Chronic Renal Failure Diagnosis

  • 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).

    Click to enlarge: Anatomy of the renal system

    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.

    Click to enlarge: Blood pressure categories

    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.

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