Kidney Stones: Preventing a Recurrence
Q: A few months back, I suffered from an excruciatingly painful kidney stone
attack. My doctor told me that once you have one, there's a good possibility
that at some point you'll have another. Is there anything I can do to
prevent another agonizing episode?
Dr. Donnica: There's a good chance that you may have a recurrence,
but also a good chance that you won't. While up to 10% of Americans pass
kidney stones, half of them will not pass another. Kidney stones ("nephrolithiasis"
or "urolithiasis") are abnormal, hard, chemical deposits that form
inside the kidneys. They may be as small as grains of sand and pass through the
body in urine without any discomfort. The stones of concern, however, are significantly
larger. While some of these larger stones are too big to pass, some may get into
the narrow tube between the kidney and bladder (ureter), and get trapped. This
causes severe symptoms, including extreme pain, blocked urine flow and urinary
There are several different types of stones. Prevention strategies are based
on the type of stone you had, so this is an important discussion to have with
your doctor. Certain medications may increase the risk of stone formation, so
your doctor will review all of the medications and supplements you may be taking.
There are also medications, which may reduce the risk of some types of stones.
The most common kidney stones are composed of calcium oxalate. In half of the
people with these stones, formation is due to an increased level of urinary
calcium, which may be genetic. Calcium stones are caused by an overexcretion
of oxalate, a hormone imbalance, bowel disease or kidney problems.
Prevention strategies include drinking plenty of water and other fluids (so
that your urine is clear). Water is good, but fluids high in citrate (e.g. lemonade)
are better. Citrate acts as a stone formation inhibitor. Aim for a low-sodium,
low-protein diet: cut back on salt, meat, fish, and chicken.
The role of dietary calcium after having kidney stones is controversial. Some
patients need to reduce calcium intake, but most patients are advised to eat
a normal amount of low-fat dairy products, but avoid calcium supplements. Dietary
calcium binds oxalate and reduces the amount excreted. Most patients who have
had kidney stones should also avoid eating foods high in oxalate: beets, spinach,
chard and rhubarb. Tea, coffee, cola, chocolate and nuts also contain oxalate,
but these can be used in moderation.
Created: 1/8/2005  - Donnica Moore, M.D.