What Are Kidney Stones?

Kidney stones are formed from the minerals and chemicals that are normally excreted by the body in the urine. When these chemicals crystallize and enlarge or stick to each other, they create stones. The composition of each stone will be different, depending on the specific chemicals involved.

What Are Kidney Stones Made Of?

Kidney stones are rarely made of only one chemical. Usually, there is a mixture of several different chemical components. The most common ingredient is calcium, but calcium does not form stones by itself. In stones, it's always combined with some other chemical, most often oxalate. Calcium stones are usually quite hard and they show up easily on X-ray. They generally respond relatively well to standard modern treatments. Calcium stones account for about 75 - 80% of all kidney stones and calcium oxalate is the most common stone component in 70%.

Oxalate is found mainly in edible plants, especially green leafy vegetables like spinach. It's also present in tea, chocolate and nuts. Excessive protein intake can also lead to increased oxalate production. Calcium oxalate stones can be caused by many different chemical and dietary problems such as low urinary citrate level or increased oxalate in the urine. That makes calcium oxalate stones very difficult to prevent unless a complete chemical profile is performed to identify all the potentially high risk factors. Calcium oxalate stones come in two forms. One is called calcium oxalate monohydrate, the other is dihycirate. The monohydrate form is particularly hard and difficult to fragment or crush. The dihydrate is much more brittle and fragments easily.

Calcium phosphate is a less common stone ingredient. When present calcium phosphate may suggest an underlying medical problem sucb as Renal Tubular Acidosis or Hyperparathyroidism. (Both of these conditions will be reviewed later in this section.)

Besides calcium, oxalate and phosphate, other common stone ingredients include uric acid, matrix, cystine or struvite. Uric acid is a waste product formed from purine which is a main ingredient in the genetic code material (DNA and RNA) present in every cell. When these purines are chemically digested, they produce uric acid. If our dietary protein contains genetic code material that has high levels of purine in it, we will make more uric acid. Vegetable proteins tend to have less purine in them than meat or animal proteins. High purine dietary proteins include poultry and fish, but red meat is usually the most often abused. The uric acid residue is excreted in the urine. Unfortunately, uric acid just doesn't dissolve well. It's ability to dissolve is very dependent on the acid content of the urine. When the acid level is high or if a large amount of uric acid is excreted all at once, uric acid crystals and stones will begin to form. Most stones that are "non-opaque" and don't show up on X-ray or are non-calcium containing will be composed of uric acid. Uric acid can be found in some calcium stones. It is thought that at times the calcium stones will form around a uric acid crystal nucleus, much like an oyster makes a pearl around a piece of sand.

Cystine is a normal body chemical that is actually an amino acid, one of the normal building blocks of protem. Some people have a congenital or genetic problem with cystine causing it to be excreted in large amounts in the urine. This type of stone is difficult to treat because it tends to be rubbery in texture and is often resistant to treatment. Fortunately, this is a rare type of stone.

Struvite stones are composed of magnesium ammonium phosphate. This combination is always related to infection. Without a urinary infection, this type of stone cannot form. Certain bacteria make a chemical enzyme that alters the urinary chemistry and reduces the acid content. Urine normally is slightly acidic. When this is normally acidity is lost, these infection or Struvite stones can form. Struvite stones can be large and difficult to eliminate.

The only way we can determine the exact chemical composition of your kidney stones is to make sure that every stone and stone fragment is collected and analyzed. That is why you should always strain all the urine to collect any stones or fragments that might pass for as long as necessary or until your physician tells you to discontinue. This is the only way to tell for sure how to stop forming more stones. Chemical testing of the blood and urine will show the possible risk factors and stone chemical analysis will demonstrate the final result but without indicating the specific chemical pathway. For a complete understanding of your chemical stone problem and a precise diagnosis, we need both the metabolic prevention testing and the stone chemical composition! So don't ever throw away any passed kidney stones!

How Do Kidney Stones Form?

