Kidney Diseases

Diabetes is the most common cause of chronic kidney failure in Singapore. It accounts for up to 50% of new patients with end stage kidney failure. Because there is no definite cure as yet for diabetes, prevention of kidney related complications is crucial.

WHAT IS DIABETES MELLITUS?
Diabetes Mellitus, or simply called “diabetes” is a disease where the body is unable to make insulin or unable to utilize the insulin secreted from the pancreas properly resulting in glucose buildup in the blood. Insulin is a hormone that regulates the amount of sugar in the blood.

There are two types of Diabetes:

Insulin Dependent Diabetes Mellitus (IDDM) or Type 1
Usually occurs in children, also known as “juvenile diabetes”. The pancreas produces little or no insulin. People in this group require daily insulin injection.

Non-Insulin Dependent Diabetes Mellitus (NIDDM) or Type 2
Usually occurs in persons over 40 years old, also known as “adult onset diabetes”. The pancreas produces insulin but the body is unable to utilize it properly. Blood sugar can be controlled by diet and/or medicine, although some may require insulin.

How does diabetes affect your body?
Uncontrolled glucose level in the blood causes changes and damages the blood vessels. This affects not only blood vessels in the kidneys, but also blood vessels in other organs such as the eyes, skin, nerves, intestines, muscles and the heart. Both large and small vessels are affected. It is common to find patients who have had longstanding diabetes requiring amputation of a leg because of insufficient blood supply and infection.

What does diabetes do to the kidneys?
In diabetic kidney disease, there is obvious involvement of the glomeruli. The glomerulus is a ball of blood vessels, which act as the filtering units in the kidney. Early involvement shows up as leakage of protein in the urine. In medical terms, this is called “proteinuria”. As proteinuria becomes more severe, functions of the kidney such as balance of salt and water become deranged causing salt and water retention. The patient then will notice some weight gain and swelling especially in the face in the mornings and legs later in the day. In more advanced stages, the kidney filters become totally destroyed leading to a state of kidney failure.

Diabetes may also damage nerves. There may be difficulty in emptying the bladder as this depends on intact reflexes from the nerves and coordination between nerve and muscles of the bladder. The pressure from an overfull bladder can ‘push’ urine backwards towards the kidneys causing injury. If urine remains for a long time in the bladder because of incomplete emptying, one may get a urine infection. 

What are the signs of kidney disease in patients with diabetes?
Early stages of kidney involvement without kidney failure are characterised by:

• Protein in the urine
• High blood pressure
• Ankle and leg swelling
• Frequency of urination especially at night

• Water retention becoming more resistant to medication
• Poor appetite, nausea and vomiting
• High level of urea and creatinine in blood
• Weakness and pallor from anemia
• Itching

What can patients with diabetes do to prevent kidney damage?
The risk can be lowered by:

• Good control of diabetes by a combination of a diabetic diet and medication if necessary
• Good control of blood pressure
• Regular follow up to monitor if the control is adequate

If kidney involvement has already been diagnosed, does this mean I have kidney failure?
No, kidney function is normal at first. It takes a few years before early involvement leads to kidney failure. While there is no cure, there is time to slow down the process with treatment.

What specific measure can be taken to retard the progression to kidney failure if the kidney function is still normal?
Diet
Continue with your special diabetic diet as before. Further dietary modification may be necessary especially with respect to salt, amount of fluid consumed and potassium.
Your doctor will advise you on your fluid allowance and diet restriction. The dietitian will help you to plan your diet according to the stages or severity of the disease process.

Will dialysis be needed if the diabetic patient starts to have kidney failure?
No dialysis is required in early kidney failure. It will be needed in advanced kidney failure when the state of “end stage kidney failure” is reached. Generally, it means that the kidneys are functioning at less than 10% of its original capacity. The progression of kidney failure from its early stage to advanced stage can be retarded with drugs and proper dietary restriction so it is important that a diabetic patient maintain close follow up with his or her doctor.
If dialysis is deemed by your doctor to be required soon, you should also discuss with him the option of a kidney transplant instead of long-term dialysis treatment.

You may visit these websites for more information:
http://www.davita.com
http://www.uptodate.com/patients/index.html

Glomerulonephritis is the second most common cause of kidney disease in Singapore, the first being diabetes mellitus.

