By Maria Karalis, MBA, RD, LD

Nutrition is an important part of your dialysis treatment plan whether you are on hemodialysis (HD) or peritoneal dialysis (PD). To give forth your best in all aspects of your lifestyle, you need to make an effort to maintain yourself by eating enough of the right kinds of foods or less restricted foods.

If you are thinking about changing modalities or need to make an informed decision about which modality to begin, there are a lot of issues to consider. One thing to consider is what your diet will be like on HD versus PD. This article will give you a very brief overview of the differences in these diets.

Protein

Protein is needed to keep tissues healthy and replace old or damaged tissues. People on PD are advised to follow a diet higher in protein than those on HD because protein is lost through the peritoneal membrane with every dialysis exchange. Some proteins are also lost during HD, but not to the same degree as PD.

Protein is also important as an aid for the body in preventing infection. Since the potential for infection is always present with PD, it is important to maintain a protein-rich diet. During infection, people on PD are advised to eat 1 1/2 times more meat and meat substitutes than usual.

There are two kinds of protein. High quality (animal) comes from milk, meat, chicken, fish and eggs, and contains all the needed ingredients for tissue growth. Low quality (plant) comes from vegetables, breads, cereals, and lacks some ingredients that tissues need to grow. You need both proteins. Your renal dietitian will decide your protein needs.

In order for your body to use proteins for growth and repair, sufficient calories are needed. Calories are necessary for energy and for maintaining your body weight. Just as fuel gives power to cars, calories fuel your body and give you energy. If you are underweight, you may have to eat high-calorie foods. This is more of an issue with HD patients.

People on PD tend to gain weight over time from absorption of calories from the dextrose in the dialysate (some people absorb as much as 500-700 calories each day from their dialysate). To minimize unwanted weight gain, decrease calorie intake. This should be done by reducing concentrated sweets and fats. Exercise is also important in maintaining your body weight. As always, check with your doctor before starting any exercise program.

Potassium

Potassium is a mineral vital for regulating your heart. People on PD do not usually require a potassium restriction since they are receiving dialysis every day. In fact, some are usually advised to increase their potassium through diet or oral medication.

Most people on HD need to limit their intake of high potassium foods since potassium builds up in between dialysis treatments. Some foods high in potassium include bananas, tomatoes, oranges, exotic fruits and potatoes.

Phosphorous

As kidneys fail, they lose their ability to balance calcium and phosphorus. Phosphorus combines with calcium to keep teeth and bones strong. Unlike potassium, phosphorus is not removed well by HD or PD. High phosphorus levels can eventually lead to calcium and phosphorus deposits in the heart, skin, joints and blood vessels. As such, phosphorus must be controlled through diet and phosphate binders for HD and PD.  Phosphorus is found in almost all foods but is especially high in dairy products, cheese, dried beans, liver, nuts and chocolate.

Sodium

The amount of sodium allowed in HD and PD is the same. Sodium is limited to control thirst and keep blood pressure under control. For both HD and PD, food can be cooked with a small amount of salt, but no additional salt should be added to foods at the table.

On PD, sudden weight gain from fluids, elevated blood pressure or excessive thirst, may signal the need to cut back on sodium and/or fluid intake. Additionally in PD, excess water weight requires stronger, or higher, dialysate concentrations and consequently more calories are absorbed. This can eventually lead to an increased body weight.

Fluids

Healthy kidneys maintain fluid balance and prevent swelling in feet, ankles, legs, hands or face. When the kidneys lose their ability to get rid of extra fluid, excess water can raise blood pressure, cause strain on the heart and make it hard to breathe.

Fluid gain and fluid intake work the same for those on either modality. PD operates by putting 1-2 liters of fluid solution in the peritoneal membrane every few hours, depending on the dialysis. At the end of the exchange, the fluid is withdrawn. If more fluid is released than was put in, you will need to drink a little more. If less fluid is released than was put in, you will need to drink a little less.

One of the goals during HD is fluid removal. Less fluid gain between treatments results in better-tolerated treatments and is easier on the heart. Higher fluid gains can lead to cramping during dialysis and possibly longer treatment times (some people need extra treatment if all water weight is not removed). The goal for fluid gain should be no more than 1-2 pounds per day between treatments.

The fluid allowance for HD is determined by the amount of urine produced in a 24-hour period. Most people are limited to 700-1000 ml of fluid per day plus urine output. For example, if you urinate 500 cc, your total daily fluid allowance would be 1200 cc (500 + 700). Fluid allowances vary from person to person. Other considerations include how much the remaining kidney function is left and the person’s body size.

                                  Hemodialysis                                 Peritoneal Dialysis

     Protein                Based on needs           Based on needs; protein needs higher than HD  

     Calories            Based on needs            Based on needs; focus is on less sweets/fats to

                                                                     prevent unwanted weight gain from dextrose

                                                                     in dialysate

     Potassium         Limited                          Not usually limited    

     Phosphorus        Limited                         Limited           

     Sodium                Limited                         Limited          

     Fluid                    Limited                          Limited but can be more liberal than HD

Summary

The table above provides a summary of the differences in PD and HD diets. For more specific and individualized advice about your diet, please consult with your physician and Registered Dietitian.

Maria is the Nutrition Consultant for iKidney.com and has worked in the nephrology field for more than 14 years. She enjoys writing for both patients and healthcare professionals with one goal in mind: helping the CKD patient live their life to the fullest. Mrs. Karalis lives in Vernon Hills, Ill. with her husband and two children and can be reached at mariakaralis@yahoo.com.

The information contained herein is intended for educational purposes only. It is not intended and should not be construed as the delivery of medical care. Persons requiring diagnosis or treatment, or those with specific questions, are urged to contact their local healthcare provider for appropriate care.

This article originally appeared in the January 2005 issue of aakpRENALIFE, Vol. 20, No. 4.

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