American Medical Association Family Medical Guide - American Medical Association [542]
Acute Kidney Failure
If a person’s kidneys suddenly stop functioning, it is usually for one of three reasons: exposure to toxic agents, an immune reaction to a drug, or the result of an infection or disease that affects the kidneys, such as acute glomerulonephritis (see page 807). A sudden drop in blood pressure from a serious burn, severe bleeding, or a major heart attack can deprive the kidneys of an adequate supply of oxygen-rich blood, damaging them. The flow of urine may be suddenly and completely obstructed by a blockage in the urinary tract, such as in the urethra from an enlarged prostate gland (see page 832) or from a crushing injury in which myoglobin (the oxygen-carrying pigment of muscle) filters through the network of tiny blood vessels inside the kidneys and blocks the kidney’s microscopic filtering tubes.
If the kidneys cannot produce urine, waste products build up in the bloodstream, and water accumulates in the body. A dangerous imbalance of essential body chemicals that are normally regulated by the kidneys may develop.
Symptoms
In acute kidney failure, you may pass significantly less urine than usual, possibly less than a cup a day. Almost immediately, you will lose your appetite, feel increasingly nauseated, and begin to vomit. Delaying treatment can lead to drowsiness, confusion, seizures, coma, and death.
Diagnosis
Acute kidney failure is a medical emergency that requires immediate treatment in a hospital. If the cause of kidney failure cannot be determined easily, you will probably undergo an intensive series of diagnostic tests, including blood and urine tests; an ultrasound (see page 111), CT scan (see page 112), or MRI (see page 113) of the kidneys; and possibly an aspiration biopsy. In an aspiration biopsy, a small sample of kidney cells is removed through a hollow needle and examined under a microscope.
Treatment
If the cause of acute kidney failure is heavy bleeding or a heart attack, the person must be treated for shock (see page 579). If the cause of acute kidney failure is a urinary tract obstruction, surgery will be performed to eliminate the blockage. If the underlying cause of acute kidney failure is kidney disease, or if the kidneys remain severely affected after the cause of the failure has been treated successfully, additional treatment will be determined by the doctor.
If shock or severe fluid loss (from hemorrhaging, vomiting, or diarrhea) has led to acute kidney failure, the doctor will administer an intravenous saline (salt) solution, plasma (the fluid in which blood cells are suspended), or blood, sometimes with an adrenalinelike substance, to restore blood pressure to a more normal level and improve blood flow to the kidneys.
Diuretics (drugs that help remove excess water from the body by increasing the amount of water in urine) occasionally can help reestablish urine flow, but only after fluid loss is restored to the bloodstream by fluids given intravenously (through a vein). Kidneys can recover most or all of their lost function within a few days to several weeks. In some cases, such as in acute glomerulonephritis, treatment with medication may be effective. But when little or no urine is being formed and kidney damage is severe, a doctor will recommend kidney dialysis (see next page), a treatment that takes over the function of the kidneys until they recover.
While you are being treated, you may need to follow a special diet that is high in calories and low in protein and includes no more than 1 liter of fluid per day. This diet will provide the energy you need without overtaxing your kidneys.
Chronic Kidney Failure
Chronic kidney failure ultimately leads to end-stage kidney failure (see page 819), in which dialysis (see