When the concentration of the chemical waste products in the urine is higher than what can easily dissolve, crystals and stones will begin to appear. This process is obviously dependent on how much water is available to dissolve all the waste chemicals that the kidneys are trying to eliminate. when there is not enough water, stones will begin to form. This is why there is so much emphasis on increasing the urinary fluid volume since it will tend to dilute the chemicals that tend to form stones. It's like trying to dissolve a ten pound bag of sugar in a cup of coffee. There is just not enough fluid in just one cup to dissolve all that sugar. But if you throw that same ten pound bag of sugar in a swimming pool full of water, it will certainly dissolve. In order for a stone to form, there must not be enough water to dissolve all the chemicals and minerals the kidneys are trying to eliminate through the urine.

The concentration of some of these chemicals even in normal people is very close to the level at which stones and crystals would begin to form. Fortunately, there are chemicals that the kidneys put into the urine that seem to specifically block the formation of stones and crystals. These stone inhibitors, primarily citrate, are critical in preventing stone formation. Citrate supplements can be given to people who have insufficient urinary citrate to adequately block stone formation. Citrate will tend to lower the acid content of the urine (and raise the pH) which can help prevent calcium stones and even dissolve existing uric acid stones.

Other patients will absorb a higher percentage of minerals through the intestinal tract than the average person. These excess minerals will then be excreted by the kidneys and will tend to form new stones.

Why Do Men Have More Kidney Stones Than Women?

Men are generally bigger and heavier than women and have a larger lean body mass (muscles). Men will also tend to eat larger portions of red meat and animal proteins. This means that during a normal day's activity, men will create a greater amount of waste products that will need to be excreted by the kidneys through the urine. With more chemicals being discarded in the urine, it becomes more likely to exceed the dissolving capacity of the urine and begin the process of crystal and stone formation. It has been suggested that the male sex hormone, testosterone, may increase urinary oxalate and uric acid which will increase the incidence of stones. Finally, women tend to have slightly higher levels of citrate in their urine than men which helps block the formation of kidney stones.

Why Do Kidney Stones Hurt So Much?

A kidney stone pain attack, also called "colic", is described as the most painful experience it's possible to live through. It's more painful than gunshot wounds, major surgery, broken bones, burns and even childbirth. The pain is unrelated to the size of the stone and is not caused by the stone "moving" or scratching as many people believe. In fact, the pain is caused by the dilating or stretching and cramping of the urinary system caused by the blockage the stone produces when it gets stuck in the ureter. (The ureter is the muscular tube that drains urine from the kidneys into the urinary bladder.) When the urine that the kidney produces cannot pass the blockage, the ureter and urinary system stretch. The ureter is composed of muscle and will contract or cramp when stretched. This stretching, dilating and cramping is what causes the intense pain. (The same process causes the pain from intestinal gas that we all get from time to time.) This also explains why the stones usually don't cause pain when they are just sitting inside the kidney. Since they don't produce any blockage, stretching or dilating of the urinary system, they don't usually produce any pain until they pass out of the kidney and get stuck. The degree of pain is unrelated to the size of the stone which is why it is possible to have excruciating pain from a stone smaller than a grain of rice. Typically, the pain will start in the upper back on the side of the affected kidney. The pain will then travel or radiate down and around the flank or side and head towards the groin. Most people can correctly identify the exact site of their stone just by pointing to where the pain is worst.

Fortunately, many small stones will pass without the patient even knowing it. The pain from a stone attack, even when very severe, will usually pass in about 24 hours. This is because the urinary system will reach a point where some urine sneaks around the obstructing stone and the stretching and cramping will stop. Just because the pain may go away does not necessarily mean that the stone is gone. Usually an X-ray will be needed to determine if in fact the stone is still present or not. Stones can fragment in the system so even if you pass one "stone" another fragment may remain inside. In the past patients with colic were routinely admitted to the hospital so they could receive strong pain medicine usually by injection. Now we only bring patients into the hospital when we cannot manage their pain adequately with oral medications alone or if there is a potential complication such as an infection, a solitary kidney or a pregnancy. Even then, patients often stay only 24 hours or less in the hospital on "observation" status. Fortunately, most patients do not have to stay in the hospital very long and many can be safely sent home from the Emergency Room once a diagnosis is made and initial treatment begun.

