End-Stage Renal Disease: Overview and Risk Factors
Chronic kidney disease is a syndrome in which the kidneys lose their ability to function. Normally, the kidneys filter the blood, produce urine, excrete wastes, and maintain electrolyte balance. End-stage renal disease (ESRD) is the most severe form of chronic kidney disease. It is characterized by severely limited kidney function that is insufficient to maintain the kidney's normal actions. Thus, patients with ESRD require renal replacement therapy via dialysis or kidney transplantation.
Life expectancy for ESRD patients has improved since the advent of dialysis in the 1960s. Nonetheless, the five-year survival is less than 50 percent.
Symptoms may include shortness of breath, nausea, vomiting, poor appetite, weight loss, lethargy, confusion, itching, electrolyte imbalances, seizures, and coma. Further, more than half of patients with ESRD are malnourished, which is associated which increased risk of death.
African-Americans have a significantly higher prevalence of chronic kidney disease compared with other racial groups, due, in part, to higher rates of hypertension. Other risk factors for chronic kidney disease and ESRD include:
- Older age
- Family history of chronic kidney disease
- Urinary tract disorders (e.g., kidney stones and urinary tract obstruction)
- Systemic medical disorders: diabetes mellitus, hypertension, autoimmune disorders (e.g., systemic lupus erythematosus), and systemic infections
- Medications that can be toxic to the kidneys: for example, nonsteroidal anti-inflammatory drugs (e.g., ibuprofen) and contrast dye
- Tobacco use
- The evaluation begins with a medical history and a physical examination.
- Blood testing to measure kidney function is generally performed.
- Testing to determine the underlying cause may include urine testing, ultrasound and CT scan of the kidneys, and kidney biopsy.
In general, ESRD is irreversible. Treatment is aimed at treating the complications and replacing renal function via dialysis or transplantation.
- Kidney transplantation is often the treatment of choice. Early identification of kidney replacement candidates is important so that adequate preparation and planning can be done. Referral to a nephrologist should occur as early as possible in order to plan for long-term therapy.
- There are two options for dialysis. Both methods have advantages and disadvantages, and outcomes are similar.
The most widely used method is hemodialysis, which involves the creation of a dialysis port, usually in the arm, and treatment at a dialysis center, typically three times a week.
The other option is continuous peritoneal dialysis, which involves inserting the dialysis material into the patient's abdomen and allowing dialysis to occur continuously or intermittently without need for the patient to travel regularly to a dialysis center.
- It is essential to treat ESRD complications that may arise. These include hypertension, excessive body fluids, electrolyte imbalances (e.g., high potassium, low calcium, and high phosphate), and anemia.
- Psychiatric disorders are common and can interfere with treatment. Adherence to recommended diet and fluid restrictions increases life expectancy and can help to reduce medical complications, treatment side effects, and improve quality of life. However, psychiatric disorders may interfere with treatment compliance.
Depression is the most common psychiatric problem in ESRD patients. Antidepressant treatment with medications and psychotherapy combined is not only effective in improving mood, but also improves nutritional status in dialysis patients.
- Exercise should be encouraged in ESRD patients. Exercise training in patients with ESRD and hypertension reduces blood pressure and has other cardiovascular benefits, such as reducing the risk for cardiac arrhythmias and functioning of the heart. Exercise also reduces the occurrence of depression.
End-Stage Renal Disease: Nutritional Considerations
- Weight maintenance and protein requirements: Protein and calorie needs are higher in patients with ESRD due to losses that occur during dialysis. If protein-calorie needs cannot be met with the usual diet, patients should be offered dietary supplements or, if necessary, tube feeding to achieve adequate protein and calorie intake.
- Sodium and potassium balance: ESRD patients should avoid high-sodium diets. Many patients on dialysis can effectively control blood pressure without drugs on a low-sodium (2 grams per day) diet.
A high-potassium diet is normally desirable to control blood pressure and reduce risk for stroke; however, individuals with ESRD on hemodialysis cannot tolerate this diet because they are unable to excrete potassium. Therefore, ESRD patients may need to avoid such foods as bananas, melon, legumes, potatoes, tomatoes, pumpkin, winter squash, sweet potato, spinach, orange juice, milk, and bran cereal to prevent high potassium levels, which can result in life-threatening arrhythmias. In contrast, patients on peritoneal dialysis more often suffer from low potassium levels, requiring an increase in potassium-containing foods and even potassium supplementation.
- Fluid restriction: It is essential that ESRD patients restrict their fluid intake in order to control blood pressure and avoid heart failure. The typical fluid allowance for patients on dialysis is 700 to 1,000 milliliters a day.
- Phosphorus: Elevated blood phosphorus levels can increase risk of cardiovascular disease and death in ESRD patients. Patients should be careful to avoid phosphate intake from processed foods. In addition, too much protein intake (more than 50 grams per day) can increase phosphate levels.
- Micronutrient supplements: Micronutrient supplements are essential for ESRD patients. Individuals on dialysis commonly have deficiencies of vitamin C, folate, vitamin B6, calcium, vitamin D, iron, zinc, and selenium. The National Kidney Foundation clinical practice guidelines for nutrition in chronic renal failure suggest that patients achieve 100 percent of the Dietary Reference Intakes (DRI) for vitamins A, C, E, K, thiamin (B1), riboflavin (B2), pyridoxine (B6), vitamin B12, and folic acid, as well as 100 percent of the DRI for copper and zinc. As a result of restricted intake of many foods and losses of water-soluble vitamins during dialysis, patients are usually given specially formulated vitamins.
Certain other dietary supplements may be helpful. Supplementation with L-carnitine has been approved by the U.S. Food and Drug Administration to prevent and treat carnitine deficiency in dialysis patients. L-carnitine has also been found to improve fat metabolism, protein nutrition, antioxidant status, and anemia. Nevertheless, inadequate evidence exists for the routine use of carnitine in patients who do not show signs of deficiency. Both vitamin C (250 milligrams a day) and vitamin E (400 International Units a day) have proven effective for treating painful muscle cramps. However, additional clinical trials are required before these can be used as standard therapy.
- Saturated fat and cholesterol: Dialysis patients should follow a diet low in saturated fat and cholesterol. These patients are at high risk for development of coronary artery disease. They often have increased triglycerides and decreased HDL ("good") cholesterol. Although they must eat a relatively high-calorie diet, patients on dialysis should avoid foods that raise triglycerides and cholesterol concentrations (see Hyperlipidemia).