End Stage Renal disease - diet; Hemodialysis - diet; Kidney diet - dialysis patients
This article describes the diet necessary in patients with end-stage kidney disease on either hemodialysis or peritoneal dialysis. The diet is usually high in protein and low-sodium, low-potassium, and low-phosphorus. Fluid intake is also restricted.
The purpose of this diet is to maintain a balance of electrolytes, minerals, and fluid in patients on dialysis. The special diet is important because dialysis alone does not effectively eliminate ALL waste products. These waste products can also accumulate between dialysis treatments.
Most dialysis patients urinate very little or not at all, and therefore fluid restriction between treatments is very important. Without urination, fluid will accumulate in the body and cause excess fluid in the heart, lungs and ankles.
Patients on dialysis need a high protein intake to maintain adequate nutrition. Patients can become malnourished on dialysis and this often predicts a poor outcome.
The diet will help dialysis patients feel as good as possible.
The dialysis diet controls the intake of fluid, protein, sodium, potassium, and phosphorus. The controlled amounts of each of these nutrients are based on the person’s blood levels of sodium, potassium, phosphorus, calcium, albumin, and urea measured before and immediately after a dialysis treatment.
Fluid restriction is based on the amount of urine output and weight gain between dialysis treatments.
The following are some general dietary recommendations for dialysis patients.
Pre-dialysis patients are often asked to limit protein intake to slow the progression of kidney disease. This changes with the start of dialysis: the patient now needs much more protein. Patients on peritoneal dialysis need even higher protein, because a large amount of protein can be lost in the peritoneal fluid which is discarded.
However, dialysis patients still need to limit salt, potassium and phosphorous, which makes it a little challenging to get enough protein. Moreover, many dialysis patients have poor appetites, especially early after start of dialysis. Every dialysis center has a dietician who can explain the dietary modifications required, suggest food selection, and prescribe supplements as required.
Most patients need to control the sodium (salt) content in their diet. This helps maintain fluid balance in the body to avoid fluid retention and elevated blood pressure.
The daily intake of potassium is also controlled. This helps prevent hyperkalemia (a high level of potassium), a common problem for people on dialysis.
The mineral phosphorus is also controlled by this diet. Phosphorus is not effectively removed by dialysis treatments. Patients need to reduce their intake of dairy products and other foods high in phosphorus.
They are usually prescribed calcium supplements, which bind the phosphorus in food. It is important to take these calcium tablets with meals. Some patients may be given a non-calcium phosphorus binder, such as Renagel. The amount of binders that need to be taken by each patient is determined by their blood levels of phosphorus and their intake of phosphorus-containing foods in the diet.
During kidney failure, the amount of urine produced drops. The urine output usually stops completely once patients have been on dialysis for more than 6 months. Patients on peritoneal dialysis usually retain their urine output for a longer time and have less restriction on fluid intake.
The recommended daily amount of fluid is based on the amount of urine produced in a 24-hour period and the amount of weight gained between dialysis treatments. Other considerations are the amount of fluid retention, the level of dietary sodium, and whether the patient has congestive heart failure.
Patients on peritoneal dialysis usually have less restriction on their fluid, sodium, and potassium intake as they have dialysis treatments every day. The intake of these substances needs to be individualized in these patients.
People with kidney disease are more prone to heart disease and often need to follow a low-fat diet. The daily calorie intake needs to maintain the person’s nutritional status and prevent the breakdown of body tissue. The person’s weight and protein status should be monitored regularly.
Vitamin supplementation is usually needed. The requirements for the fat-soluble vitamins (A, D, E, and K) are usually met by the diet. Vitamin D is supplemented depending on calcium, phosphorus, and parathyroid hormone levels. Vitamin D is usually given intravenously during the dialysis treatment.
The patient’s intake of water-soluble vitamins is often inadequate, as several good food sources of water-soluble vitamins are restricted on this diet. Water-soluble vitamins are also lost during the dialysis treatments. All dialysis patients should receive supplementation of water-soluble vitamins.
The minerals calcium and iron are monitored. Supplementation of daily calcium depends on the patient’s blood calcium levels. Calcium is also given in the dialysis solution and is adjusted according to the blood calcium levels. Iron supplementation is based on iron studies, usually monitored every 3 months. Most dialysis patients are iron deficient and receive intravenous iron during dialysis treatments.
The Kidney Foundation has chapters in most states and is an excellent resource for educational materials and programs for people on dialysis and their families.
Most dialysis centers have registered dietitians who work with patients and physicians to educate the patients about their diet while on dialysis.
by David A. Scott, M.D.