This is an abbreviated version of the complete article.*
Renal failure is the loss of kidney function. Renal failure can be acute, meaning the kidneys suddenly stop working, or chronic, meaning the kidneys slowly and progressively lose their ability to function.
When the kidneys cannot function normally, waste products and excess water accumulate throughout the body.
The most common causes of renal failure are related to longstanding hypertension and diabetes mellitus. Trauma, infection, congenital problems such as polycystic kidney disease, exposure to chemicals or medications, and vascular problems such as atherosclerosis (hardening of the arteries) also cause the kidneys to fail.
Renal failure may be permanent or reversible. A wide variety of treatments is available for both forms.
The kidneys, two small bean-shaped organs, are located on both sides the spine, below the ribcage. Blood flow through the kidney normally allows the kidney to excrete wastes, concentrate urine, and conserve electrolytes (mineral salts). Any condition that significantly interferes with blood flow to the kidney can result in renal failure:
There are three stages of renal failure:
Acute renal failure;
Chronic renal failure; and
End-stage renal failure.
The kidney cannot filter the waste and water adequately in any of these stages, but the severity of the condition varies widely. End-stage renal failure is the last stage of chronic renal failure and often requires dialysis or kidney transplantation as life-saving measures.
WHAT ARE THE SYMPTOMS OF RENAL FAILURE?
Renal failure typically causes nausea and vomiting, along with other symptoms that depend on the stage.
Paying attention to the symptoms of acute renal failure is crucial. The condition can be fatal if it is not diagnosed and treated within days. Symptoms may include:
Greatly reduced urine output;
Drowsiness and headache; and
Chronic renal failure, which develops slowly, can have vague and sporadic symptoms. Typically, the syndrome begins with a feeling of weakness and a loss of appetite, followed by:
Frequent urination, especially at night;
Pale, itchy, and easily bruised skin;
Shortness of breath;
A sensation of pins and needles in the hands, feet; or other areas and
End-stage renal disease, a severe illness, produces noticeable symptoms, such as:
Greatly reduced volume of urine;
Swelling of the face, limbs, and abdomen;
Very itchy skin; and
Breath that smells like ammonia.
CAUSES AND RISK FACTORS
In general, renal failure results when weak blood flow prevents the kidneys from filtering the blood properly. Specific causes include:
Vascular diseases such as atherosclerosis, or hardening of the arteries, which can block the renal artery or aorta;
Vascular surgery, which can occasionally dislodge a small piece of cholesterol or plaque deposit that travels to the kidney (called an atheroembolism);
Allergic reactions; and
Risk factors for kidney failure include:
High blood pressure;
Sickle cell anemia;
Abuse of alcohol or drugs; and
Long-term use of pain medications such as aspirin.
Duplex ultrasound evaluates blood flow and tissue structure.
To diagnose renal failure, a physician may order blood and urine tests to look for abnormal levels of blood chemicals. Some of these tests include:
Blood urea nitrogen;
Blood creatinine; and
Urine studies, such as for excessive amounts of protein.
Other exams establish the cause of the renal failure. They include:
Radionuclide scanning (A radioactive substance injected into a patient's bloodstream emits gamma rays, similar to x rays. A gamma camera collects these rays to assess blood flow through the kidneys.)
Abdominal duplex ultrasound (Two-dimensional sound wave imaging, combined with Doppler technology, emits and receives short pulses of sound waves to capture the movement of blood.)
Venacavography (A contrast agent is injected into the veins and an x ray is taken.)
Renal arteriography (Similar to venacavography, but provides images of arteries, not veins.)
Magnetic resonance angiography (MRA)
Computed tomography (CT) scan
In general, acute renal failure is reversible, while chronic renal failure is not and eventually leads to end-stage renal disease.
Patients who experience acute renal failure may be given the following:
Intravenous antibiotics and other medications; and
Dialysis, which filters the blood through an external artificial kidney machine.
Once acute renal failure is stabilized, physicians must address the underlying conditions. For example, the physician may recommend angioplasty or other treatments that improve or restore blood flow to the kidney.
Patients with chronic renal failure must also receive treatment (such as medications) for any underlying condition, such as diabetes or high blood pressure. Additionally, physicians may recommend a low-protein, low-salt diet, limiting water intake, and restricting potassium and phosphorus consumption. The patient may also take medications to treat renal failure complications, such as anemia.
Patients with end-stage renal failure need dialysis until a suitable kidney donor can be found.
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