What is glomerulonephritis?
Glomerulonephritis means inflammation and scarring of the kidney filters. There are different types of glomerulonephritis. Infections by bacteria, virus and parasite can cause glomerulonephritis through its effect on the immune system. Autoimmune diseases such as systemic lupus erythematosus (SLE) and IgA Nephropathy are other types of glomerulonephritis. In Singapore, IgA Nephropathy is the most common form of primary glomerulonephritis.

How does glomerulonephritis come about?
When a person has infection or autoimmune disease, the fighter cells in the body react to cause antigen and antibody complexes to form in the blood stream. When the blood with these complexes reaches the kidney filters (glomeruli), the filters become inflamed and scarred from the insult. In severe cases, kidney filters die and the ability of the kidney to remove the extra waste products and water decreases.

- How are these antigen and antibody complexes formed?

Antibodies are made by the body in an attempt to eliminate foreign matter (antigen). An antibody is an agent, which can attach to an antigen that it is trying to destroy, thus forming antigen and antibody complexes. When the immune system is over-reactive, abnormal antibodies or abnormally high levels of antibodies are produced. Other problems include an inability of the body to clear these complexes from the blood stream. In many types of glomerulonephritis, the antigen is often not known. Occasionally the antigen is the body’s own tissues or even the kidney itself. It is often not clear why these complexes form.

What are the signs and symptoms of glomerulonephritis?
Glomerulonephritis usually has no signs and symptoms until the kidney filters are damaged. Therefore, if the disease is in an early stage, it is usually detected following pre-employment or life insurance screening as presence of blood or protein in the urine. In Singapore, cases of young men with glomerulonephritis are picked up through a routine medical examination during their National Service. Some other types of glomerulonephritis are associated with skin or joint disorders and may be detected when patients seek treatment for their joint or skin problems.

When the kidneys are severely damaged, a person may present with complaints related to kidney failure, which include:

• Headache, nausea, vomiting, fever, chills.
• Less urine output because of reduced urine production.
• Swelling especially in the face, hands and feet (edema) due to water and salt retention.
• High blood pressure which is > 130/80 mmHg (Hypertension).

What investigations are performed to identify glomerulonephritis?

• Urine sample to check for presence of blood protein.
• 24 hours urine collection and blood samples to assess kidney function and amount of protein passed out in the urine.
• A renal biopsy (a tissue taken from the kidney) to determine the type of kidney disease. It is usually done when the disease is more advanced and more specific treatment options need to be considered.

If the person has been diagnosed with glomerulonephritis, what can be done?
Often there is no cure for chronic glomerulonephritis. However, the inflammation can be controlled and progression of damage to the kidneys can be slowed down.

What are the types of treatment available to slow down the progression of damage to the kidneys?
In a very mild case, no treatment is necessary. Your doctor will let you know what stage of glomerulonephritis you have.

For moderate and advanced cases treatment includes:

Drug Therapy

• Treatment of high blood pressure with antihypertensive reduces stress to the kidney filters.
• If there is fluid retention, diuretics will help to get rid of the excess water and salt. The drug causes a lot of urine to be passed out.
• Reduce the leakage of protein with certain classes of anti - hypertensive called ACE inhibitors or Angiotensin II receptor blockers. These drugs reduce the leakage of protein into urine.
• Anti-platelets (dipyridamole) and anti-coagulant (warfarin) have been shown to be effective in IgA Nephropathy.

Dietary Measures

• Control salt and water intake to prevent fluid retention.
• Control potassium intake to prevent abnormal heart rhythm.
• Control protein intake to reduce stress to the kidneys. There is a very fine balance between too much protein, which can stress the kidney, and taking too little, which can lead to malnutrition. It is very important that you see the dietician so that she can assess and advise you on the correct amount to take.

When will a patient with glomerulonephritis have kidney failure?
The time it takes for a glomerulonephritis to cause kidney failure is usually many years. Because there are often no symptoms, many people do not know they have glomerulonephritis. Even when tested positive for urinary abnormalities this is ignored as there is often no pain or swelling seen. A mild case in which no treatment is required can progress to a more serious stage requiring treatment. Those on treatment may default because the patient feels well. The opportunity to control the illness is then missed because when symptoms surface the patient may already have kidney failure.