Some stones will get stuck in such a way that they will cause an intermittent problem. This is sometimes called a "ball-valve" since the pain can and usually does return quickly between attacks.Since no equalization occurs, this type of intermittent pain attack can continue much longer than 24 hours.

There are three areas in the urinary system where stones are most likely to get stuck and cause a blockage. The first is just where the central collection sack of the kidney joins with the top of the ureter. (The ureter is the muscular tube that drains urine from the kidney to the urinary bladder.) This area is called the Ureteropeivic Junction or "UPJ". This structure is normally a wide open funnel shaped cone, but some people are born with an anatomical narrowing at this point. Stones that get stuck here will likely get stuck somewhere else downstream, so we often will try to do some treatment of the stone relatively quickly. Stones can be blasted with "ESWL" easily here, although the best location for ESWL is in the kidney itself. (Actually, it's possible to use ESWL on any part of the urinary system, but most experts agree that the kidney is the ideal stone location.) The next area of increased risk is about two thirds of the way down the ureter towards the bladder. This is where the ureter bends to pass over the large blood vessels taking blood to the legs. The narrowest part of the ureter is where it attaches to the bladder itself. This is called the Ureterovesical Junction or "UVJ". The ureter passes through the muscular wall of the bladder at a steep angle. This anatomy works as a valve to keep urine from backing up into the ureter every time the bladder contracts during voiding. Even a relatively small stone here can easily become stuck. Irritation of the bladder wall will cause many people to have cramps or spasms of the bladder and urinary frequency if a stone is stuck here.

If a stone is not causing any blockage and there is no infection, then there will not be any pain from that stone. There must be blockage or infection for a stone to cause pain. Sometimes, just after a stone has passed, there will be some residual inflammation and partial blockage. In these cases there can be some temporary pain or discomfort. But in general, there must be either obstruction to the urinary system or infection for a stone to cause pain.

Will My Stone Pass Without Surgery?

If the stone is smaller than 5 mm or about 1/4 inch in diameter, then it will probably pass without surgery. Should your stone be greater than 10 mm or about 1/2 inch in width, then it almost certainly will not pass. Stones that are between 5 and 10 mm may pass but it's increasingly unlikely as the stone gets larger. Whenever possible, we like to give the stone every chance to pass by itself before resorting to surgery.

What Are My Chances of Having Another Stone Attack?

If there are no additional stones in your kidneys now and this was your first stone attack, then your chances of forming another stone is about 10% a year although this will vary according to the specific chemical problems that are involved with each individual patient. Younger patients and those with a close family member or blood relative with stones are at greater risk. The peak ages for kidney stone production are between twenty and forty years of age. On the average, the risk of having another stone problem if you've just had your first stone attack is about 70-80%. If you live in the V' Stone Belt V', then your chances will be higher. A white male, your chance of having at least one stone by age 70 is one out of eight.

Can't You Dissolve The Stone With Medicine?

Unfortunately, most stones are made of a variety of calcium mineral combinations that can't be dissolved with any known medicine. About 10% of all stones are made up of uric acid. Only these pure uric acid stones can sometimes be dissolved with proper medication. But the majority of stones are made of calcium which cannot be dissolved. But we do have many methods for getting rid of kidney stones relatively painlessly, such as ESWL which stands for Extracorporeal Shock Wave Lithotripsy (commonly known as the "Stone Machine".)

If I Get A Stone Attack, What Should I Do?

