Kidney stones

Answer 1

Definition

A kidney stone is a solid mass made up of tiny crystals. One or more stones can be in the kidney or ureter at the same time.

See also: Cystinuria

Alternative Names

Renal calculi; Nephrolithiasis; Stones - kidney

Causes, incidence, and risk factors

Kidney stones can form when urine contains too much of certain substances. These substances can create small crystals that become stones.

The biggest risk factor for kidney stones is dehydration.

Kidney stones may not produce symptoms until they begin to move down the tubes (ureters) through which urine empties into the bladder. When this happens, the stones can block the flow of urine out of the kidneys. This causes swelling of the kidney or kidneys, causing pain. The pain is usually severe.

Kidney stones are common. A person who has had kidney stones often gets them again in the future. Kidney stones often occur in premature infants.

Some types of stones tend to run in families. Certain kinds of stones can occur with bowel disease, ileal bypass for obesity, or renal tubule defects.

There are different types of kidney stones. The exact cause depends on the type of stone.

• Calcium stones are most common. They occur more often in men than in women, and usually appear between ages 20 - 30. They are likely to come back. Calcium can combine with other substances, such as oxalate (the most common substance), phosphate, or carbonate to form the stone. Oxalate is present in certain foods. Diseases of the small intestine increase the risk of forming calcium oxalate stones.
• Cystine stonescan form in people who have cystinuria. This disorder runs in families and affects both men and women.
• Struvite stones are mostly found in women who have a urinary tract infection. These stones can grow very large and can block the kidney, ureter, or bladder.
• Uric acidstones are more common in men than in women. They can occur with gout or chemotherapy.

Other substances also can form stones.

Symptoms

The main symptom is severe pain that starts suddenly and may go away suddenly:

• Pain may be felt in the belly area or side of the back
• Pain may move to groin area (groin pain) or testicles (testicle pain)

Other symptoms can include:

• Abnormal urine color
• Blood in the urine
• Chills
• Fever
• Nausea
• Vomiting

Signs and tests

Pain can be severe enough to need narcotic pain relievers. The belly area (abdomen) or back might feel tender to the touch.

Tests for kidney stones include:

• Analysis of the stone to show what type of stone it is
• Uric acidlevel
• Urinalysis to see crystals and red blood cells in urine

Stones or a blockage of the ureter can be seen on:

• Abdominal CT scan
• Abdominal/kidney MRI
• Abdominal x-rays
• Intravenous pyelogram (IVP)
• Kidney ultrasound
• Retrograde pyelogram

Tests may show high levels of calcium, oxylate, or uric acid in the urine or blood.

Treatment

The goal of treatment is to relieve symptoms and prevent further symptoms. (Kidney stones that are small enough usually pass on their own.) Treatment varies depending on the type of stone and how severe the symptoms are. People with severe symptoms might need to be hospitalized.

When the stone passes, the urine should be strained and the stone saved and tested to determine the type.

Drink at least 6 - 8 glasses of water per day to produce a large amount of urine. Some people might need to get fluids through a vein (intravenous).

Pain relievers can help control the pain of passing the stones (renal colic). For severe pain, you may need to take narcotic pain killers or nonsteroidal anti-inflammatory drugs (NSAIDS) such as ibuprofen.

Depending on the type of stone, your doctor may prescribe medicine to decrease stone formation or help break down and remove the material that is causing the stone. Medications can include:

• Allopurinol (for uric acid stones)
• Antibiotics (for struvite stones)
• Diuretics
• Phosphate solutions
• Sodium bicarbonate or sodium citrate (which make the urine more alkaline)

Surgery is usually needed if:

• The stone is too large to pass on its own
• The stone is growing
• The stone is blocking urine flow and causing an infection or kidney damage

Today, most treatments are much less invasive than in the past.

• Extracorporeal shock-wave lithotripsy is used to remove stones slightly smaller than a half an inch that are located near the kidney. This method uses ultrasonic waves or shock waves to break up stones. Then, the stones leave the body in the urine.
• Percutaneous nephrolithotomy is used for large stones in or near the kidney, or when the kidneys or surrounding areas are incorrectly formed. The stone is removed with an endoscope that is inserted into the kidney through a small opening.
• Ureteroscopy may be used for stones in the lower urinary tract.
• Standard open surgery (nephrolithotomy) may be needed if other methods do not work or are not possible.

Expectations (prognosis)

Kidney stones are painful but usually can be removed from the body without causing permanent damage. They tend to return, especially if the cause is not found and treated.