What are some points to remember if one is diagnosed with glomerulonephritis?
It is therefore important to remember the following points:

a) Mild cases

Even if there is no treatment, monitoring on a yearly basis is necessary with your family doctor. If the urine protein becomes excessively high, you should come back to the hospital for further assessment.

b) Moderate to advanced cases

Medication would usually have been started. Follow up should continue and monitoring of the degree of protein leakage, kidney function and complication of the drug treatment should be done periodically. Prevention of kidney failure is the goal, as treatment of advanced kidney failure is time consuming and very expensive.

Remember, the whole process occurs over a long period of time, thus follow up and compliance to treatment is essential in preventing kidney failure.

You may visit these websites for more information:
http://www.davita.com
http://www.uptodate.com/patients/index.html

THE URINARY TRACT SYSTEM
The urinary tract begins in the kidneys where urine is produced. Urine then drains through the ureters and stored in the urinary bladder until it is passed out through the urethra.

WHAT IS A KIDNEY STONE?
A kidney stone is a solid mass which forms in the urinary tract due to crystallisation of substances present in the urine and can be found along any part of the urinary tract. Kidney stones may stay in the kidneys or break loose and travel down the urinary tract. A small stone may pass out of the body spontaneously. On the other hand, a larger stone may become lodged in the ureter, bladder or urethra. Stones may also obstruct the flow of urine and cause pain although many can exist without symptoms. Stones that obstruct or cause repeated or severe infections may lead to kidney failure.

HOW DO KIDNEY STONES FORM?
Many risk factors lead to stone formation. Some of these include:

• Drinking too little fluid 
• Family history of stones 
• Previous history of urinary tract infections or stones 
• Certain metabolic conditions

TYPES OF STONES
There are four main types :

• Calcium Containing Stones (most commonly calcium oxalate)

These may form for a variety of reasons including low fluid intake, high excretion of calcium, uric acid and/or oxalate in the urine. A high amount of dietary salt also leads to increased calcium in the urine.

• Infection Stones

These are of a mixed nature containing magnesium ammonium phosphate (also called struvite) and calcium carbonate. They are associated with infection by certain bacteria only.

• Uric Acid Stones

Too much acid in the urine assists in the formation of uric acid stones. Uric acid stones may also occur with high quantities of uric acid passed in the urine.

• Cystine Stones

These are very rare and usually an inherited disorder.

• Pain at the side or back 
• Blood in urine 
• Painful urination, cloudy urine or urine that smells bad 
• Fever usually suggests an associated infection

WHAT TESTS ARE USUALLY DONE TO CONFIRM THAT STONES ARE PRESENT?
A plain X ray of the urine tract called the KUB X-ray ( Kidney – Ureter – Bladder) can pick up about 85% of stones. These will be stones that contain calcium. Stones that do not contain calcium cannot be seen on a routine X-ray. Your doctor may order an IVU (intravenous urogram) instead which involves a dye being injected into the blood stream to “light up” the
whole urine tract as the dye gets excreted. This can also detect obstruction to urine flow, if present. A less informative but easier alternative is an ultrasound scan.

HOW TO FIND OUT WHAT TYPE OF STONES I HAVE?
The best way to find out what type of stones you have is to analyse the stone. If you know you are passing out a stone, you may catch it with a strainer and show it to your doctor. Other methods include a urine collection to look for abnormally high levels of the common constituents of stones. Blood tests may also be needed.

WHAT NEEDS TO BE DONE WHEN A KIDNEY STONE HAS BEEN DIAGNOSED?
Your doctor will need to:

a) Assess your kidney function to check if there has been any kidney damage

b) Decide on what to do with the stone that has already formed
Small stones which are causing no symptoms may be left alone. Small stones which are not obstructing and appear to be passing down the urine tract may be left alone to give it an opportunity to pass out on its own. However, if your doctor judges that it needs to be removed, he can choose one of the following options depending on the size, type and location of the stone. Each treatment has its advantages and disadvantages.

• Extracorporeal Shock Wave Lithotripsy (ESWL) is a non invasive method using shock waves
• Percutaneous lithotripsy with an endoscope inserted into the kidney with energy applied directly to the stone.
• Endoscopic lithotripsy for ureteral or bladder stones

Open surgery is now seldom done though it may still be necessary for large stones.

c) Discuss with you measures to preventing new stones from forming

These measures should be taken once a stone has been detected. They include:

• Keeping a high fluid intake 

This will prevent saturation of urine with substances which can form stones leading to crystallisation and eventual stone formation.

