Chronic Renal Failure
Basics
Chronic renal failure (CRF)—is now called chronic kidney disease—is the gradual loss of the kidneys' ability to filter waste and fluids from the blood. Chronic kidney disease can range from mild dysfunction to severe kidney failure Figure 01.
The kidneys serve as the body's natural filtration system, removing waste products and fluids from the bloodstream and excreting them in the urine. The kidneys maintain the body's salt and water balance, which is important for regulating blood pressure. When the kidneys are damaged by disease or inherited disorders, they no longer function properly, and lose their ability to remove fluids and waste from the bloodstream. Fluid and waste products building up in the body can cause many complications. Most systems in the body, including the respiratory, circulatory, and digestive systems, are adversely affected by chronic kidney disease (CKD).
Figure 01. Anatomy of the renal system
Kidney disease can exist without symptoms for many years.
Renal failure progresses so gradually that CKD may not be detected until the kidneys are functioning at less than 25% of their normal capacity.
CKD occurs in 1 of every 5,000 people.
Chronic kidney disease usually occurs in middle-aged and older people, although children and pregnant women are also susceptible. Chronic kidney disease can lead to total kidney failure, also known as end-stage renal disease (ESRD). People with ESRD require either dialysis or a kidney transplant. If not properly managed, ESRD is fatal.
Causes
Underlying disease is usually responsible for CKD Table 01.
Diseases leading to kidney damage may be confined to the kidney, as in kidney infections, or may affect multiple organs, as in hypertension or diabetes. Approximately 40% of CKD patients have the disease as a result of diabetes, 30% have it as a result of hypertension, and 10% have it as a result of a disease called glomerulonephritis. Glomerulonephritis is a kidney disease that causes decreased output of urine, the spilling of blood and protein into the urine, and body swelling.
Diabetes mellitus is the most common cause of CKD.
Diabetes, a disease that disrupts the way the body uses blood sugar (glucose), can lead to kidney damage and CKD. The high levels of sugar damage the kidneys over several years, and results in a reduced ability to filter blood and excrete waste products in the urine.
High blood pressure that is ignored or inadequately treated for many years can lead to CKD Figure 02.
Hypertension, or high blood pressure, is a disorder that leads to damage of small blood vessels. When small blood vessels in the kidneys that filter the blood are damaged, kidney failure results. For this reason, it is important to keep blood pressure under control with medications, if necessary.
Figure 02. Blood pressure categories
CKD can result from a chronic kidney disease called glomerulonephritis, or from kidney infections.
Glomerulonephritis may cause a small output of urine, the spilling of blood and protein into the urine, and body swelling. Glomerulonephritis may have no symptoms for many years, but may eventually cause enough damage to the kidneys to lead to CKD. Long-term or repeated kidney infections can also damage the structure of the kidneys, reducing the kidney's capacity to filter blood.
Kidney stones and other blockages can lead to CKD.
Any obstruction in the natural flow of urine causes a back-flow of pressure in the kidney, which can damage the kidney's functional units, the nephrons. Nephrons are tiny tubular structures in the kidney that filter the blood. Each kidney has millions of nephrons. This damage can occur slowly over several years, and can ultimately lead to CRF.
Over-the-counter and prescription medications can contribute to CKD.
Several drugs cause damage to the kidneys, including over-the-counter pain medications and certain very powerful antibiotics. If taken regularly over long periods, these medications act like poisons to the kidneys. People with even mild kidney disease must be very careful about the prescription drugs and non-prescription drugs they use. If you have known kidney disease, you should discuss all medication usage with your doctor.
Other diseases and conditions may lead to CKD as part of their natural progression.
These include Alport syndrome, which is a rare kidney disease that causes kidney failure and hearing loss; lupus erythematosus; connective tissue diseases; kidney cancer; liver disease (cirrhosis); polycystic kidney disease; and abnormalities present at or before birth (congenital abnormalities).
Table 1. Causes of Chronic Kidney Disease
| Hypertension |
| Diabetes |
| Glomerulonephritis |
| Chronic kidney infections |
| Obstruction of the urinary path (kidney stones) |
| Medications |
| Inherited kidney diseases |
| Other medical conditions (lupus, cirrhosis) |
Symptoms
Many symptoms of chronic kidney disease occur late in the disease process Table 02.
Unfortunately, symptoms of CKD do not appear until the kidneys are operating at a fraction of their previous capacity. When symptoms do occur, they can include fatigue caused by anemia, shortness of breath, bad breath caused by a build-up of waste in the saliva and sweat, an unpleasant taste in the mouth, and itchy skin. Fluid imbalance in the body can cause swelling, high blood pressure, and symptoms of fatigue.