Complications

• Decrease or loss of function in the affected kidney
• Kidney damage, scarring
• Obstruction of the ureter (acute unilateral obstructive uropathy)
• Recurrence of stones
• Urinary tract infection

Calling your health care provider

Call your health care provider if you have symptoms of a kidney stone.

Also call if symptoms return, urination becomes painful, urine output decreases, or other new symptoms develop.

Prevention

If you have a history of stones, drink plenty of fluids (6 - 8 glasses of water per day) to produce enough urine. Depending on the type of stone, you might need to take medications or other measures to prevent the stones from returning.

You may need to change your diet to prevent some types of stones from coming back.

References

Cameron MA, Sakhaee K. Uric acid nephrolithiasis. Urol Clin North Am. 2007;34(3):335-346.

Chandhoke PS. Evaluation of the recurrent stone former. Urol Clin North Am. 2007; 34(3):315-322.

Finkielstein VA. Strategies for preventing calcium oxalate stones. CMAJ. 2006;174(10):1407-1409.

Pietrow PK, Preminger GM. Evaluation and medical management of urinary lithiasis. In: Wein AJ, ed. Campbell-Walsh Urology. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 43.

Answer 2

Kidney stones are comparable to the pain that a woman would experience when she is in labor. It is a pain that is unforgettable and if you feel it, you need to get to a doctor immediately. If kidney stones are left untreated, they can cause infections in the kidneys or bladder.

One of the first symptoms of kidney stones is an intense pain in either side of the abdomen. This pain can also be located in the back. Pain in the abdomen is also associated with gallstones and kidney infections, so if you begin to hurt, you should see a doctor to find out what the pain is coming from. Sometimes the pain from kidney stones is great enough to make you feel nauseous. You may also have some bleeding when you urinate. This is one of the initial symptoms that the kidney stone is lodged in the tubes from the kidneys and your body is trying to eliminate it.

When you see the doctor they will ask you how intense your pain is. If you are in a lot of pain, they may administer morphine or another pain reliever. An x-ray will be done to determine if you do have kidney stones, and if you do, they can see where they are located. Smaller stones can be passed when you urinate and don't require any further action to get rid of them. Drinking plenty of water and cranberry juice can increase your fluid output, allowing you to pass the stones easier. In the event that there are multiple kidney stones, there are options for you. A procedure called lithotripsy can be done to make the stones smaller. A laser is used to break the stones in the kidneys so they are small enough to pass. Large stones that block the tubes leading from the kidney may need to be surgically removed. If you have had kidney stones at one point in your life, the chances of you having more increase.

Answer 3

The urinary tract includes the kidneys, ureters, bladder and urethra. Within each kidney, urine flows from the outer cortex to the inner medulla. The renal pelvis is the funnel through which urine exits the kidney and enters the ureter.

As urine can become very concentrated as it passes through the kidneys. When the urine becomes too concentrated, calcium, uric acid salts and other chemicals dissolved in the urine can crystallize, forming a kidney stone (renal calculus).

Usually the calculus is the size of a small pebble. But ureters are very sensitive to being stretched, and when stones form and distend it, the stretching can be very painful. Often, people may not know they have kidney stones until they feel the painful symptoms resulting from a stone being stuck anywhere along the urinary tract. Fortunately, small stones typically pass out of the kidneys and through the ureters on their own without causing any problems.

However, stones can become more problematic when they block the flow of urine. A staghorn kidney stone may obstruct the entire kidney. Fortunately, these stones are the exception rather than the rule.

Reviewed By

Review Date: 09/16/2011

David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Scott Miller, MD, Urologist in private practice in Atlanta, Georgia. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Answer 4

Definition

A kidney stone is a solid mass made up of tiny crystals. One or more stones can be in the kidney or ureter at the same time.

See also: Cystinuria

Alternative Names

Renal calculi; Nephrolithiasis; Stones - kidney

Causes, incidence, and risk factors

Kidney stones are common. Some types run in families. They often occur in premature infants.

There are different types of kidney stones. The exact cause depends on the type of stone.

Stones can form when urine contains too much of certain substances. These substances can create small crystals that become stones. The stones take weeks or months to form.

• Calcium stones are most common. They are more common in men between age 20-30. Calcium can combine with other substances, such as oxalate (the most common substance), phosphate, or carbonate to form the stone. Oxalate is present in certain foods such as spinach. It's also found in vitamin C supplements. Diseases of the small intestine increase your risk of these stones.
• Cystine stones can form in people who have cystinuria. This disorder runs in families and affects both men and women.
• Struvite stones are mostly found in women who have a urinary tract infection. These stones can grow very large and can block the kidney, ureter, or bladder.
• Uric acid stones are more common in men than in women. They can occur with gout or chemotherapy.
• Other substances also can form stones including the medications acyclovir, indinavir, and triamterene.

