What Is Chronic Kidney Failure? What Causes Chronic Kidney Disease?

What Is Chronic Kidney Failure? What Causes Chronic Kidney Disease?
25 Nov 2009

Chronic kidney failure, also known as chronic renal failure, chronic renal disease, or chronic kidney disease, is a slow progressive loss of kidney function over a period of several years. Eventually the patient has permanent kidney failure. Chronic kidney failure is much more common than people realize, and often goes undetected and undiagnosed until the disease is well advanced and kidney failure is fairly imminent. It is not unusual for people to realize they have chronic kidney failure only when their kidney function is down to 25% of normal.

As kidney failure advances and the organ's function is seriously impaired, dangerous levels of waste and fluid can rapidly build up in the body. Treatment is aimed at stopping or slowing down the progression of the disease - this is usually done by controlling its underlying cause.

If chronic kidney failure ends in end-stage kidney disease, the patient will not survive without dialysis (artificial filtering) or a kidney transplant.

According to the NHS (National Health Service), UK, approximately 1 to 4 in every 1,000 British people are affected by chronic kidney disease. The average age of a British person with the disease is 77. In the UK, health authorities report that people of South Asian, African and Afro-Caribbean descent are at a higher risk of developing the disease, compared to other people.

According to Medilexicon's medical dictionary:

Renal failure is "loss of renal function, either acute or chronic, that results in azotemia and syndrome of uremia. (Synonym: End Stage Renal Disease, ESRD)"

What are the risk factors of chronic kidney failure?
A risk factor is a condition, situation or environment which raises the risk of developing a disease or condition. For example, obese people have a higher risk of developing Diabetes Type II. Therefore, obesity is a risk factor for Diabetes Type II.

The following conditions or situations are linked to a higher risk of developing kidney failure:

* A family history of kidney disease
* Age - chronic kidney disease is much more common among people over 60 years of age
* Atherosclerosis
* Bladder obstruction
* Chronic glomerulonephritis
* Congenital kidney disease (kidney disease which is present at birth)
* Diabetes - the most common risk factor in Europe, Japan, North America, and probably most other parts of the world.
* Hypertension (high blood pressure)
* Lupus erythematosis
* Overexposure to some toxins
* Sickle cell disease
* Some medications

What are the signs and symptoms of chronic kidney failure?
A symptom is something the patient feels and reports, while a sign is something other people, including a doctor or a nurse may detect. For example, pain may be a symptom while a rash may be a sign.

Chronic kidney failure, as opposed to acute kidney failure, is a slow and gradually progressive disease. Even if one kidney stops functioning, the other can carry out normal functions. It is not usually until the disease is fairly well advanced and the condition has become severe that signs and symptoms are noticeable; by which time most of the damage is irreversible.

It is important that people who are at high risk of developing kidney disease have their kidney functions regularly checked. Early detection can significantly help prevent serious kidney damage.

The most common signs and symptoms of chronic kidney disease include:

* Anemia
* Blood in urine
* Dark urine
* Decreased mental alertness
* Decreased urine output
* Edema - swollen feet, hands and ankles
* Fatigue (tiredness)
* Hypertension (high blood pressure)
* Insomnia
* Itchy skin, can become persistent
* Loss of appetite
* Male inability to get or maintain an erection (erectile dysfunction)
* More frequent urination, especially at night
* Muscle cramps
* Muscle twitches
* Nausea
* Pain on the side or mid to lower back
* Panting (shortness of breath)
* Protein in urine
* Sudden change in bodyweight
* Unexplained headaches

What are the causes of chronic kidney failure?
Our kidneys carry out the complex system of filtration in our bodies - excess waste and fluid material are removed from the blood and excreted from the body. Our kidneys get their blood and oxygen supply from the renal arteries, which are branches of the abdominal aorta (another artery). When it enters the kidneys, blood goes through smaller and smaller blood vessels - the smallest ones being the glomeruli (tiny capillary blood vessels which are arranged in tufts).

It is in the glomeruli that blood is filtered - waste, fluids and other substances are extracted and cross into miniscule tubules, from which the bloodstream reabsorbs what the body is able to reuse. What the body cannot reuse - waste - is excreted in our urine.

In most cases our kidneys are able to eliminate all waste materials that our body produces. However, if the blood flow to the kidneys is affected, of the tubules or glomeruli are not working properly because of damage or disease, or if urine outflow is obstructed, problems can occur.

In the majority of cases progressive kidney damage is the result of a chronic disease (a long-term disease), such as:

* Diabetes - chronic kidney failure is linked to both Diabetes Types I and II. If the patient's diabetes is not well controlled, excess sugar (glucose) can accumulate in the blood. Glucose can damage the glomeruli.

The risk of chronic kidney failure is higher among patients with Diabetes Type I. Doctors say that approximately 20% to 40% of patients with Diabetes Type I develop kidney disease by the time they are 50 years of age.

Kidney disease is not common during the first ten years of diabetes; it more commonly occurs between years 15 to 25 after diagnosis (of diabetes). However, as treatment methods improve, experts say that the number of diabetes patients developing kidney disease is falling.

* Hypertension (high blood pressure) - high blood pressure can damage the glomeruli.

* Obstructed urine flow - if urine flow is obstructed it can back up into the kidney from the bladder (vesicoureteral reflux). Blocked urine flow increases pressure on the kidneys, and undermines their function. Possible causes include an enlarged prostate, kidney stones, or a tumor.

* Kidney diseases - including polycystic kidney disease, pyelonephritis, or glomerulonephritis.

* Kidney artery stenosis - the renal artery narrows or is blocked before it enters the kidney.

* Certain toxins - including fuels, solvents (such as carbon tetrachloride), and lead (and lead-based paint, pipes, and soldering materials). Even some types of jewelry have toxins which can lead to chronic kidney failure.

* Fetal developmental problem - if the kidneys do not develop properly in the unborn baby while it is developing in the womb.

* Systemic lupus erythematosis - an autoimmune disease. The body's own immune system attacks the kidneys as though they were foreign tissue.

* Malaria and yellow fever

* Some medications - overuse of, for example, NSAIDs (non-steroidal anti-inflammatory drugs), such as aspirin or ibuprofen.

* Illegal drug abuse - such as heroin or cocaine.

* Injury - a sharp blow or physical injury to the kidney(s)

How is chronic kidney failure diagnosed?
A doctor will check for signs and ask the patient about symptoms. The following tests may also be ordered:

Blood test - to determine whether waste substances are being adequately filtered out. If levels of urea and creatinine are persistently high, the doctor will most likely diagnose end-stage kidney disease.

Urine test - to find out whether there is either blood and/or protein in the urine.

Kidney scans - this may include a magnetic resonance imaging (MRI) scan, computed tomography (CT) scan, or an ultrasound scan. The aim is to determine whether there are any blockages in the urine flow. These scans can also reveal the size and shape of the kidneys - in advanced stages of kidney disease the kidneys are smaller and have an uneven shape.

Kidney biopsy - a small sample of kidney tissue is extracted and examined for cell damage. An analysis of kidney tissue makes it easier to make a specific diagnosis of kidney disease.

Chest X-ray - the aim here is to check for pulmonary edema (fluid retained in the lungs).

Glomerular filtration rate (GFR) and kidney disease stages

GFR is a test that measures the glomerular filtration rate - it compares the levels of waste products in the patient's blood and his/her urine. GFR measures how many milliliters (ml) of waste the kidneys are able to filter per minute. The kidneys of healthy individuals can typically filter over 90 ml per minute.

Changes in the GFR rate can assess how advanced the kidney disease is. In the UK, and many other countries, kidney disease stages are classified as follows:

* Stage 1 - GFR rate is normal. However, evidence of kidney disease has been detected.
* Stage 2 - GFR rate is lower than 90 ml, and evidence of kidney disease has been detected.
* Stage 3 - GFR rate is lower than 60 ml, regardless of whether evidence of kidney disease has been detected.
* Stage 4 - GRF rate is lower than 30 ml, regardless of whether evidence of kidney disease has been detected.
* Stage 5 - GFR rate is lower than 15 ml. Renal failure has occurred.

The majority of patients with chronic kidney failure rarely progress beyond Stage 2. If the patient does not feel symptoms until Stage 4, any kidney damage is irreversible.

It is important for kidney disease to be diagnosed and treated early for serious damage to be prevented.

