Dialysis replaces some of the many different functions of the kidney, but it does not replace them all. Patients who begin peritoneal dialysis or hemodialysis are still monitored regularly, which includes routine blood and urine tests -- if the patient is still producing urine. The results of these tests determine how vigilant you have to be regarding diet. Never change your diet without consulting your nephrologist or dialysis provider.
Potassium
Differences between intracellular and extracellular levels of calcium make it possible for nerves to fire. Nerves function best when potassium levels remain within a very narrow range. However, when kidney function declines, potassium levels tend to creep up. Nerves can misfire, leading to irregular heart beats or even heart attacks. Hemodialysis is not particularly effective at removing potassium from the blood, so patients often need to continue the low-potassium diet they were on before starting dialysis. Peritoneal dialysis is better in this regard because it is more effective in removing potassium.
Low Potassium Foods
If you must restrict dietary potassium, a good potassium counter such as the U.S. Department of Agriculture database is indispensable because potassium is found in almost every food. Generally, foods with less than 200 mg potassium are considered low potassium.These include 1 medium apple, 1/2 cup rice, 1/2 cup green beans, 8 oz. coffee and 1/2 ear corn. Portion sizes are very important because a low-potassium food can easily become a high-potassium food.
Phosphorus
When renal function declines, phosphorus levels rise.This is dangerous because it causes calcium to leach out of the bones. Neither hemodialysis or peritoneal dialysis is particularly good at removing excess phosphorus. Excess phosphorus is controlled by taking a special type of drug known as a phosphorus binder and by limiting dietary phosphorus. Dairy products and legumes are high phosphorus foods, as are beer and chocolate.
Protein
Before dialysis, some patients with high urine protein are told to limit protein intake because it may accelerate the loss of renal function. As renal failure sets in, many patients find that eating even moderate amounts of protein aggravates symptoms of renal failure such as nausea. This changes when you are on dialysis. Since dialysis removes some amino acids from the blood, patients can compensate by eating more protein.
Sodium
Since the kidneys are involved in the regulation of blood pressure, hypertension is common even in the early stages of kidney disease. This problem doesn't go away after you start dialysis. Many patients continue to take four or five different types of blood pressure medication. Maintaining a low-sodium diet helps control this problem.
References
- National Kidney Foundation: Potassium and Your CKD Diet
- Davita; Potassium, Phosphorus and the Dialysis Diet; Helen Dorrough
- National Kidney Foundation: Phosphorus and your CKD Diet
- National Institutes of Diabetes, Digestive and Kidney Diseases: Chronic Kidney Disease-Mineral and Bone Disorder; February 2009
- National Institutes of Diabetes, Digestive and Kidney Diseases: Eat Right to Feel Right on Hemodialysis; August 2008