• Dietary restrictions

- Limiting sodium in the diet (to 2-3 g per day) to reduce urine calcium excretion
- Reduce a high calcium intake to a moderate calcium intake. A low calcium intake is not advisable because of the risk of osteoporosis (thin bones).
- Limiting the intake of coffee, tea, cola because they are rich in oxalate which can combine with calcium to ‘crystallise' and form stones
- You may be advised to eat less meat if you have uric acid stones

The assistance of a dietician is useful in assessing what is considered optimal for a patient.

POINTS TO REMEMBER
1) Untreated kidney stones can lead to kidney failure

2) See a doctor if you have:
- severe pain in your back or side that will not go away
- blood in the urine

3) Talk to your doctor about how to avoid more stones

4) Keep yourself well hydrated to prevent stone formation

What is Polycystic Kidney Disease?
Polycystic Kidney Disease (PKD) is an inherited form of kidney disease. This means that it is passed down from the biological parents to their children through abnormal genes. It was first described in the 19th century and many polycystic kidney disease families have been identified. There are 2 forms of this disease: the adult form which we will call Adult Polycystic Kidney Disease (APKD) and the rarer Infantile Polycystic Kidney Disease (IPKD).

APKD and IPKD are inherited differently – the APKD form is inherited in a dominant fashion i.e. if one parent has the defective gene in one of the two sets of 23 chromosomes and the gene is passed to his/her child the disease will manifest itself. Therefore, there is a 50% chance of the defective gene being passed on. This is entirely random and a parent can have 4 children and lucky enough to pass on only the set which contains the normal gene, so none of his children are affected. The disease may appear to skip a generation if the affected parent died young without showing some of the signs and symptoms.

In the early stage of the disease, many people do not know they are affected if they have no complaints and did not have an ultrasound scan performed. We now know that there are 3 types of genes involved in APKD (PKD1 on chromosome 16, PKD2 on chromosome 4 and PKD3 the location of which is unclear as yet). On the other hand, in the Infantile form (IPKD), the inheritance is recessive. It requires both parents to pass the defective gene to their child before the disease can manifest itself.

Adult Polycystic Kidney Disease (APKD) is the more common variety. Its incidence has been quoted to be about 1 in 1000 persons.

APKD affects the nephron. The nephron is the filtering unit of the kidneys and we have about 1 million of them in each kidney. The nephron comprises the filter (or glomerulus) and the tubule which drains the fluid that has been filtered into the ureter. The drained fluid is collected in the bladder to be passed out as urine.

In APKD, cysts form along the tubule. In time to come, compression of normal tissue and a scarring reaction occurs. The scarring reaction results from certain substances being secreted by the injured kidney. This process also involves a reduction of the blood supply in the very small vessels of the kidney further damaging the kidney.

The rate at which this occurs is different for every affected individual. Most of the affected people do not develop kidney failure until they are in their 40’s. Some may even be affected only in their 60’s or 70’s.

What are the symptoms and signs of the disease?

• Cysts in the kidneys
In the early stage there are no symptoms and the disease is usually picked up when ultrasound scanning is done for other reasons and cysts are noted in the kidneys. Health screening may pick up previously undetected high blood pressure or kidney failure.

• Enlarged Abdomen
As the cysts in the kidneys enlarge, patients may notice their abdomen getting bigger. The enlarging kidneys may cause some vague discomfort. There may be more severe pain if there is an infection involving the cysts or bleeding into the cysts. Infections of polycystic kidneys require more specific antibiotics than infections in normal kidneys because of the presence of cysts. The duration of treatment is also longer and usually last for several weeks.

• Blood in Urine
Bleeding from cyst ruptures may also cause episodes of passing urine with blood. This may be aggravated by trauma (physical injury) so patients should not engage in body-contact sports. Bleeding is usually self limiting. Only rarely does the kidney need to be removed because of persistent bleeding and severe blood loss.

• Hypertension
Many affected individuals develop hypertension. Uncontrolled hypertension can hasten the progression of kidney failure. It also has effects on the heart and is a risk factor in the development of heart failure, heart attack and stroke.

Are other organs affected in this disease?

Cysts can also develop in the liver as well as the pancreas. These do not usually cause problems.