The biggest risk factor for kidney stones is not drinking enough fluids. Kidney stones are more likely to occur if you make less than 1 liter of urine a day. That's slightly more than a quart.

.

Symptoms

You may not have symptoms until the stones move down the tubes (ureters) through which urine empties into your bladder. When this happens, the stones can block the flow of urine out of the kidneys.

The main symptom is severe pain that starts suddenly and may go away suddenly:

• Pain may be felt in the belly area or side of the back
• Pain may move to groin area (groin pain) or testicles (testicle pain)

Other symptoms can include:

• Abnormal urine color
• Blood in the urine
• Chills
• Fever
• Nausea
• Vomiting

Signs and tests

The health care provider will perform a physical exam. The belly area (abdomen) or back might feel sore.

Tests that may be done include:

• Blood tests to check calcium, phosphorus, uric acid, and electrolyte levels
• Kidney function tests
• Urinalysis to see crystals and look for red blood cells in urine
• Examination of the stone to determine the type

Stones or a blockage can be seen on:

• Abdominal CT scan
• Abdominal/kidney MRI
• Abdominal x-rays
• Intravenous pyelogram (IVP)
• Kidney ultrasound
• Retrograde pyelogram

Treatment

Treatment depends on the type of stone and the severity of your symptoms.

Kidney stones that are small usually pass on their own. When the stone passes, the urine should be strained so the stone can be saved and tested.

Drink at least 6 - 8 glasses of water per day to produce a large amount of urine. See also: Kidney stones - self-care

Pain can be severe enough to need narcotic pain relievers. Some people with severe pain from kidney stones need to stay in the hospital. You may need to get fluids through a vein (intravenous).

Depending on the type of stone, your doctor may prescribe medicine to decrease stone formation or help break down and remove the material that is causing the stone. Medications can include:

• Allopurinol (for uric acid stones)
• Antibiotics (for struvite stones)
• Diuretics
• Phosphate solutions
• Sodium bicarbonate or sodium citrate
• Water pills (thiazide diuretics)

Surgery is usually needed if:

• The stone is too large to pass on its own
• The stone is growing
• The stone is blocking urine flow and causing an infection or kidney damage
• The pain cannot be controlled

Today, most treatments are much less invasive than in the past.

• Extracorporeal shock-wave lithotripsy is used to remove stones slightly smaller than a half an inch that are located near the kidney or ureter. It uses sound or shock waves to break up stones. Then, the stones leave the body in the urine.
• Percutaneous nephrolithotomy is used for large stones in or near the kidney, or when the kidneys or surrounding areas are incorrectly formed. The stone is removed with tube (endoscope) that is inserted into the kidney through a small surgical cut.
• Ureteroscopy may be used for stones in the lower urinary tract.
• Rarely, open surgery (nephrolithotomy) may be needed if other methods do not work or are not possible.

See also: Kidney stones - what to ask your doctor

Expectations (prognosis)

Kidney stones are painful but usually can be removed from the body without causing permanent damage.

Kidney stones often come back, especially if the cause is not found and treated.

If treatment is significantly delayed, damage to the kidney or other serious complications can occur.

Complications

• Decrease or loss of function in the affected kidney
• Kidney damage, scarring
• Obstruction of the ureter (acute unilateral obstructive uropathy)
• Recurrence of stones
• Urinary tract infection

Calling your health care provider

Call your health care provider if you have symptoms of a kidney stone.

Also call if symptoms return, urination becomes painful, urine output decreases, or other new symptoms develop.

Prevention

If you have a history of stones, drink plenty of fluids (6 - 8 glasses of water per day) to produce enough urine. Depending on the type of stone, you might need to medications or diet changes to prevent the stones from coming back.

References

Curhan GC. Nephrolithiasis. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 128.

Finkielstein VA. Strategies for preventing calcium oxalate stones. CMAJ. 2006;174(10):1407-1409.

Pietrow PK, Preminger GM. Evaluation and medical management of urinary lithiasis. In: Wein AJ, ed. Campbell-Walsh Urology. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 43.

Reviewed By

Review Date: 09/16/2011

David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Scott Miller, MD, Urologist in private practice in Atlanta, Georgia. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.