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The Kidney Stone WebSite by Roger Baxter
An Educational Resource for Sufferers with Kidney Stones
by Roger Baxter
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Recurrence of Kidney Stones
The chance of having recurring stones are about 70-80 percent once a person suffers their first stone attack. After the first kidney stone attack occurs in a person they have a cumulative 10 percent chance per year of forming another stone (if no other stones are present at the time of the first stone attack). This translates into a 50% chance over a 5 year period of time. Family genetic tendencies can increase this risk.

The younger a person is when they have their first kidney stone attack the greater their personal risk of having additional attacks. Those between the ages of 35 and 50 are in their peak stone formation period.

Historically about 60 percent of individuals who have experienced one kidney stone will develop another within 7 years. But whereas just a few years ago recurrence of kidney stones was unavoidable, modern medical science has made recurrent kidney stones a preventable disease. With individualized medical therapy recurrence can be prevented in more than 95 percent of suffers.

Chemical Composition of Kidney Stones
Knowing which one of the several types of chemical composition has caused a suffer's kidney stone to form will allow medical treatment to prevent that particular type of stone and thereby prevent recurrent kidney stone attacks. Therefore it is very important to catch the stone - when and if it is passed - so that it can be chemically analyzed.

Most stones are made up of calcium or a combination of calcium and oxalate. These stones show up quite well on x-rays. Calcium mineral combination stones cannot be dissolved with any known medicine. However kidney stones made up of uric acid are invisible to x-rays, but can sometimes be dissolved with the proper medications.

  • Common Chemical Make Up:
    • calcium phosphate (8%)
    • calcium oxalate (most common: 73%, most opaque)
    • magnesium ammonium phosphate (also called "struvite" - often caused by an infection)

    Uncommon Chemical Make Up:

    • diammonium calcium phosphate
    • magnesium phosphate

    Rare Chemical Make Up:

    • cystine (faintly opaque; 1%)
    • urate (lucent - meaning translucent to x-rays; 7%)
    • xanthine

A series of nine magnified PHOTOGRAPHS of these various types of stones is available online from Herring Lab, the company who analyzes more kidney stones than any other - over 125,000 per year.

The southeastern area of the United States is known as the Kidney Stone Belt because of the relative high ratio of people suffering from kidney stones in those states. North Carolina (where this author, a fellow kidney store sufferer happens to live) has more kidney stone cases per capita than any other state. Several factors probably come into play to create this situation. One is the typical southern diet which is high in green vegetables and brewed tea - both of which are high in oxalates. The second is the hot climate which causes increased amounts of perspiration and loss of body fluid. And finally, modern life styles often reduce physical activity.

Together these factors put people at high risk for kidney stones. Oxalate from foods is usually present in urine. The oxalate forms a salt with calcium that has a low soluability factor (it does not dissolve easily; it does precipitate into crystals easily). Even mild chronic dehydration can increase the likelihood of kidney stone formation. Inactivity has been associated with increased kidney stone formation: Russian astronauts in space for long periods have developed kidney stones. Thus a southerner with high levels of oxalate combined with chronic dehydration and a sedentary life style is more likely to suffer from their increased risk of forming kidney stones.

Vitamin C and Vitamin D increase the formation of oxalates during the food digestion processes. (Not only do certain foods contain oxalate, additional oxalates can be formed as a byproduct of the natural metabolic process.)

Preventing Kidney Stone Formation
The easiest step to take is to increase hydration. This applies to sufferers of all types of kidney stones. Drinking very large amounts of water - two or more quarts per day - is probably the most important step in reducing stone formation. It is recommended that sufferers increase their urine output to at least 2 quarts per 24 hour period. Drinking 2 to 3 quarts per day may reduce recurrence of stones by up to 90 percent.

Initially many kidney stone sufferers may find it difficult to raise their fluid intake to this level. However, with a consistent conscious effort a person will develop a taste for water. After about a month their body will readjust its normal level of hydration. Once this new norm has become established a person will start to feel thirsty whenever their fluid intake falls below this level. Some tips on increasing fluid intake may prove helpful. One kidney stone sufferer says: I like water now. You acquire a taste for it.

High calcium in urine can be caused by too much salt in a person's diet. Salt causes excretion of larger amounts of calcium and thus increases calcium in the urine. Increasing a person's intake of water will reduce the relative concentration of calcium in the urine and thus reduce the risk of crystal formation and kidney stone formation.

Additionally, persons prone to the most common type of kidney stones (calcium oxalate) may find it advisable to cut back on foods with high oxalate levels such as those listed below to help prevent future stone formation:

  • apples
  • asparagus
  • beer
  • beets
  • berries, various
  • black pepper
  • broccoli
  • cheese
  • chocolate
  • cocoa
  • coffee
  • cola drinks
  • collards
  • figs
  • grapes
  • ice cream
  • milk
  • oranges
  • parsley
  • peanut butter
  • pineapples
  • spinach
  • Swiss chard
  • rhubarb
  • tea
  • turnips
  • vitamin C
  • yogurt

Stone suffers should consult with their doctor, of course, but in most cases, these foods can be eaten in limited amounts.

A diet with high levels of sodium, sucrose, or animal protein increase the likelihood of kidney stone formation. Conversely, high levels of potassium, magnesium, and fluids lower the likelihood of kidney stone formation.

The Division of Urology at the Toa Payon Hospital in Singapore offers dietary advice for kidney stone patients including both what to eat as well as what not to eat. There are, also, medications available to reduce the tendency towards formation of certain types of stones.

One type of medication to reduce risk of formation of calcium oxalate stones introduces high levels of citrate into the kidneys. This citrate in the urine reduces the tendency for calcium oxalate stone formation. A similar increase in urinary citrate is generated by drinking lemonade (lemons are one of the good foods) containing at least 4 ounces of lemon juice per day.

It has been discovered that avoiding calcium may do more harm than good when it comes to kidney stone sufferers who have, in the past, been warned to avoid foods rich in calcium. According to a study of over 45,000 men conducted by the Harvard School of Public Health, men who get lots of calcium in their diets have a one-third lower risk of having kidney stones than do those who consume calcium sparingly. It seems that high dietary calcium actually blocks a chemical action which causes the formation of kidney stones by binding with oxalates (from foods) in the intestine which then prevents both from being absorbed into the blood stream and later transferred to the kidneys. Urinary oxalate may be more important to formation of calcium-oxalate kidney stone crystals than is the urinary calcium.

However it must be quickly noted here that calcium supplements increase kidney stone risks according to the Annuals of Internal Medicine, March 1997. High normal dietary calcium reduces kidney stones by 35 percent, but high calcium from non-foods - like calcium supplements - actually increase the risk of kidney stones by 20 percent.

That same Harvard study found that:

  • Those with the highest consumption of potassium, from eating fruits and vegetables, had only half the risk of stones;
  • A high fluid intake was associated with a 29 percent lower risk; and
  • Those who ate the most animal protein had a 33 percent higher risk of developing kidney stones.

Winning the battle with kidney stones is a two stage war. The first hurdle - which is sometimes elected to be skipped by doctors and patients - is to become stone free to reduce later stone formation due to the presence of those existing stone crystals. Then the second hurdle is to eliminate (or at least reduce) the risk factors that might lead to formation of new kidney stones.

A review of the information on kidney stones every 3 to 6 months may be necessary to keep the benefits and importance of constant and long term viligence at the stone prevention process in the sufferer's conscious mind. To assist your remembrance you can be periodically alerted to updates to The Kidney Stone WebSite by registering with the NetMind service below.


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Why Be Concerned
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History of 'The Kidney Stone Web Site"
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Latest update January 6, 2006