Patients who have had kidney stones often ask if they need to change their diet in order to prevent future
recurrence. If you are diagnosed with a kidney stone for the first time, you
have a 60% lifetime chance of forming another stone. While most stones pass
spontaneously, some require surgical intervention. However, non-surgical methods
are necessary to reduce the risk of future recurrence.
Sometimes doctors do
special blood and urine tests to find out the underlying cause of stone
formation. Based on these tests, your doctor may prescribe medications or make
dietary recommendations. 30% of the time no definite cause can be identified.
Long-term medical therapy has potential side effects often forcing patients to
stop the medicines. Random dietary changes based on advice given by friends or
relatives may be counter-productive. The following are general dietary
recommendations for all stone formers regardless of the type of their stone.
This is probably the most important of all dietary changes that may influence
your stone recurrence. Low fluid intake makes urine more concentrated and more
acidic both of which may promote stone formation. High fluid intake has been
shown to reduce the risk of stone formation in several ways. The amount of fluid
you drink should be enough for you to produce 2 liters of urine per day. You may
need to drink more water in the summer than winter. The kind offluid is not so
important, although it is better to drink non-dairy and low sodium fluids (e.g.
Gatorade and some sodas are high in sodium.) Water is best and a good starting
point is 6 to 8 full 8 oz. glasses per day.
Most people think that if they have had a kidney stone, they need to cut back on
their calcium intake. A low calcium diet may actually increase the risk of stone
formation in some patients. It has been shown that men on a high calcium diet
have 34% less risk of stone formation. Only few patients with calcium stones
will benefit from a low calcium diet. You need to be tested to find out if you
are among those. Some patients may need to increase their calcium intake in
order to reduce their risk of stone formation. Postmenopausal women who are on
calcium supplements have no increased risk of stone formation.
A high salt diet increases the amount of calcium ill the urine. This effect is
more pronounced in stone patients who have high calcium in their urine ( not all
stone formers have high urinary calcium.) It's recommended that all stone
formers cut back on the amount of their salt intake.
Incidence of kidney stones is higher in people on a high protein diet.
Vegetarians have a much lower incidence of stone disease. A high protein diet
increases urinary calcium, oxalate, uric acid, urine acidity and reduces the
urinary citrate .. All of these factors increase the risk of stone formation.
All stone formers are recommended to reduce the amount of their animal protein
intake. Of note, the amount of carbohydrate and fat in your diet does not
influence stone formation.
A few patients with calcium oxalate stones may have high oxalate in their urine
and may need to reduce the amount of their dietary oxalate. See table below for
a brieflist of high oxalate foods
A list of high oxalate foods
There is no association between alcohol consumption and stone risk. Chronic
alcohol use increases the amount of calcium and uric acid in the urine but these
patients are at no higher risk of stone formation. It's thought that the
increased urine production associated with alcohol use may be beneficial
prevention of stones.
Citrate is a naturally occurring substance in the urine that prevents stone
formation. The amount of urinary citrate can be measured in a 24 hour urine
collection. If this is found to be low, you will need to take a regular daily
medication. The amount of citrates in fruit is not high enough to raise urinary
citrate unless large amounts are taken everyday. In some patients with only
moderate reduction of citrate in urine drinking four glasses of lemonade
everyday may be enough to restore the citrate levels to normal.
All stone formers need to cut back on the amount of animal protein and salt in
their diet and increase their fluid intake. No change in calcium, oxalate, and
citrate is necessary unless you are tested and found to have a specific problem
Most stone formers do not need to be tested for these specific problems.
Recurrent stone formers or those at high risk of recurrence are usually tested.
What are kidney stones?
When certain substances in the urine become concentrated, they crystallize to
form rock like objects called stones. The vast majority of stones are formed in
the kidney and are calcium based (most common of which is calcium oxalate.) The
stones may stay in the kidneys and grow or they may get dislodged and pass down
the ureter into the
bladder. If a stone gets lodged in the
ureter urine backs up and stretches out the kidney like a water balloon. The
condition is called hydronephrosis
What causes kidney stones?
There are many factors that contribute to kidney stone formation. The most
common of which is the lack of hydration. If a person is prone to stone
formation and becomes dehydrated, his or her urine would be less dilute and the
concentrated substances would be more likely to crystallize into stones. Many
other factors like diet, anatomy of the urinary system and metabolism may be
involved. A strong family history of stone formation also increases the risk of
What are the symptoms?
A stone in the kidney mayor may not cause pain. Pain from kidney stones result
from blockage of urine flow and subsequent swelling of the kidneys. The pain is
usually located in the flank ( the part of the back just under the rib cage) but
may be felt in the groin when getting close to the
bladder. The pain usually
comes suddenly and can make the person feel nauseated. The pain can also
come and go over a period of time.
Some patients may pass blood in the urine. It's very difficult to predict which
stones will cause minor symptoms and which ones will cause severe symptoms.
The vast majority of stones will pass spontaneously. All smaller stones should
be given a trial of passage if the symptoms can be controlled with oral pain
medications. Stone passage depends on the size and location of the stone ( See
Tables 1 and 2.) In general the smaller the stone and further down the ureter,
the more likely it'll pass with observation. It may take as little as 1-2
days or up to 4-5 weeks to pass a stone. It's very difficult to predict how long
it'll take to pass a stone.
Size of Stone
Likely hood of passaze
Location of Stone
Likely hood of
Upper Ureter ( close
Lower Ureter ( close
There are many options available if a stone doesn't pass. The choice of
treatment modality is based on stone size
and location. Your-urologist can guide you in that respect.
ESWL ( Extracorporeal Shock Wave Lithotripsy)
This is a method where patients receive shock waves (non-electrical ) through a
water medium into the body and directed to the stone. The stone is fragmented
into many pieces with minimal injury to the body.
The pieces of stones are subsequently passed in the urine. There is no way to
predict on how good or bad stones fragment. The procedure is usually performed
under general anesthesia and is done mainly for stones in the kidney and upper
2. Ureteroscopy. This procedure is also done under anesthesia and involves
passing a scope into the bladder and up into the narrow ureter. It is usually
performed for stones in the lower ureter. The stones can be either broken up
into pieces by a laser or removed with a basket-like gadget. A stent ( a
temporary plastic tube) is usually placed after the procedure.
PCNL (Percutaneous Nephrolithotomy). This method is also done under general
anesthesia and involves placing a scope directly through the skin of your back
and into the kidney. The stones are fragmented through the scope by using
ultrasound and fragments sucked out. After the procedure a kidney tube is placed
temporarily through the skin and the patient usually stays in the hospital for
1-2 days. This is the most.invasive .of, all treatment modalities and is
generally reserved for larger stones.