Patients with APKD may have a higher incidence of:
• Aneurysms (outpouching of the blood vessels) in the brain which may rupture
• Prolapse mitral valve (abnormality of one of the heart valves)
• Colonic diverticulosis (outpouchings of the large intestine)
• Kidney stones

Can kidney failure be prevented?

• Blood pressure control
To delay the onset of kidney failure, very good blood pressure control is necessary. There are many blood pressure medications and your doctor will help you find a suitable one.

• Restriction of protein and salt intake
A restricted protein diet also helps to retard the progression of kidney failure. However, too strict a diet may cause malnutrition and this should be supervised by a dietician. Remember that restriction of salt is important in helping to maintain good blood pressure control.

What happens when the kidneys have totally failed?

As mentioned earlier, it may take many years before the kidneys totally fail. Dialysis will be needed to sustain life. If the patient is suitable for transplantation, kidney transplantation may be a better option. Before this happens, you should try to learn more about dialysis and transplantation from your doctor and other medical sources. A significant amount of preparation is required for a smooth transition to dialysis without the need for long periods of hospitalization. This is also important for people who are working so that there is minimal interruption to work.

Who should be tested for APKD?

All the direct blood relatives of an affected individual are at risk of having APKD and should be given advice regarding this illness. Because of the possibility of kidney failure and the effects of high blood pressure, they should be encouraged to go for screening. The most convenient and harmless method of screening for APKD is by ultrasound scanning. Most cysts will be evident by the time an individual is 30 years old.

Can women with APKD have children?

Patients with APKD can undergo normal pregnancies. There is increased risk if hypertension is already present or if kidney function is already abnormal.

Patients who are affected with APKD (both men and women) should consider the fact that each of their children has a 50% chance of the abnormal gene being passed to them. However, almost all children will live to adulthood.

If you have any further questions, you should approach your doctor who will be able to address your concerns.

You may visit these websites for more information:
http://www.davita.com
http://www.uptodate.com/patients/index.html

What is the urinary tract?

The urinary tract system consists of two kidneys, each with a draining ureter into the urinary bladder and the urethra through which urine is expelled from the body. Urine is produced by the kidneys as a filtrate from blood which has passed through the kidneys. Waste material and substances in excess is excreted into the urine by the kidney during the process of filtration and processing in the tubules and drained into the bladder through its ureter (see diagram). Urine is stored in the urinary bladder until it is passed out from the body through the urethra.

What is Urinary Tract Infection?

Urinary Tract Infection (UTI) refers to an infection in the urinary tract. It has been said that it is the next most common infection in women after the common ‘flu’. Under normal circumstances, the urinary tract is sterile or free from bacteria. Most of these infections are caused by germs (bacteria) existing in the intestinal tract and are passed out from the rectum through the anus. They stick to the skin around the genital areas. In an infection, these germs find their way up the urinary tract through the opening of the urethra. The most common bacteria is the Escherichia coli (E. Coli).

Some infections seem to be more severe than others.

Are there different types of UTI?

Severity usually depends on which part of the urinary tract is affected and whether the urinary tract is normal in structure. Infection can be classified into two types – uncomplicated and complicated.

1) Uncomplicated UTIs occur in persons without physiologic or anatomic abnormalities of the urinary tract and in the absence of recent urinary tract surgery. They are community acquired (outside of hospital) and can be divided into two groups depending on the localisation of the infection:
• Acute cystitis - lower urinary tract infection affecting the bladder
• Acute pyelonephritis - upper urinary tract infection affecting the kidney itself

2) Complicated UTIs occur in persons with obstruction, structure, or have disorders of the urinary tract that affect its function such as kidney failure.

Some conditions predispose one to getting an infection.
These include:
• Use of a urinary catheter (tube) that drains the bladder of urine when patients are unable to pass on their own. This can be left in place or inserted intermittently 6 to 8 times a day.
• Urinary instrumentation or surgery to the urine tract
• Incomplete voiding or urine left in the bladder from obstruction which may occur in elderly men with a large prostate, uterine prolapse in elderly ladies
• Presence of kidney stones
• Vesicoureteral reflux – the passage of urine from the bladder back into a ureter due to a developmental abnormality causing a faulty valve at the junction of the ureter with the bladder
• Pregnancy – because of physical changes that occur during pregnancy.
• Diabetics get more severe infections because of changes in the immune system

Who will get UTI?

