By Lori Hegel, RN, CNN

Hemodialysis patients have special diet and fluid needs to consider at all times, particularly while away from home. When you are on vacation, you may eat at restaurants for some of your meals and it can be difficult to know which foods to choose. If you eat too many foods that are high in potassium and/or phosphorus, you can expect the same problems you experience at home in this situation. You must also maintain your fluid intake, or you will have problems with your dialysis treatments and may have difficulty breathing as well.

It is important to remember that two and a half to five hour dialysis treatments will attempt to do what your kidneys used to do all the time. By following dietary and fluid limits, hemodialysis patients can lessen the extreme changes that occur during treatment. The nephrologist and dietitian have specifically designed the limitations of your diet and fluid intake. These restrictions are based on your body size, urine output and lab results. Generally, people on hemodialysis will need to limit the amount of potassium, phosphorus and sodium in their diet. This may not be easy. However, the consequences of not following the prescribed plan can be very harmful, especially over time. Following the diet and limiting fluid intake will generally make treatment more tolerable and help prevent skin, bone and heart problems.

POTASSIUM (K)

Potassium is a mineral found in many foods. We need potassium because it plays an important role in muscle function. However, too much potassium can cause your heart to stop beating, with few if any warning signs. Potassium is removed during the dialysis treatment. The safest way to control potassium in your blood is to limit what you eat as outlined on your dietary plan. The commonly prescribed amount per day for hemodialysis patients is between 1500 and 2000 mg. The following foods are high in potassium: citrus, bananas, potatoes, tomatoes, nuts and dried beans.

PHOSPHORUS (PHOS OR PO4)

Phosphorus is a mineral found in almost all foods. Phosphorus and calcium levels in the blood are closely related. Calcium affects muscle function (including your heart), allowing your bones to release calcium into the blood to make the level normal. If blood phosphorus levels are high, blood calcium levels will be low. If your bones continue to release calcium, they will become weak and may break easily. This is a vicious cycle, which can be corrected by eating foods lower in phosphorus and taking phosphate binders as directed. The dialyzer removes some of the phosphorus in the body. However, dietary control remains vital. Over time, phosphorus will accumulate in the soft tissues and cause your skin to itch. The commonly prescribed amount per day for hemodialysis patients is between 500 and 1200 mg. Some examples of foods high in phosphorus are milk, cheese, eggs, nuts, dried beans and liver.

SODIUM (NA)

Sodium is found in most foods. It can be especially high in pre-packaged foods like canned goods, frozen dinners and macaroni and cheese. Pickles and "fast foods" are also very high in sodium. The commonly prescribed amount per day for hemodialysis patients is between 1000 and 1200 mg. Read the nutrition labels on the food packaging for sodium amounts. Sodium can cause an increase in blood pressure, water retention, and most importantly, it makes you thirsty. The more you limit your sodium intake, the easier it is to follow your fluid restriction.

Most hemodialysis patients agree that fluid intake seems to be the most difficult part of diet restrictions to follow because they are frequently thirsty. Your nephrologist determines how much fluid you can have by considering the amount of urine you produce each day. The less urine you produce, the less fluid you should drink. Most nephrologists will expect you to limit your fluid intake to 1000-1500 ml/33-50 ounces per day.

If your kidneys were working normally, the fluid would be removed constantly. Since your kidneys are not able to remove all, or in some cases, any of the fluid, the dialysis treatment must remove two to three days of accumulated fluid from your body in a very short amount of time. This "fluid shift" can cause low blood pressure and/or muscle cramps, both of which can be severe, making your dialysis session very uncomfortable. Excessive fluid gains may cause long-term health problems. Continued "fluid overload" can cause your heart to lose its ability to pump blood effectively. Imagine your heart as a rubber band that stretches and springs back into shape. If you constantly overstretch the band, eventually it will not return to its original shape. The same is true of your heart.

When fluid intake exceeds the output, the remaining fluid accumulates in the blood stream, tissues and lungs. This causes swelling, shortness of breath and an increase in blood pressure because the heart has to pump harder to move the extra volume in the blood. Each time the heart has to adjust to the extra work, it becomes harder for it to return to its original shape. Because the heart is a muscle, this constant abuse eventually causes the heart to become enlarged and less able to move the blood through the body effectively. When this happens, the body will have more difficulty maintaining blood pressure and tolerating dialysis.

Most of these problems can be prevented by monitoring the fluid intake and following the fluid restrictions. Keep a fluid journal and remember that anything that turns to liquid at room temperature needs to be counted as fluid. (Yes, even Jell-O® and ice cream.) The key to a successful dialysis treatment in general is to follow your doctor's advice. The nurses, dietitians and social workers are available to help you develop a plan to stay within your limits. When you are faced with the challenge of eating at a restaurant or at someone's home, there are guides available to help you make better choices.

The American Association of Kidney Patients' "Na-K-Phos Counter." This booklet lists common foods and the amounts of sodium, potassium and phosphorus per serving. Fast food items are included.

The National Kidney Foundation (NKF) produces "Dining Out With Confidence: A Guide for Renal Patients." This brochure offers alternatives for common menu items.

By planning ahead through snack preparation, knowing in advance what restaurants in which you will be eating, or educating your family/friends about your dietary and fluid needs, you will be better equipped to succeed at home or on vacation.

Lori Hegel, RN, CNN, is the Patient Services Coordinator at the ESRD Network of Florida in Tampa, FL.

This article originally appeared in the January 2002 issue of aakpRENALIFE, Vol. 17, No. 4.

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