It may not be easy to tell if you're having a kidney stone attack or some other potentially serious medical problem. The best policy is to go direcfly to a hospital emergency room. (Urgent care centers and physician's offices may not have the diagnostic testing available to make a definitive diagnosis and you might end up being transferred after much delay to a hospital anyway.) Only about 50% of the cases of severe flank and abdominal pain that start out as possible kidney stone attacks actually turn out to be true stone events! The rest can be other medical problems such as appendicitis, bowel disease, intestinal obstruction, ulcers, abscesses and a variety of other medical diseases and conditions.(See section on Diagnosis)

There are several symptoms that clearly indicate the need to go to the hospital.

-Severe pain not controlled by oral pain medication.
-Fever.
-Persistent vomiting.
-Unable to take oral fluids.
-Severe or persistent diarrhea.
-History of a solitary kidney, kidney failure or pregnancy.

You cannot make the diagnosis of kidney stones yourself. Even if you're sure the pain is identical to your last stone attack, you could be wrong and have to suffer the consequences if it just happens to be your appendix.

ALWAYS HAVE THE PROBLEM CHECKED BY A PHYSICIAN!

What About Using The "Stone Machine" To Break it Up?

The "Stone Machine" or ESWL, fragments stones by using shock waves. The original machine produced shock waves with a special spark plug located at the bottom of a tank of water. These shock waves are then focused at a predeterniined spot in the tank. The patient is anesthetized and placed on a special frame which is lowered into the tank. The patient and frame are then gently maneuvered inside the tank until the stone is positioned precisely at the focal point of the shock waves. X-rays are used to pinpoint the location of the stone and to make certain it remains exactly at the correct spot. The shock waves literally vibrate the stone so intensely it eventually shatters and fragments without injury to the surrounding tissues. In order to use the machine, the stone needs to be large enough to be seen clearly under the X-rays used for positioning. The stone also has to be in a location such as the kidney where the shock waves can reach it easily without striking bone.

Many newer machines have eliminated the water tank and do not require ftlll anesthesia. Most of these newer machines are not as powerftil as the original so there is a greater chance that a second treatment will be needed before all the stone material is completely fragmented.

It can take three months or longer to pass all the stone fragments after a successful treatment and there is a weight limitation on most available machines of 300 pounds. Patients who weigh more may not be able to use this technology.

What Kind of Diet Should I Eat To Avoid More Stones?

This is probably the question we get asked most often. There is no easy answer to what type of diet you should follow. It depends on the type of stones you are making and the chemical abnormalities and risk factors your body produces The only way to tell for sure is to analyze any stones or stone fragments that have been collected and to perform a comprehensive blood and urine chemical testing series designed to show the specific problems in your particular case. Then, specific recommendations can be made.

However, if you really need an answer, we can make a few general recommendations. First, drink more water and fluids. There was probably not enough urinary volume to dissolve all the chemicals the kidneys were tlying to get rid of at some point. Secondly, as far as the rest of the diet, the best advice is avoid excess in all the types of food you eat. Excessive salt, fat and meat protein should probably be avoided. But with fifty separate potential stone composition chemicals and over sixty five different medical problems, conditions, deficiencies, excesses or disorders that can contribute to stone disease, it's easy to see that no single piece of advice is likely to help every situation. Therefore, we urge every patient interested in stone prevention to get properly tested and treated by a physician interested and knowledgeable in kidney stone disease prevention.

Why Limit Salt (Sodium) And Meat Protein?

Excess dietary salt (sodium) will tend to promote kidney stone formation primarily by increasing urinary calcium excretion. Sodium will change the way that calcium is excreted by the kidneys. The higher the sodium load, the greater the amount of calcium that will appear in the urine. It may also decrease urinary citrate, an important kidney stone inhibitor.

