Kidney failure facts
- Kidneys are the organs that help filter waste products from the blood. They are also involved in regulating blood pressure, electrolyte balance, and red blood cell production in the body.
- There are numerous causes of kidney failure, and treatment of the underlying disease may be the first step in correcting the kidney abnormality.
- Some causes of kidney failure are treatable and the kidney function may return to normal. Unfortunately, kidney failure may be progressive in other situations and may be irreversible.
- Symptoms of kidney failure are due to the build-up of waste products in the body that may cause weakness, shortness of breath, lethargy, and confusion. Inability to remove potassium from the bloodstream may lead to abnormal heart rhythms and sudden death. Initially, there may be no symptoms of kidney failure.
- The diagnosis of kidney failure usually is made by blood tests measuring BUN, creatinine, and glomerular filtration rate (GFR).
- Treatment of the underlying cause of kidney failure may return kidney function to normal. Lifelong efforts to control blood pressure and diabetes may be the best way to prevent chronic kidney disease and its progression to kidney failure. Usually, kidney function gradually decreases over time.
- If the kidneys fail completely, the only treatment options available may be dialysis or transplant.
What are the kidneys?
The kidneys are located in the abdomen toward the back, normally one on each side of the spine. They get their blood supply through the renal arteries directly from the aorta and send blood back to the heart via the renal veins to the vena cava. (The term "renal" is derived from the Latin name for kidney.)
The kidneys have the ability to monitor the amount of body fluid, the concentrations of electrolytes like sodium and potassium, and the acid-base balance of the body. They filter waste products of body metabolism, like urea from protein metabolism and uric acid from DNA breakdown. Two waste products in the blood can be measured: blood urea nitrogen (BUN) and creatinine (Cr).
When blood flows to the kidney, sensors within the kidney decide how much water to excrete as urine, along with what concentration of electrolytes. For example, if a person is dehydrated from exercise or from an illness, the kidneys will hold onto as much water as possible and the urine becomes very concentrated. When adequate water is present in the body, the urine is much more dilute, and the urine becomes clear. This system is controlled by renin, a hormone produced in the kidney that is part of the fluid and blood pressure regulation systems of the body.
Kidneys are also the source of erythropoietin in the body, a hormone that stimulates the bone marrow to make red blood cells. Special cells in the kidney monitor the oxygen concentration in blood. If oxygen levels fall, erythropoietin levels rise and the body starts to manufacture more red blood cells.
After the kidneys filter blood, the urine is excreted through the ureter, a thin tube that connects it to the bladder. It is then stored in the bladder awaiting urination, when the bladder sends the urine out of the body through the urethra.
Medically Reviewed by a Doctor on 2/4/2013
Diet
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Diet is an important consideration for those with impaired kidney function.
Consultation with a dietician may be helpful to understand what foods may or may
not be appropriate. Since the kidneys cannot easily remove excess water, salt, or potassium, these may need to be consumed in limited quantities. Foods high in potassium include bananas, apricots, and salt substitutes.
Phosphorus is a forgotten chemical that is associated with calcium metabolism and may be elevated in the body in kidney failure. Too much phosphorus can leech calcium from the bones and cause osteoporosis and fractures. Foods with high phosphorus content include milk, cheese, nuts, and cola drinks.
Medications
- Phosphorus-lowering medications (calcium carbonate [Caltrate], calcitriol [Rocaltrol], sevelamer [Renagel])
- Red blood cell production stimulation (erythropoietin, darbepoetin [Aranesp])
- Red blood cell production (iron supplements)
- Blood pressure medications
- Vitamins
Dialysis
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Dialysis cleanses the body of waste products in the body by use of filter
systems. There are two types of dialysis; 1) hemodialysis, and 2) peritoneal
dialysis.Hemodialysis
For this type of dialysis, access to the blood vessels needs to be surgically created so that large amounts of blood can flow into the machine and back to the body. Surgeons can build a fistula, a connection between a large artery and vein in the body, usually in the arm, that causes a large amount of blood flow into the vein. This makes the vein larger and its walls thicker so that it can tolerate repeated needle sticks to attach tubing from the body to the machine. Since it takes many weeks for a fistula to mature enough to be used, significant planning is required if hemodialysis is to be considered as an option.
If the kidney failure happens acutely and there is no time to build a fistula, special catheters may be inserted into the larger blood vessels of the arm, leg, or chest. These catheters may be left in place for up to three weeks. In some diseases, the need for dialysis will be temporary, but if the expectation is that dialysis will continue for a prolonged period of time, these catheters act as a bridge until a fistula can be planned, placed, and matured.
Dialysis treatments normally occur three times a week and last a few hours at a time. Most commonly, patients travel to an outpatient center to have dialysis, but home dialysis therapy is becoming an option for some.
Medically Reviewed by a Doctor on 2/4/2013