urine collection may be needed to determine whether the prescribed treatment is working
How are kidney stones treated?
Fortunately, surgery is not usually necessary. Most kidney stones can pass through the urinary system with plenty of water—2 to 3 quarts a day—to help move the stone along. Often, the patient can stay home during this process, drinking fluids and taking pain medication as needed. The doctor usually asks the patient to save the passed stone(s) for testing. It can be caught in a cup or tea strainer used only for this purpose.
A simple and most important lifestyle change to prevent stones is to drink more liquids—water is best. Someone who tends to form stones should try to drink enough liquids throughout the day to produce at least 2 quarts of urine in every 24-hour period.
In the past, people who form calcium stones were told to avoid dairy products and other foods with high calcium content. Recent studies have shown that foods high in calcium, including dairy products, may help prevent calcium stones. Taking calcium in pill form, however, may increase the risk of developing stones.
Patients may be told to avoid food with added vitamin D and certain types of antacids that have a calcium base. Someone who has highly acidic urine may need to eat less meat, fish, and poultry. These foods increase the amount of acid in the urine.
To prevent cystine stones, a person should drink enough water each day to dilute the concentration of cystine that escapes into the urine, which may be difficult. More than a gallon of water may be needed every 24 hours, and a third of that must be drunk during the night.
A doctor may prescribe certain medications to help prevent calcium and uric acid stones. These medicines control the amount of acid or alkali in the urine, key factors in crystal formation. The medicine allopurinol may also be useful in some cases of hyperuricosuria.
Doctors usually try to control hypercalciuria, and thus prevent calcium stones, by prescribing certain diuretics, such as hydrochlorothiazide. These medicines decrease the amount of calcium released by the kidneys into the urine by favoring calcium retention in bone. They work best when sodium intake is low.
Rarely, patients with hypercalciuria are given the medicine sodium cellulose phosphate, which binds calcium in the intestines and prevents it from leaking into the urine.
If cystine stones cannot be controlled by drinking more fluids, a doctor may prescribe medicines such as Thiola and Cuprimine, which help reduce the amount of cystine in the urine.
For struvite stones that have been totally removed, the first line of prevention is to keep the urine free of bacteria that can cause infection. A patient’s urine will be tested regularly to ensure no bacteria are present.
If struvite stones cannot be removed, a doctor may prescribe a medicine called acetohydroxamic acid (AHA). AHA is used with long-term antibiotic medicines to prevent the infection that leads to stone growth.
People with hyperparathyroidism sometimes develop calcium stones. Treatment in these cases is usually surgery to remove the parathyroid glands, which are located in the neck. In most cases, only one of the glands is enlarged. Removing the glands cures the patient’s problem with hyperparathyroidism and kidney stones.
Surgery may be needed to remove a kidney stone if it
- does not pass after a reasonable period of time and causes constant pain
- is too large to pass on its own or is caught in a difficult place
- blocks the flow of urine
- causes an ongoing urinary tract infection
- damages kidney tissue or causes constant bleeding
- has grown larger, as seen on follow-up x rays
Extracorporeal Shock Wave Lithotripsy
Extracorporeal shock wave lithotripsy (ESWL) is the most frequently used procedure for the treatment of kidney stones. In ESWL, shock waves that are created outside the body travel through the skin and body tissues until they hit the denser stones. The stones break down into small particles and are easily passed through the urinary tract in the urine.
Several types of ESWL devices exist. Most devices use either x rays or ultrasound to help the surgeon pinpoint the stone during treatment. For most types of ESWL procedures, anesthesia is needed.
In many cases, ESWL may be done on an outpatient basis. Recovery time is relatively short, and most people can resume normal activities in a few days.
Complications may occur with ESWL. Some patients have blood in their urine for a few days after treatment. Bruising and minor discomfort in the back or abdomen from the shock waves can occur. To reduce the risk of complications, doctors usually tell patients to avoid taking aspirin and other medicines that affect blood clotting for several weeks before treatment.
Sometimes, the shattered stone particles cause minor blockage as they pass through the urinary tract and cause discomfort. In some cases, the doctor will insert a small tube called a stent through the bladder into the ureter to help the fragments pass. Sometimes the stone is not completely shattered with one treatment, and additional treatments may be needed.
As with any interventional, surgical procedure, potential risks and complications should be discussed with the doctor before making a treatment decision.
Sometimes a procedure called percutaneous nephrolithotomy is recommended to remove a stone. This treatment is often used when the stone is quite large or in a location that does not allow effective use of ESWL.
In this procedure, the surgeon makes a tiny incision in the back and creates a tunnel directly into the kidney. Using an instrument called a nephroscope, the surgeon locates and removes the stone. For large stones, some type of energy probe—ultrasonic or electrohydraulic—may be needed to break the stone into small pieces. Often, patients stay in the hospital for several days and may have a small tube called a nephrostomy tube left in the kidney during the healing process.
One advantage of percutaneous nephrolithotomy is that the surgeon can remove some of the stone fragments directly instead of relying solely on their natural passage from the kidney.
