Chronic renal failure, or chronic kidney disease (CKD), is a slow and progressive decline of kidney function. It's usually a result of a complication from another serious medical condition such as diabetes, high blood pressure or cardiovascular disease. Unlike acute renal failure, which happens quickly and suddenly, chronic renal failure happens gradually – over a period of weeks, months, or years – as the kidneys slowly stop working, leading to end-stage renal disease (ESRD).
The progression is so slow that symptoms usually don't appear until major damage is done. In Canada, approximately 1 in every 10 Canadians has chronic kidney disease.
The kidneys play three major roles:
- removing waste products from the body, keeping toxins from building up in the bloodstream
- producing hormones that control other body functions, such as regulating blood pressure and producing red blood cells
- regulating the levels of minerals or electrolytes (e.g., sodium, calcium, and potassium) and fluid in the body
Most people have two functioning kidneys. It's entirely possible to live a full, healthy life with only one kidney – one fully functioning kidney can do the work of two – but it's essential to watch for signs of any problems with the remaining kidney.
When kidneys get to the point where they can't function at all, kidney dialysis or a transplant is the only way to remove the body's waste products.
The most common causes of chronic renal failure in North America are diabetes mellitus (type 1 or type 2 diabetes) and high blood pressure.
One of the complications resulting from diabetes or high blood pressure is the damage to the small blood vessels in the body. The blood vessels in the kidneys also become damaged, resulting in CKD.
Other common causes of chronic renal failure include:
- recurring pyelonephritis (kidney infection)
- polycystic kidney disease (multiple cysts in the kidneys)
- autoimmune disorders such as systemic lupus erythematosus
- hardening of the arteries, which can damage blood vessels in the kidney
- urinary tract blockages and reflux, due to frequent infections, stones, or an anatomical abnormality that happened at birth
- excessive use of medications that are metabolized through the kidneys
- increased urination, especially at night
- foamy or bubbly urine (indicates proteins are present in the urine)
- urine that is cloudy or tea-coloured
- puffy eyes, hands, and feet (called edema)
- high blood pressure
- shortness of breath
- loss of appetite
- nausea and vomiting (this is a common symptom)
- bad taste in the mouth or bad breath
- weight loss
- generalized, persistent itchy skin
- muscle twitching or cramping
- a yellowish-brown tint to the skin
- high blood pressure (hypertension)
- increased risk of bleeding
- increased risk of infection
- fluid overload (called edema)
- electrolyte abnormalities (e.g., hyperkalemia, high levels of potassium in the blood)
- mineral abnormalities (e.g., hypercalcemia [high levels of calcium in the blood] or hyperphosphatemia [high levels of phosphorus in the blood])
- brittle bones
- blood pressure (many people with chronic renal failure have high blood pressure)
- urine tests (to detect proteinuria – excess protein in the urine)
- blood tests
- X-rays of the kidneys
- abdominal CT or CAT (computed tomography) scan
- abdominal MRI (magnetic resonance imaging)
- abdominal ultrasound
- renal scan
- manage cardiovascular disease risk factors such as:
- avoid smoking –smoking can speed up damage to the small blood vessels in the body
- monitor blood pressure regularly and ask what your target blood pressure should be
- maintain a healthy weight with a healthy diet and get regular exercise
- limit alcohol intake
- follow recommended treatments for chronic diseases such as diabetes, lupus, and hypertension
- don't misuse prescription or over-the-counter medications – ask the pharmacist which medications are safe to use and won't cause further damage to the kidneys
- get treatment for urinary tract infections or any type of urinary problems as soon as possible
Symptoms and Complications
Chronic renal failure can be present for many years before you notice any symptoms. When you first start losing kidney function, the healthy tissues in the kidney will help to compensate for the loss by working harder. If your doctor suspects that you may be likely to develop renal failure, they will probably catch it early by conducting regular blood and urine tests. If regular monitoring isn't done, the symptoms may not be detected until the kidneys have already been damaged. Some of the symptoms – such as fatigue – may have been present for some time, but can come on so gradually that they aren't noticed or attributed to kidney failure.
Some signs of chronic renal failure are more obvious than others. These are:
Other symptoms aren't as obvious, but are a direct result of the kidneys' inability to eliminate waste and excess fluid from the body:
As the kidney failure gets worse and the toxins continue to build up in the body, seizures and mental confusion can result.
Being diagnosed with chronic renal failure can be very frightening. The future of the condition, however, depends on the medical problem that caused the kidney failure, how much kidney damage has occurred, and what, if any, complications are present.
Some of these complications may include:
Making the Diagnosis
Your medical history is important in determining your risk factors for developing kidney failure. After taking a thorough history, your doctor will check any or all of the following:
The X-rays, scans, and ultrasounds check for abnormalities in the kidneys, such as small size, tumours, or blockages. These various tests will allow the doctor to recognize if any abnormal kidney function is present and to diagnose CKD.