It happens to both adults and children regardless of sex. Some people are more prone to getting a UTI than others.

It is more common:
• When the urinary tract is abnormal because of a developmental abnormality or
• With a disease process, urinary catheters (tubes) are used to drain urine or
• Persons who are critically ill or unconscious.

Do persons with normal urinary tract get UTI?

Certainly! Women with normal urine tract are up to 30 – 40 times more prone to getting UTI than men. This is due to the short length of the urethra in women, which allow bacteria easy access from the outside to enter the bladder. The urethral opening is also very close to the anus and vaginal areas where bacteria are present. Sexual activity in women also increases the risk of getting a UTI.

How will I know that I have an episode of UTI?

You may experience one or more of the following symptoms:
• Frequency, urgent need to urinate
• Burning sensation around the private parts when urinating
• Lower abdominal pain
• Milky or cloudy urine
• Unpleasant-smelling urine
• Blood or pus in the urine
• Lower back pain and
• Fever

Not all of these problems may be present at the same time.

Can UTI be prevented?

Episodes of UTI can be prevented by:
• Practicing good personal hygiene. This is especially important in women where the short urethra allows bacteria to travel into the bladder easily from the skin outside of the body.
• Drink plenty of water everyday (2 – 2.5 L/day). The urine produced can flush the urethra of the bacteria.
• Take showers instead of soaking in the bathtub
• Urinate when you feel the need, avoid overstretching the bladder

For females:
• After micturation or a bowel motion where washing is not possible, wipe from front (the “clean area”) to the back (the “less clean area”) after urination to prevent bacteria around the anus from entering the vagina or urethra.
• Make sure both partners wash the perineal area before and after sex to reduce the numbers of bacteria present on the skin around the area.

How do I confirm that I have UTI?

Confirmation is done through urine tests performed to look for the presence of white blood cells. The white blood cells increase with the amount of inflammation. These can be detected using dipstick reagent strips or by looking at the urine through a microscope and the amount of white blood cells counted. Often red blood cells are also present. The urine can also be cultured for bacterial growth and tested against a range of antibiotics to assist the doctor in the choice of antibiotic should the initial treatment be unsuccessful. However, culture is not useful once antibiotics have been started, as the bacteria often would not grow in the presence of antibiotics.

In order to have an accurate diagnosis, the method of collecting urine specimen is very important. This is because contamination can occur from the skin surface as well as vaginal secretions in the female and smegma in the male. The cells seen on microscopy may be coming from contaminants rather than the urine itself. The nurse in the clinic will instruct you on how to collect a midstream urine specimen to avoid this problem. It is important to follow these instructions to avoid getting a contaminated sample.

Since there may be other causes leading to UTI, are investigations performed to look for a cause in every case of UTI?

Not all cases of UTI are investigated. Your doctor will decide if further tests are required. Some of the tests may include:

• Intravenous urogram (IVU)
In this test, an opaque dye is injected into a vein to give X-ray images of the bladder, kidneys and ureters to look for abnormalities in the urine tract

• Cystoscopy
An instrument that allows the doctor to see the inside of the bladder from the urethra

• Ultrasound examination
This examination is performed using sound waves to look for obstruction in the urine tract.

How is UTI treated?

Treatment includes antibiotics to get rid of bacteria. This may take a few days. In the meantime pain relievers can be taken at the same time. Drinking plenty of water will also help to flush bacteria as well as diluting the amount of bacteria.

It is important to complete the course of antibiotics as the UTI may recur if the bacteria are not destroyed completely. More importantly, the bacteria that initially caused the infection would become resistant to the antibiotic previously used and a new course with another antibiotic would have to be started.

I get recurrent UTI, what can be done about this?

Recurrent UTI should be investigated to search for an underlying cause so that it can be eradicated or corrected.
For those females who have normal urine tracts, a course of preventive antibiotics can be prescribed.

Can UTI lead to kidney failure?

Fortunately, with prompt treatment UTI is quite unlikely to lead to kidney failure. However, if a person has urinary tract obstruction, reflux or some other urinary abnormalities, infection may lead to progressive damage of the kidneys.

Always remember two most important things to do to prevent further infections:
• Practice good hygiene
• Drink plenty of water

You may visit these websites for more information:
http://www.davita.com
http://www.uptodate.com/patients/index.html