Ureteroscopic Stone Removal
Although some stones in the ureters can be treated with ESWL, ureteroscopy may be needed for mid- and lower-ureter stones. No incision is made in this procedure. Instead, the surgeon passes a small fiberoptic instrument called a ureteroscope through the urethra and bladder into the ureter. The surgeon then locates the stone and either removes it with a cage-like device or shatters it with a special instrument that produces a form of shock wave. A small tube or stent may be left in the ureter for a few days to help urine flow. Before fiber optics made ureteroscopy possible, physicians used a similar “blind basket” extraction method. But this technique is rarely used now because of the higher risks of damage to the ureters.
Home Remedy for kidney stones
Stones lesser than 4mm in size usually pass out spontaneously, without any complications. Follow these guidelines if the stones are relatively small and can pass out while urinating.
- Dried French beans or Rajmah is an effective ingredient to get rid of all kidney problems including Kidney stones. Remove the beans from the pods, and slice the pods in small sizes and boil it in 4 liter of hot water in low flame for six hours continuously. Strain the liquid twice through fine muslin and cool it for eight hours. A glass of this fluid should be given to the patient every two hours throughout the day. The patient may consume it several times a week. Make sure you don't prepare the decoction in plenty, as it will not work if it is more than 24 hours old.
- Take one teaspoon each of basil juice and honey daily for six months.
- Intake of vitamin B6 or pyridoxine is the best treatment for kidney stones. A daily therapeutic dose of 100 to 150 mg of Vitamin B6 combined with other B complex vitamins helps in getting a permanent cure.
- Take a tablespoon of pomegranate seed and grind it into a fine paste and give it to the patient with a cup of horse gram soup. A cup of horse gram soup should be prepared by using two tablespoon of it.
- Drink a lot of water that you will be able to pass 2 quarts of urine a day.
- Nettle helps to keep crystals from forming into stone. It even helps to wash away the bacteria. Drink 2-3 cups of nettle leaf per day to prevent kidney stones. Mix 1-2 tablespoon of dried nettle leaf with 1cup of hot water and steep for 10-15 minutes.
How do we prevent Kidney Stones?
If you have more than one kidney stone, especially if you have a family history of stones, you are more likely to have kidney stones again. But you can take steps to help prevent them:
- Drink more fluids. Try to drink enough water to keep your urine clear, about 8 to 10 glasses of water per day. Slowly increase how much you drink, perhaps adding one more glass of water a day until you are drinking 8 to 10 glasses a day. This slow increase will give your body time to adjust to the extra fluids. You are drinking enough water when your urine is clear or light yellow. If it is dark yellow, you are not drinking enough fluids. If you have kidney, heart, or liver disease and have fluid restrictions, talk with your doctor before increasing how much you drink.
- Change your diet. This may be helpful, but it depends on what is causing your kidney stones. Your doctor may do more tests before deciding whether changing your diet will help reduce your risk for developing another stone. The results of these tests may suggest that it could be helpful to do one or more of the following:
- Increase how much fiber you eat. Fiber includes oat bran, beans, whole wheat breads, wheat cereals, cabbage, and carrots.
- Eat less beef, pork, and poultry.
- Eat a moderate or high amount of calcium-rich foods, such as dairy products. Getting your recommended amounts of calcium, combined with a diet low in sodium and protein, may decrease your risk of kidney stones.
- Try not to drink grapefruit juice. Drinking grapefruit juice may increase your risk for developing kidney stones.
- Avoid foods that are high in oxalate listed below.
- Try not to add salt when you cook or eat. Try removing the salt shaker from your table.
Foods and Drinks Containing Oxalate
People prone to forming calcium oxalate stones may be asked by their doctor to limit or avoid certain foods if their urine contains an excess of oxalate.
High-oxalate foods—higher to lower
- swiss chard
- wheat germ
- soybean crackers
- black Indian tea
- sweet potatoes
Foods that have medium amounts of oxalate may be eaten in limited amounts.
Medium-oxalate foods—higher to lower
- green pepper
- red raspberries
- fruit cake
Call a doctor immediately if you have symptoms that suggest you have a kidney stone, such as:
If you are passing a kidney stone under your doctor's advice, you may be able to pass the stone without medical treatment if you:
- Severe pain in your side, abdomen, groin, or genitals. It may get worse in waves.
- Blood in your urine.
- Signs of a urinary tract infection.
- Severe nausea or vomiting.
- Fever and chills.
- Severe pain in your side in the area of your kidney (flank pain).
- Have been diagnosed with a kidney stone, and you need a stronger pain medicine.
- Pass a stone, even if there was little or no pain. Save the stone, and ask your doctor whether it should be tested.
Watchful WaitingWatchful waiting is a wait-and-see approach. If you get better on your own, you won't need medical treatment. If you get worse, you and your doctor will decide what to do next.
If you are passing a kidney stone under your doctor's advice, you may be able to pass the stone without medical treatment if you:
- Can control your pain with medicine.
- Know how to look for and collect kidney stones you pass.
- Do not have signs of infection, such as fever and chills.
- Are able to drink plenty of fluids.
- Do not have severe nausea or vomiting.
Points to Remember
- A person with a family history of stones or a personal history of more than one stone may be more likely to develop more stones.
- A good first step to prevent the formation of any type of stone is to drink plenty of liquids—water is best.
- Someone who is at risk for developing stones may need certain blood and urine tests to determine which factors can best be altered to reduce that risk.
- Some people will need medicines to prevent stones from forming.
- People with chronic urinary tract infections and stones will often need a stone removed if the doctor determines that the stone is causing the infection. Patients must receive careful follow-up to be sure that the infection has cleared.