Patients with diabetes - a diabetes patient should have an annual test which measures microalbuminuria (small amounts of protein) in urine. This test can detect early diabetic nephropathy (early kidney damage linked to diabetes).
What is the treatment for chronic kidney failure?
There is no current cure for chronic kidney failure. However, there are therapies that can help control the signs and symptoms, reduce the risk of complications, and slow the progression of the disease. A GP (general practitioner, primary care physician) will refer a patient with suspected kidney failure to a nephrologist (a kidney specialist).

Patients with chronic kidney failure typically need to take a large number of medications.

* Anemia treatment - hemoglobin is the substance in red blood cells that carries vital oxygen around the body. If hemoglobin levels are low the patient has anemia.

Some kidney disease patients with anemia will require blood transfusions - the blood is injected into a vein, usually in a hospital.

As iron is required for the production of red blood cells, a patient with kidney disease will usually have to take iron supplements, either in the form of daily ferrous sulphate tablets, or occasionally in the form of injections.

If the anemia is not effectively treated with transfusion or iron supplements, the patient may receive an injection of erythropoietin. Erythropoietin is a hormone our body needs for the production of red blood cells. Epoetin may be given once a week, or Darbepoeitin may be given three times a week.

* Treatment for phosphate balance - people with kidney disease may not be able to eliminate phosphate from their body properly. Patients will be advised to reduce their nutritional phosphate intake - this usually means reducing their consumption of dairy products, red meat, eggs and fish.

If diet does not solve the problem the patient may be given a phosphate binder. This medication binds to the phosphate in the food in the stomach, preventing the body from absorbing it. Examples include Adcal, Calcichew, Alucaps and Sevelamer. These medicines are taken with meals.

* Vitamin D - patients with kidney disease typically have low levels of vitamin D. Vitamin D is essential for healthy bones. The vitamin D we obtain from the sun or from food has to be activated by the kidneys before it can be used by the body. Patients may be given alfacalcidol, or calcitriol.

* High blood pressure (hypertension) - high blood pressure is a common problem for patients with chronic kidney failure. It is important to bring the blood pressure down to protect the kidneys, and subsequently slow down the progression of the disease. Most commonly, the patient will be prescribed ACE (angiotensin converting enzyme) inhibitors. Examples include captopril, enalapril, lisinopril, perindopril, and ramipril. Other medicines are available if these don't work.

* Edema (fluid retention) - people with chronic kidney failure need to be careful with their fluid intake. Most patients will be asked to restrict their fluid intake. If the kidneys do not work properly the patient is much more susceptible to fluid build-up.

The doctor may also prescribe diuretics, such as furosemide, which help the body eliminate excess fluid.

* Skin itching - antihistamines, such as chlorphenamine, may help alleviate symptoms of itching.

* Anti-sickness medications (antiemetics) - if toxins build up in the body because the kidneys don't work properly, patients may feel sick (nausea). Medications such as cyclizine, or metaclopramide help relieve sickness.

* Diet - following a proper diet is vital for effective kidney failure treatment. As mentioned above, restricting the amount of protein in the diet may help slow down the progression of the disease. Diet may also help alleviate symptoms of nausea. Salt intake needs to be carefully regulated to control hypertension. Potassium and phosphorus consumption, over time, may also need to be restricted.

* NSAIDs (nonsteroidal anti-inflammatory drugs) - such as aspirin or ibuprofen should be avoided and only taken if the doctor says so.

End-stage kidney disease treatment
This is when the kidneys are functioning at less than 10% - 15% of normal capacity. Measures used so far - diet, medications and treatments controlling underlying causes - are no longer enough. The kidneys of a patient with end-stage kidney disease cannot keep up with the waste and fluid elimination process on their own - the patient will need dialysis or a kidney transplant in order to survive.

Most doctors will try to delay the need for dialysis or a kidney transplant for as long as possible because they have risks of potentially serious complications.

Kidney dialysis - this is the removal of waste products and excessive fluids from blood when the kidneys cannot properly do the job any more. Dialysis has some serious risks, including infection. However, it can also help the patient survive for considerably longer (than without it).

There are two main types of kidney dialysis. Each type also has subtypes. The two main types are:

* Hemodialysis - blood is pumped out of the patient's body and goes through a dialyzer (an artificial kidney). The blood is pumped out through two routes: 1. A catheter is placed in one of the main blood veins, or 2. A surgically created junction between a vein and artery in the patient's arm.

