Chronic kidney disease
Chronic kidney disease involves a gradual decrease in kidney function. Once CKD becomes advanced, the kidneys are no longer able to filter properly, which can allow dangerous levels of wastes, fluids, and electrolytes to build up in the body. CKD affects an estimated 14 percent of Americans.
Definition & Facts
The kidneys only weigh about five ounces each, but they filter approximately 200 liters of blood and produce about 2 liters of urine on a daily basis. The wastes that the kidneys filter come from foods, fluids, and the natural breakdown of tissue. The kidneys regulate levels of phosphorus, sodium, and potassium that are necessary for life but are dangerous at high levels.
The kidneys also release three vital hormones. Renin is a hormone instrumental in regulating blood pressure. Erythropoietin is necessary for the bone marrow to produce red blood cells. Calcitriol, a form of vitamin D, regulates chemical balance and helps maintain calcium levels for healthy bones.
Symptoms & Complaints
- Changes in urination. This can include urinating more or less frequently, difficulty urinating, changes in the color of the urine, blood in urine, and bubbly or foamy urine.
- Swelling. As the kidneys become unable to remove excess fluid, individuals with CKD may experience swelling, especially in the feet, ankles, legs, hands, and face.
- Itching or rash. The excess waste accumulating in the bloodstream can cause rashes and severe itching.
- Nausea and vomiting. The buildup of waste can affect appetite and cause nausea and vomiting.
- Ammonia breath/metallic taste in the mouth. This is due to the accumulation of waste and ammonia in the bloodstream.
- Symptoms of anemia. As the kidneys produce less erythropoietin, there are fewer red blood cells to carry oxygen throughout the body. This can cause symptoms such as fatigue, feeling cold, shortness of breath, dizziness, and difficulty concentrating.
- Altered mental status. The accumulation of wastes and uremic poison can cause a condition called encephalopathy, which can lead to decreased mental acuity and personality changes.
- High blood pressure that is difficult to control with normal blood pressure medications.
Any disease or condition that damages the structures or blood vessels of the kidneys can result in chronic kidney disease. High blood pressure and diabetes are the most common causes of CKD. Both conditions can damage blood vessels in the kidneys and eventually impair kidney function. The damage typically occurs gradually if blood sugar and blood pressure remain uncontrolled over a prolonged period. Other factors that can cause kidney damage include:
- A blockage or narrowing of the renal artery supplying blood to the kidneys.
- Kidney infections or conditions such as polycystic kidney disease.
- Long-term use of NSAIDs or other medications that are metabolized by the kidneys.
- Cardiovascular factors, including cardiovascular disease and high cholesterol.
- Abuse of alcohol or illicit drugs.
The risk for CKD increases with age as the kidneys naturally become smaller. Males and individuals of African-American, Asian-American, or Native American descent are also at higher risk for CKD.
Diagnosis & Tests
A variety of tests and procedures are used to evaluate kidney function and make a definitive diagnosis of chronic kidney disease. Blood tests are used to measure the levels of waste products, such as creatinine and urea, that are present in the bloodstream as well as to check for imbalances in calcium, potassium, and phosphorous. A urinalysis may be used to test for the presence of protein, blood, or sugar that should not be present in normal urine.
Ultrasounds and other imaging tests may be used to check for abnormalities in the shape or structure of the kidneys. Ultrasounds are also useful in ruling out kidney stones or other obstructions that may affect kidney function.
A needle biopsy performed under local anesthesia may be used to obtain a small sample of kidney tissue for further analysis to determine the underlying cause of the renal failure. Once a patient is diagnosed with CKD, the disease is staged according to the level of kidney function:
- Stage 1—Kidney function is greater than 90 percent.
- Stage 2—Patient has 60 to 89 percent of kidney function.
- Stage 3—Kidney function is between 30 and 59 percent.
- Stage 4—Patient only has 15 to 29 percent of kidney function.
- Stage 5—Kidney function is less than 15 percent
Treatment & Therapy
It may be possible to treat certain instances of kidney disease depending on the underlying cause. In most cases, though, there is no cure, and treatment is focused on controlling symptoms, slowing the progression of the disease, and limiting complications. If CKD is caused by diabetes or high blood pressure, treatment is aimed at managing those conditions.
Blood pressure medications known as ACE inhibitors are particularly helpful in protecting the kidneys. CKD can cause an increase in levels of cholesterol, so the doctor may prescribe a statin to reduce the risk of heart disease.
Erythropoietin supplements can increase the production of red blood cells and combat symptoms of anemia. Diuretics can decrease fluid retention and help the body maintain a proper fluid balance. Vitamin D supplements and calcium supplements can assist in strengthening bones and reduce the risk of bone fracture.
Once an individual reaches near-complete or complete kidney failure, the only treatment options are dialysis or organ transplant. If a patient chooses not to pursue dialysis or transplant, treatment will typically focus on comfort measures and life expectancy is normally only a few weeks.
Prevention & Prophylaxis
- Limit alcohol consumption.
- Follow dosing information for all medications.
- Stop smoking.
- Maintain a healthy weight.
- Work with a healthcare professional to manage health conditions that increase the risk of CKD.
Individuals with impaired kidney function should collaborate with a doctor or dietician to implement the proper renal diet, including limiting salt intake, choosing foods low in potassium, and restricting the consumption of protein.