Excessive meat protein in the diet will tend to increase urinary calcium, oxalate and uric acid levels as well as make the urine more acidic. All of these changes will increase the risk of kidney stones. When meat protein is fully digested, it tends to leave an acid residue which is excreted by the kidneys. Uric acid is a waste product made from the chemical digestion of purines, a component of the genetic code material inside all living cells. Those proteins that have high levels of purine will create higher levels of uric acid. These high purine proteins are red meat, pou1itry and fish. Vegetable protein has much lower levels of purine than animal protein. Uric acid can form stones by itself and promote the creation of calcium stones by forming tiny crystals or stones which quickly become covered with calcium compounds is susceptible people. Some stone patients will stop making stones if they can simply control their excessive dietary meat protein intake.

What About Just Limiting My Intake of Calcium and Dairy Products?

Many kidney stone patients severely restrict their calcium intake without realizing that such a reduction in dietary calcium can actually increase their risk of calcium stone disease. Dietary calcium has an important role to play in binding other minerals within the intestinal tract. A significant reduction in calcium intake can cause an increase in absorption of some of these other minerals which are normally bound or attached to the calcium. When not enough calcium is available for these minerals to bind to, they are left free to be absorbed by the body and eventually excreted in the urine where they can help form new stones. The net result is an increase in the risk of forming more calcium stones if calcium intake is restricted too severely!

Dairy products not only contain a relatively large amount of calcium, but they are also rich in phosphate and magnesium, two important kidney stone formation blockers. Eliminating dairy products would therefore cause a decrease in these two important stone prevention chemicals.

Finally, when you eliminate calcium from the diet, the intestinal tract attempts to compensate by increasing the rate or percentage of calcium absorption. (Normally, we only absorb 3045 % of the calcium we eat.) If you should "cheat" and actually eat a high calcium meal when the intestinal tract is in this higher absorption, sensitized condition, the amount of calcium actually entering the body would be much higher than normal. A sudden calcium load may begin the formation of a new kidney stone.

How Can I Avoid Getting More Kidney Stones?

While we have excellent methods of fragmenting stones with shock wave machines, lasers and internal lithotriptors it's much more efficient and cost effective to eliminate the true, underlying causes of kidney stone formation whenever possible.

The first essential step in the prevention of kidney stones is to guarantee that there will always be sufficient water intake to produce enough urine to easily dissolve all the minerals and chemicals the kidneys normally produce and excrete. In other words, if you could drink enough water and liquids to always keep the chemical and mineral content of the urine from becoming too concentrated, you would never form any kidney stones. Without sufficient fluid intake, no prevention program has any chance of success.

In general, we recommend increasing fluid intake throughout the day and dietary moderation of most food groups. Patients should also avoid excessive dietary intake of dairy products (calcium), meat and salt.

The only way to identify the specific chemical or mineral imbalances that contribute to kidney stone formation in any individual patient is to perform a comprehensive series of blood and urine chemistry tests. This preventive testing series, called Metabolic Analysis or Metabolic Testing, is absolutely essential in order to identify the specific risk factors in a particular patient. Knowing the chemical composition of any previous kidney stones or stone fragments is extremely helpfull, but without a Metabolic Testing Program it is impossible to identify the particular cause of an individual's production of stones.

Therapy usually consists of various but specific dietary adjustments or nutritional supplements.Sometimes medication is required when dietary treatment alone has failed to correct the chemical imbalance. The patient must be motivated to follow treatment suggestions for an indefinite period for any prevention program ultimately to be successfiil.

Conservative treatment measures such as dietary moderation and increasing fluid intake can reduce recurrences by about 60%. Metabolic Testing consisting of comprehensive blood and urie chemistry analysis, together with a specific treatment plan can reduce the risk of new stone formation by up to 98%! Metabolic testing is now available nationwide. A physician's order for the testing will be necesary.

INCREASING URINARY VOLUME
Stephen W. Leslie, MD FACS Urologist

An adequate urinary volume is absolutely essential for the prevention of kidney stones and recurrent urinary tract infections. The average 24 hour urinary volume in normal people is about 1300 cc's per day. Patients with kidney stones or recurrent urinary infections should produce about 2000 cc's or a little more than 2 quarts each day. A low urinary volume will significantly increase the concentration of calcium, salt and other minerals predisposing to kidney stone formation and bladder irritation. A high enough urinary volume can reduce the bacterial count of the urine and actually cure mild bladder infections by getting rid of the bacteria faster than they can multiply. The obvious way to achieve this is to increase oral fluid intake but this is often difficult for many patients. We therefore suggest the "I.R.S. Plan" for increasing fluid intake and urinary output.