Table 2. Symptoms of Chronic Kidney Disease
| Fatigue due to Anemia, or reduction in red blood cell production |
| Bone and joint problems |
| Puffiness (edema) or swelling in the arms and feet |
| Bloody or foamy urine |
| Headaches |
| High blood pressure |
| Shortness of breath |
| Itchy skin |
| Lower back pain |
| Nausea, vomiting |
| Loss of appetite |
| Frequent hiccups |
| Easy bleeding or bruising |
| Nail abnormalities |
| Skin discoloration |
Risk Factors
Because the greatest number of CKD cases result from hypertension or diabetes, a family history of these diseases may put you at increased risk for CKD Table 03.
Inherited kidney diseases, such as autosomal recessive polycystic kidney disease and Alport syndrome, may lead to CKD.
Compared to the general population, African Americans are 3.9 times more likely to have CKD that progresses to total kidney failure, and are 6.7 times more likely to have that kidney failure that is associated with hypertension.
Table 3. Risk Factors for Chronic Kidney Disease
| Uncontrolled hypertension |
| Diabetes mellitus |
| Urinary tract obstruction (kidney stone) |
| Long-term use/abuse of pain killers |
| Cigarette smoking |
| Poor circulation |
| Inherited kidney diseases (autosomal dominant polycystic kidney disease, Alport syndrome, congenital abnormalities) |
Diagnosis
Chronic renal failure (CRF)—is now called chronic kidney disease—is the gradual loss of the kidneys' ability to filter waste and fluids from the blood. Chronic kidney disease can range from mild dysfunction to severe kidney failure Figure 01.
The kidneys serve as the body's natural filtration system, removing waste products and fluids from the bloodstream and excreting them in the urine. The kidneys maintain the body's salt and water balance, which is important for regulating blood pressure. When the kidneys are damaged by disease or inherited disorders, they no longer function properly, and lose their ability to remove fluids and waste from the bloodstream. Fluid and waste products building up in the body can cause many complications. Most systems in the body, including the respiratory, circulatory, and digestive systems, are adversely affected by chronic kidney disease (CKD).Figure 01. Anatomy of the renal system
Kidney disease can exist without symptoms for many years.
Renal failure progresses so gradually that CKD may not be detected until the kidneys are functioning at less than 25% of their normal capacity.
CKD occurs in 1 of every 5,000 people.
Chronic kidney disease usually occurs in middle-aged and older people, although children and pregnant women are also susceptible. Chronic kidney disease can lead to total kidney failure, also known as end-stage renal disease (ESRD). People with ESRD require either dialysis or a kidney transplant. If not properly managed, ESRD is fatal.
Underlying disease is usually responsible for CKD Table 01.
Diseases leading to kidney damage may be confined to the kidney, as in kidney infections, or may affect multiple organs, as in hypertension or diabetes. Approximately 40% of CKD patients have the disease as a result of diabetes, 30% have it as a result of hypertension, and 10% have it as a result of a disease called glomerulonephritis. Glomerulonephritis is a kidney disease that causes decreased output of urine, the spilling of blood and protein into the urine, and body swelling.
Diabetes mellitus is the most common cause of CKD.
Diabetes, a disease that disrupts the way the body uses blood sugar (glucose), can lead to kidney damage and CKD. The high levels of sugar damage the kidneys over several years, and results in a reduced ability to filter blood and excrete waste products in the urine.
High blood pressure that is ignored or inadequately treated for many years can lead to CKD Figure 02.
Hypertension, or high blood pressure, is a disorder that leads to damage of small blood vessels. When small blood vessels in the kidneys that filter the blood are damaged, kidney failure results. For this reason, it is important to keep blood pressure under control with medications, if necessary.Figure 02. Blood pressure categories
CKD can result from a chronic kidney disease called glomerulonephritis, or from kidney infections.
Glomerulonephritis may cause a small output of urine, the spilling of blood and protein into the urine, and body swelling. Glomerulonephritis may have no symptoms for many years, but may eventually cause enough damage to the kidneys to lead to CKD. Long-term or repeated kidney infections can also damage the structure of the kidneys, reducing the kidney's capacity to filter blood.
Kidney stones and other blockages can lead to CKD.
Any obstruction in the natural flow of urine causes a back-flow of pressure in the kidney, which can damage the kidney's functional units, the nephrons. Nephrons are tiny tubular structures in the kidney that filter the blood. Each kidney has millions of nephrons. This damage can occur slowly over several years, and can ultimately lead to CRF.
