What happens when your kidneys fail?

Healthy kidneys clean the blood by filtering out extra water and wastes.

They also make hormones that keep your bones strong and blood healthy.

When both of your kidneys fail, your body holds fluid. Your blood pressure rises. Harmful wastes build up in your body. Your body doesn't make enough red blood cells. You develop fatigue, nausea, and loss of appetite.When this happens, you need treatment to replace the work of your failed kidneys.

Kidney failure

Various conditions can damage your kidneys, including both primary kidney diseases and other conditions that affect the kidneys.

•     If kidney damage becomes too severe, your kidneys lose their ability to function normally. This is called kidney failure.
•     Kidney failure can happen rapidly (acute kidney failure), usually in response to a severe acute (sudden, short-term) illness in another body system or in the kidneys. It is often completely reversible with resolution of the underlying condition.
•     Kidney failure can also happen very slowly and gradually (chronic kidney failure), usually in response to a chronic (ongoing, long-term) disease such as diabetes or high blood pressure.
•     Both types of kidney failure can occur in response to primary kidney disease as well. In some cases this kidney disease is hereditary.
•     Infections and substances such as drugs and toxins can permanently scar the kidneys and lead to their failure.

How the kidneys work

The kidneys have several important functions in the body.

•    They filter wastes from your bloodstream and maintain the balance of electrolytes in your body.
•    They remove chemical and drug by-products and toxins from your blood.
•    They eliminate these substances and excess water as urine.
•    They secrete hormones that regulate the absorption of calcium from your food (and thus bone strength), the production of red blood cells (thus preventing anemia), and the amount of fluid in your circulatory system (and thus blood pressure).

When blood enters the kidneys, it is first filtered through structures called glomeruli. The second step is filtering through a series of tubules called nephrons.

•    The tubules both remove unwanted substances and reabsorb useful substances back into the blood.
•    Each of your kidneys contains several million nephrons, which cannot be restored if they are damaged.

What are the treatments for kidney failure?

There are three options when treating kidney failure, which will be discussed in length in the following sections:

1. Hemodialysis
2. Peritoneal dialysis
3. Kidney transplant

How does hemodialysis work?

Hemodialysis uses a dialyzer, or special filter, to clean your blood. The dialyzer connects to a machine. During treatment, your blood travels through tubes into the dialyzer. The dialyzer filters out wastes and extra fluids. Then the newly cleaned blood flows through another set of tubes and back into your body.

What is peritoneal dialysis?

Peritoneal dialysis is another procedure that replaces the work of your kidneys. It removes extra water, wastes, and chemicals from your body. This type of dialysis uses the lining of your abdomen to filter your blood. This lining is called the peritoneal membrane.

Kidney Transplantation

When your health care provider makes the diagnosis of end-stage renal disease, he or she will discuss your treatment options. Whether kidney transplantation is an option for you depends on your specific situation. If your health care provider thinks you may be eligible for a transplant, you will learn about the pros and cons of this treatment. If you are a potential candidate, you will undergo a thorough medical evaluation. In the meantime, you will be treated with dialysis.

Kidney transplantation is replacement of nonworking kidneys with a healthy kidney from another person (the donor). The healthy kidney (the "graft") takes over the functions of your nonworking kidneys. You can live normally with only one kidney as long as it functions properly.

The transplantation itself is a surgical operation. The surgeon places the new kidney in your abdomen and attaches it to the artery that supplied blood to one of your kidneys and to the vein that carries blood away from the kidney. The kidney is also attached to the ureter, which carries urine from the kidney to the bladder. Your own kidneys are usually left in place unless they are causing you problems, such as infection.

Every operation has risks, but kidney transplantation is not a particularly difficult or complicated operation. It is the period after the surgery that is most critical. Your medical team will watch very carefully to make sure that your new kidney is functioning properly and that your body is not rejecting the kidney.

Kidney Failure Symptoms

The symptoms of kidney failure vary widely by cause of the kidney failure, severity of the condition, and the other body systems that are affected.

* Most people have no symptoms at all in the early stages of the disease, because the kidneys are able to compensate so well for the early impairments in the their function. Others have symptoms that are mild, subtle, or vague.
* Generally, obvious symptoms appear only when the condition has become severe or even critical.
* Kidney failure is not painful, even when severe, although there may be pain from damage to other systems.
* Some types of kidney failure cause fluid retention. However, severe dehydration (fluid deficiency) can also cause kidney failure.
* Fluid retention - Puffiness, swelling of arms and legs, shortness of breath (due to fluid collection in the lungs, called pulmonary edema)
* Dehydration - Thirst, rapid heart rate (tachycardia), dry mucous membranes (such as inside the mouth and nose), feeling weak or lethargic

Other common symptoms of kidney failure and end-stage renal disease include the following:

* Urinating less than usual
* Urinary problems - Frequency, urgency
* Bleeding - Due to impaired clotting, from any site
* Easy bruising
* Fatigue
* Confusion
* Nausea, vomiting
* Loss of appetite
* Pain - In the muscles, joints, flanks, chest
* Bone pain or fractures
* Itching 
* Pale skin (from anemia)

What is a kidney stone?

A kidney stone can develop when certain chemicals in your urine form crystals that stick together. The crystals may grow into a stone ranging in size from a grain of sand to a golf ball. Most stones form in the kidneys. Very small stones can pass through the urinary system without causing problems. However, larger stones, when traveling from the kidney through the ureter to the bladder, can cause severe pain called colic.

Most stones (70 to 80 percent) are made of calcium oxalate. A smaller number are made of uric acid or cystine.

Who is affected by kidney stones?

One out of ten Canadians will have a kidney stone at some point in their life. Kidney stones occur much more commonly in men than in women. They tend to affect people in middle age, and occur more frequently hot climates.

What causes kidney stones to form?

Normally, urine contains chemicals which prevent crystals from forming. However, some people seem to be more prone to kidney stones than others.

If you are prone to kidney stones, there are several factors which contribute to their formation:

* Consuming too much calcium oxalate or food high in uric acid in your diet
* Drinking too little fluid
* Blockage of the urinary tract
* Certain metabolic diseases
* Recurrent urinary tract infections
* Consuming too much Vitamin C or D
* Bed rest for several weeks or more
* Certain medications

Sometimes, no causes can be found.

What are the symptoms of kidney stones?

* Severe pain that usually starts suddenly in the small of the back under the ribs or in the lower abdomen, and which may move to the groin; the pain may last for minutes or hours, followed by periods of relief.
* Blood in the urine
* Nausea and vomiting

If you have a urinary tract infection, you may also experience:

* Burning during urination and the urge to urinate frequently
* Cloudy or foul-smelling urine
* Fever, chills and weakness

How are kidney stones diagnosed?

Kidney stones are diagnosed by a complete medical examination, X-rays and other tests. You will first be given a physical examination and asked questions about past kidney illness, your diet, use of medications, your lifestyle and family background. Your doctor will then perform a urine test to see if there is blood in the urine, and a blood test to check your kidney function and whether you have any metabolic abnormalities; an ultrasound, X-ray or a CT scan will also be scheduled.

An X-ray of the kidneys, ureters and bladder can reveal the presence of most stones. Sometimes, stones which are less common can be seen using an intravenous injection of dye or an ultrasound test.

How are kidney stones treated?

Most small stones pass through your body by themselves within hours or a few days. To help this process, your doctor will prescribe painkillers and advise you to drink lots of fluids and follow a special diet.

Stones that do not pass by themselves may have to be removed if they are stuck in the lower part of the ureter, or crushed with Extra-corporeal Shock Wave Lithotripsy (ESWL). This treatment is a non-surgical technique that uses high-energy shock waves to break the stones into small fragments (about the size of grains of sand). You can then pass them when you urinate during the next few weeks. This treatment is successfully used in many cases where the stones are less than two centimetres in size. When stones are larger than two centimetres, a surgical procedure is often needed.

The stones that you pass at home and those that are surgically removed should be sent to a laboratory for analysis.

Certain types of stones can be dissolved using medication. However, the most common stones (those containing calcium) can not be dissolved.

How can you help prevent the formation of kidney stones?

There are steps you can take, in consultation with your doctor and dietitian, to help prevent kidney stones.
* Drink at least two litres of water during the day and a glass of water whenever you get up at night to pass urine. Be sure to drink plenty after meals and after exercise.
* If you have calcium oxalate stones, be sure to stay within the recommended dietary allowance for calcium and avoid foods high in oxalate content (such as tea or chocolate). Do not take very large doses of Vitamin C (4 grams or more daily) and avoid heavy use of antacids. Vitamin B6 (not exceeding 50 mg/day) may protect against recurrent calcium oxalate stones.
* Decrease protein and salt intake.
* If you have uric acid stones, cut down on the amount of red meat you eat.