At least half of any increased oral fluid intake should be water. This is what the body was designed for. As a general rule, the urine should appear no darker than a very pale yellow. To keep track of the urinary output, collect all the urine for 24 hours in a half gallon milk container. If you can fill the container in just one day, then the urinary output is probably adequate.

The "IRS Plan" (Internal Renal Stones) may be the easiest way to significantly change your fluid intake. The "IRS Plan" consists of a "Kitchen Tax, Meal Tax, Nighttime Bathroom Use Tax, Penalty Tax, Restaurant Tax, Snack Tax, Summertime Tax, Time Tax, Work Tax and Water Fountain Tax!" You should add as many "taxes" as necessary to reach and maintain the desired level of urinary volume. The "tax" in the plan consists of a glass of water or other suitable liquid. The size of this additional glass will need to be adjusted between 4 and 12 ounces to maintain the urinary output at the desired level. We suggest that you start at just 4 ounces and let your body adapt to the increased fluid. Depending on your individual tolerance and metabolism, your system will gradually adjust to the increased fluid and you will become thirsty if you fail to keep your fluid intake up. This usually takes about a month of regular increased fluid intake. Until your internal fluid "barometer" is reset, it may be difficult to maintain the increased fluid intake, but your system will start to adjust in just a few weeks.

"Kitchen Tax" = One glass whenever you've entered your kitchen and wish to leave. (This is more of a "toll" than a "tax".)

"Meal Tax" = One extra glass with each meal except if you eat out at a restaurant where you will need two extra glasses.

"Nighttime Bathroom Use Tax" = One glass whenever you get out of bed to go to the bathroom at night. (We don't usually drink very much at night when we're asleep. With this tax, if you're already up anyway, you might as well add that extra drink of water.)

"Penalty Tax" = If you eat or drink a food item you've been instructed to avoid or limit, you must drink at least two extra glasses.

"Restaurant Tax" = When you eat out at a restaurant you need to double the meal tax to two glasses. (This is because restaurant food is high in salt which causes you to retain water)

"Snack Tax" = At least one extra glass if you have a snack between meals or at bedtime.

"Summertime Tax" = During the summer months or whenever the outside temperature is over 75 degrees, you must double all the other taxes!

"Time Tax" = One glass if you've managed to avoid all the other taxes for at least two hours.

"Water Fountain Tax" = Whenever you pass a water fountain, you are required to take a drink consisting of at least 10 swallows.

"Work Tax" = One glass whenever you leave your designated work area or desk.

A FEW OTHER SUGGESTIONS TO HELP INCREASE URINARY VOLUME

Substitute high fluid content desserts in place of pastries, cookies and cakes. Frozen ices, sherbet, melons and fruit are recommended.

Maintain the humidity level in the home and workplace between 40 and 45 percent to minimize fluid loss through the skin and from just breathing.

Drink a full glass of water whenever you take any medication. Limit your salt or sodium intake. Salt in your food can cause you to retain fluid and make your urine more concentrated. Avoid heavily seasoned and processed foods and do not add any additional salt to your meals.

If these suggestions fail to adequately increase the urinary output, a diuretic can be used as a last resort. This will force a mandatory increase in urinary volume but can cause mineral and salt imbalance in the blood and a number of other complications. Failure to increase fluid intake while taking a diuretic could lead to dehydration.

It is rarely necessary to resort to all of these measures to increase the urinary output adequately. Check your progress by measuring the urinary volume and add as many "taxes" as necessary to achieve an optimal total volume. This will reduce your risk of recurrent infections and particularly of kidney stones. Good Luck!