Over-the-counter and prescription medications can contribute to CKD.
Several drugs cause damage to the kidneys, including over-the-counter pain medications and certain very powerful antibiotics. If taken regularly over long periods, these medications act like poisons to the kidneys. People with even mild kidney disease must be very careful about the prescription drugs and non-prescription drugs they use. If you have known kidney disease, you should discuss all medication usage with your doctor.
Other diseases and conditions may lead to CKD as part of their natural progression.
These include Alport syndrome, which is a rare kidney disease that causes kidney failure and hearing loss; lupus erythematosus; connective tissue diseases; kidney cancer; liver disease (cirrhosis); polycystic kidney disease; and abnormalities present at or before birth (congenital abnormalities).
Table 1. Causes of Chronic Kidney Disease
| Hypertension |
| Diabetes |
| Glomerulonephritis |
| Chronic kidney infections |
| Obstruction of the urinary path (kidney stones) |
| Medications |
| Inherited kidney diseases |
| Other medical conditions (lupus, cirrhosis) |
Many symptoms of chronic kidney disease occur late in the disease process Table 02.
Unfortunately, symptoms of CKD do not appear until the kidneys are operating at a fraction of their previous capacity. When symptoms do occur, they can include fatigue caused by anemia, shortness of breath, bad breath caused by a build-up of waste in the saliva and sweat, an unpleasant taste in the mouth, and itchy skin. Fluid imbalance in the body can cause swelling, high blood pressure, and symptoms of fatigue.
Table 2. Symptoms of Chronic Kidney Disease
| Fatigue due to Anemia, or reduction in red blood cell production |
| Bone and joint problems |
| Puffiness (edema) or swelling in the arms and feet |
| Bloody or foamy urine |
| Headaches |
| High blood pressure |
| Shortness of breath |
| Itchy skin |
| Lower back pain |
| Nausea, vomiting |
| Loss of appetite |
| Frequent hiccups |
| Easy bleeding or bruising |
| Nail abnormalities |
| Skin discoloration |
Because the greatest number of CKD cases result from hypertension or diabetes, a family history of these diseases may put you at increased risk for CKD Table 03.
Inherited kidney diseases, such as autosomal recessive polycystic kidney disease and Alport syndrome, may lead to CKD.
Compared to the general population, African Americans are 3.9 times more likely to have CKD that progresses to total kidney failure, and are 6.7 times more likely to have that kidney failure that is associated with hypertension.
Table 3. Risk Factors for Chronic Kidney Disease
| Uncontrolled hypertension |
| Diabetes mellitus |
| Urinary tract obstruction (kidney stone) |
| Long-term use/abuse of pain killers |
| Cigarette smoking |
| Poor circulation |
| Inherited kidney diseases (autosomal dominant polycystic kidney disease, Alport syndrome, congenital abnormalities) |
The diagnostic exam will include a complete medical history, a physical, and blood, urine, and kidney function tests.
Laboratory tests will be run on the blood and urine of patients suspected of having CRF.
Blood tests will look for abnormal concentrations of substances such as creatinine, blood urea nitrogen (BUN), uric acid, phosphate, sodium, and potassium. Elevated levels of these wastes indicate that the kidneys are not functioning properly.
Urine samples will also be collected, usually over a 24-hour period. Before the test, the provider will ask if you are taking certain prescription medications, such as Cimetidine (Tagamet, Tagamet HB), Trimethoprim (Bactrim, Cotrim, Septra, Sulfamethoprim, Uro-D/S, Uroplus), and Cefazolin (Ancef, Kefzol, Zolicef), as these drugs may alter laboratory results.
Radiological exams can help determine the cause of kidney failure, and level of remaining kidney function.
Your doctor may perform an ultrasound examination of the kidneys, bladder, and/or ureters. In an ultrasound, high-frequency sound waves passed result in a picture of your kidneys. Other detailed imaging studies that the doctor may run include x-rays, computer tomography (CT), or magnetic resonance imagery (MRI) scans.
A provider might remove a small section of kidney tissue to look for microscopic tissue damage under a microscope. This procedure is called a biopsy, and is performed under local anesthesia.
Because several disorders may lead to CKD, treating these underlying disorders may prevent or delay the progression of CKD.
People with diabetes can prevent CKD by controlling their blood sugar and blood pressure as strictly as possible, and by not smoking. People with diabetes can also take a certain type of blood pressure medicine to help prevent kidney disease.
Following a low-protein diet and maintaining healthy cholesterol levels can also help to slow the progression of CKD.