The blood moves across membranes in the dialyzer that filter out waste. The blood is then returned to the patient's body. At any one time, just 237 milliliters (one cup) of blood is outside the body.

The patient undergoes hemodialysis about three times per week. Each session lasts for at least three hours. Experts now recognize that more frequent sessions result in a better quality of life for the patient, as well as a better control of complications and lower risk of death. Modern home-use dialysis machines are making this more regular use of hemodialysis more feasible today.

* Peritoneal dialysis - the blood is filtered in the patient's own abdomen; in the peritoneal cavity which contains a vast network of tiny blood vessels. A catheter is implanted into the abdomen, into which a dialysis solution is infused and drained out for as long as is necessary to remove waste and excess fluid.

o Continuous ambulatory peritoneal dialysis - the dialysis solution is exchanged in the abdomen four times a day, every day. Sessions are equally spaced throughout the day. The patient carries out the procedure himself/herself.

o Continuous cycling peritoneal dialysis - a cycler machine automatically infuses daily solution into the peritoneal cavity and takes it out while the patient is sleeping.

Kidney transplant

Kidney transplant is a better option than dialysis for patients who have no other conditions apart from kidney failure. Even so, candidates for kidney transplant will have to undergo dialysis until they receive a new kidney.

The kidney donor and recipient should have the same blood type, cell-surface proteins and antibodies, in order to minimize the risk of rejection of the new kidney. Siblings or very close relatives are usually the best types of donors. If a living donor is not possible, the search will begin for a cadaver donor (dead person).
What are the possible complications of chronic kidney failure?
If the chronic kidney disease progresses to kidney failure, the following complications are possible:

* Anemia - hemoglobin levels drop and not enough oxygen reaches many parts of the body.
* Central nervous system damage.
* Dry skin, skin color changes.
* Fluid retention - this can lead to swollen tissue, heart failure, and fluid build-up in the lungs.
* Hyperkalemia - blood potassium levels rise; this can result in heart damage.
* Insomnia - this is a common consequence of kidney failure
* Lower libido (sex drive)
* Male erectile dysfunction.
* Ostemalacia - bones become weak and break easily.
* Pecarditis - the sac-like membrane that envelops the heart (pericardium) becomes inflamed.
* Stomach ulcers.
* Weak immune system - the patient becomes much more susceptible to infection.

Complications in children

* Erythropoietin production drops, resulting in a much lower red blood cell count.
* Vitamin D - the kidneys will no longer be able to activate vitamin D, resulting in poor calcium absorption and muscle function.

Consequently, children with kidney failure may fail to grow properly.

Complications during pregnancy

When a woman is pregnant the kidneys have to work especially hard because the amount of fluid in the body increases. Pregnant women with chronic kidney failure may experience worsening hypertension and an increase in waste products in their blood. This can affect both the mother and her baby. Hypertension means the baby will get loss blood through the placenta, resulting in possible growth problems. Waste products in the bloodstream may also affect the baby.

Women with chronic kidney failure who are pregnant have a significantly higher risk of developing preeclampsia, compared to other women - blood pressure rises dangerously high. If left untreated the result could be a brain hemorrhage, or hemorrhaging in the liver or kidneys - both potentially fatal for both mother and baby.
Prevention of chronic kidney failure
Managing the chronic condition - people who have a chronic condition, such as diabetes, which are closely linked to chronic kidney failure risk, can significantly reduce their chances of developing kidney failure if they control their condition; follow all their doctor's instructions, advice and recommendations.

Diet - a healthy diet will help keep blood pressure down. A healthy diet includes plenty of fruits and vegetables, whole grains and lean meats or fish.

Physical activity - regular physical exercise is ideal for maintaining healthy blood pressure levels; it also helps control such chronic conditions as diabetes and heart disease. Make sure you check with a qualified health care professional that your exercise program is ideal for your age, weight and health.

Avoid - abusing alcohol and drugs. Avoid long-term exposure to heavy metals, such as lead. Avoid long-term exposure to fuels, solvents and other toxic chemicals.

Written by Christian Nordqvist
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

Article URL: http://www.medicalnewstoday.com/articles/172179.php

Main News Category: Urology / Nephrology

Also Appears In: Blood / Hematology,

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