Treatment and Prevention
Initially, people with kidney failure are usually advised to make changes to their diet. A low-protein diet is often recommended to help slow down the buildup of waste in the body and to help limit the nausea and vomiting that can accompany chronic renal failure. A qualified dietitian can help determine the proper diet. The underlying illness or illnesses need to be considered when making any diet changes.
Because the kidneys aren't eliminating body waste as effectively as they should, the levels of electrolytes (sodium and potassium) and minerals (calcium and phosphate) in your body may either rise too high (most common) or be eliminated too quickly. These electrolytes and minerals are measured through regular blood tests, and if the levels are not in balance, diet or medication changes may be recommended. Many people with CKD have to restrict salt intake.Your doctor may also check your levels of vitamin D in your blood, since this can be lower in people with kidney disease. Your doctor may suggest taking supplements or medications to help manage the imbalance.
If the kidneys aren't allowing the body to get rid of the excess fluid, fluid intake may need to be restricted. This is so that the kidneys and heart don't have to work as hard. The amount of fluid allowed can be determined ahead of time, but often a day's allotment is based on the amount of urine put out the day before. For example, someone who puts out 500 mL of urine in one day might be allowed to drink 500 mL of fluid over the following 24 hours, and so on. Fluid restrictions are usually only used in severe cases of swelling or if the renal failure has progressed to end-stage renal failure and dialysis has become necessary. Dietitians can help arrange diets around fluid restrictions, and teach what is allowed and what should be avoided.
If, despite treatment, the kidneys continue to get worse, dialysis or a kidney transplant becomes necessary.
There are two types of dialysis: peritoneal dialysis and hemodialysis. Dialysis is a process that removes excess fluids and waste using a membrane instead of a kidney as the filter. The type of dialysis depends on many factors including a person's lifestyle. Dialysis isn't a cure, and people who are on dialysis still must follow special diets, reduce their fluids, and take medications as prescribed by their doctors.
Peritoneal dialysis uses the natural membrane of the abdominal cavity as its filter. It can only be used by people who have not had major abdominal surgery. Using a catheter (a very small, flexible tube) that's been permanently placed into the abdomen, the abdominal cavity is filled with a solution called dialysate, which stays there for a set amount of time. The dialysate draws the waste and extra fluid out of the bloodstream through the membrane. When finished, the dialysate – now with the extra body fluid and waste mixed in – is drained out and then replaced with fresh dialysate. Usually done at home, this procedure is continuous and done in cycles. Peritoneal dialysis can be performed by one's self or by a family member. It's done daily, but the frequency of cycles during the day varies according to the type of peritoneal dialysis being done. The cycles can occur as often as every few hours, or the procedure can span the night with the use of a cycling machine that exchanges the fluid automatically while the person sleeps.
Peritoneal dialysis doesn't work for everyone and may eventually stop working effectively for those who do use it. If this happens, hemodialysis is necessary.
Hemodialysis is a procedure that must be done in a hospital or special clinic setting. With hemodialysis, the waste and excess body fluid is filtered out through the blood using a dialyser, a coiled membrane made up of hundreds of hollow fibers A dialysis machine pumps the blood through the dialyser. The blood stays on one side of the membrane, while the dialysate is on the other side of the membrane. As with the peritoneal dialysis, the dialysate draws the extra body fluid and waste through the filter and then the filtered blood is pumped back into the body. The process of hemodialysis is quicker than peritoneal dialysis, and the cycle is generally complete in four to five hours. It's usually done about three times a week.
Chronic renal failure often causes anemia, a condition where there are not enough healthy red blood cells in the body. For some people with anemia caused by chronic renal failure, their doctor may advise them to take medications that treat anemia by stimulating the body to produce more red blood cells.
A kidney transplant is a solution for some people with chronic renal failure. At some point, everyone with the condition is assessed for a kidney transplant. However, some who have other serious conditions may be at an increased risk of complications from surgery or antirejection medications so a transplant may not be a suitable option for them. A kidney can be transplanted from a living donor (often a relative) or a donor who has recently died and left their organs for donation. With a successful transplant and proper medical care, a kidney recipient can go on to lead a healthy life for many years.
Prevention of chronic renal failure must begin long before any signs of kidney failure are noticed. Many people with CKD already have or will develop cardiovascular disease. Because chronic renal failure and cardiovascular disease share some of the same risk factors, for example, diabetes and high blood pressure, it becomes important to manage these risk factors of cardiovascular disease to effectively manage CKD. This involves maintaining good blood pressure and cholesterol control, as well as keeping blood sugar levels under control if you have diabetes. Doctors may also suggest making certain lifestyle changes, such as quitting smoking, maintaining a healthy diet (e.g., reducing salt intake), and exercising regularly.
People who are at high risk of developing chronic renal failure should be aware of the potential risks. They should also be taught how to take steps to avoid the onset of kidney failure and how to recognize some of the warning signs. While there's no cure, there are steps that can be taken to reduce the complications and symptoms.
Some ways to prevent or slow down the onset of chronic renal failure are:
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