People in the early stages of CKD should avoid medications that are known to be toxic to the kidneys, and avoid dehydration, which can strain the kidneys, and make the CKD worse.
Prevention and Screening
Because several disorders may lead to CKD, treating these underlying disorders may prevent or delay the progression of CKD.
People with diabetes can prevent CKD by controlling their blood sugar and blood pressure as strictly as possible, and by not smoking. People with diabetes can also take a certain type of blood pressure medicine to help prevent kidney disease.
Following a low-protein diet and maintaining healthy cholesterol levels can also help to slow the progression of CKD.
People in the early stages of CKD should avoid medications that are known to be toxic to the kidneys, and avoid dehydration, which can strain the kidneys, and make the CKD worse.
Treatment
If late-stage symptoms such as decreased alertness, seizures, and coma develop, seek immediate medical attention. Other serious symptoms include shortness of breath and extensive swelling of the lower legs. People who have CKD have a higher risk of developing dangerously high levels of blood potassium, which can lead to life-threatening arrythmias.
A high-carbohydrate, low-protein, low-salt diet can reduce the workload on the kidneys. Also, it is important to balance your fluid intake to your urine output to avoid dehydration.
Patients with CKD may need to adhere to a strict diet to control symptoms and avoid complications. Common dietary recommendations include:
Proper treatment of underlying medical conditions, including hypertension and diabetes, can also minimize the progression of CKD.
To relieve the stress of illness, patients may seek support groups where members share similar experiences and problems related to CKD.
Your doctor is the best source of information on the drug treatment choices available to you.
Patients with severe CKD may need dialysis, which is a procedure that filters and cleans the blood when the kidneys no longer can do so.
There are two types of dialysis: peritoneal dialysis and hemodialysis. In peritoneal dialysis, a special tube is inserted through the skin into the abdomen. Through the tube, a cleansing fluid called dialysate flows into the abdomen and is drained several hours later. Wastes that have been removed from the blood by the dialysate are also drained. This process is repeated several times per day, or can be done at night while the patient sleeps.
In hemodialysis, a dialysis machine filters the blood. Through one set of tubes, blood leaves the body and travels into the dialysis machine where wastes and extra fluids are removed. Filtered blood then flows back into the body through another set of tubes. While the number of treatments and duration of each treatment varies depending on the severity of the patient's condition, the average dialysis patient undergoes treatment three times a week for three or four hours at each visit. Most people on dialysis in the U.S. undergo hemodialysis. New machines are being developed so that people can undergo hemodialysis at home.
For most people with ESRD, dailysis should be a bridge to a kidney transplant. Patients with CKD who are headed for dialysis should be place on the transplant list early.
Kidney transplants are the most common form of organ transplants, after cornea transplants. A kidney transplant can come from either a living (usually a blood relative) or a recently deceased person. There are restrictions on who is elligible for a transplant.
Unfortunately, the demand for transplanted kidneys far exceeds supply. In the U.S. in 1996, only 11,330 living kidney donor transplants were performed, despite over 34,000 people on the kidney transplant waiting list. Living donor kidneys have a 50% chance of functioning for 24 years, and kidney transplants from cadavers have a 50% chance of functioning for nine years.
Congenital kidney and urinary tract abnormalities are the main cause of CKD in children younger than five years old.
Hereditary kidney diseases emerge in children between the ages of 5 and 15 years old. When CKD develops in infancy, the child's growth is more impaired than if the disease develops during the teenage years. CKD may be more difficult to manage in children.
Fertility and libido are impaired by CKD, and pregnant women with CKD are less likely to carry their pregnancies to term than otherwise healthy women. Most women with CKD can still have children, but women with ESRD on dialysis are advised not to have children.
Older adults experience the highest incidence of CRF, as renal disease usually occurs secondary to several age-related conditions, including diabetes and hypertension.
In older patients, it is important to rule out hypercalcemia (high blood calcium), renal artery blockage, use of medications that are toxic to the kidney, and kidney stones as the cause of renal symptoms.
There is no present medical therapy that can reverse CKD.
If left untreated, CKD usually progresses to end-stage renal disease (ESRD). When compared with the general population, patients with CKD leading to ESRD have a significantly shortened life span.
Early diagnosis and conservative management of renal failure is essential for improving quality of life and extending the lifespan of CKD patients. Lifelong treatment may be necessary to control the symptoms of CKD.
Because symptoms can quickly worsen and complications can arise, patients with CKD should be observed closely.
A provider may recommend that a patient monitor his or her blood and urine chemistries, blood pressure, and blood volume frequently.
Possible complications associated with CKD include: