The renal diet and progression of CKD

Background

Staging the severity of chronic kidney disease CKD (Stages 1-5) began in 2001 when nephrologist Andrew Levey introduced the concept at the annual Spring Clinicals meeting of the National Kidney Foundation. A decade later in 2012, staging now includes checking for albuminuria or protein in the urine, because this can be treated with medications.

Staging of kidney disease is important in determining when to start dialysis, and uses the patient’s glomerular filtration rate (GFR) to chart the progression of the disease. As the GFR decreases, renal replacement therapy will be needed.

Figure 1. Staging of chronic kidney disease based on GFR

G1 Normal filtration (more than 90 ml/min)

G2 Mildly decreased (60-89 ml/min)

G3a Moderately decreased kidney function (45-59 ml/min)

G3b Moderately to severely decreased (30-44 ml/min)

G4 Severely decreased (15-29 ml/min)

G5 Kidney failure (less than 15)

Time for dialysis or transplantation

G = glomerular filtration rate

Although this staging was not available in the 1980s, I received many referrals for nutritional counseling to delay the inevitability of kidney failure. Often patients were successful in delaying dialysis 7 to 10 years. These patients were motivated to do “whatever it takes” to stay off dialysis.

I found the most enlightening thing to do was to take a patient and family to visit a hemodialysis clinic. They were more apt to follow the strict restrictions of a “diet” after viewing the alternative.

Beginning in Stage 3 CKD, it may be possible to delay the progression of the disease by decreasing protein to the normal range of 0.8 grams per kilo per day. People in the U.S. eat much more protein than they need. Good blood pressure control and good blood sugar control, if the patient is diabetic, may also help slow the progression of kidney disease. People with Stage 3 CKD should avoid dairy products, salt, processed foods, and “fast food.” A renal dietitian needs to guide them.

Table 1

Today, nephrologists are encouraged to refer patients to renal dietitians for counseling sessions no later than Stage 3. Medicare can reimburse this counseling. It saves the government money, plain and simple, as it costs Medicare $80,000 to $90,000 a year to pay for in-center hemodialysis.

Dialysis modality options

Once a patient has Stage 3-4 kidney disease, it’s time to start thinking about dialysis (or a preemptive transplant). Every individual referred to dialysis should be presented with all the modality options, including conservative care. This involves avoiding dialysis and managing the kidney disease through diet and/or palliative care. Death may be inevitable.

Here is a look at different modality options and the impact on the renal diet.

In-center hemodialysis. The majority of people in the United States with end-stage renal disease are on in-center hemodialysis. The diet is difficult to follow, with restrictions on potassium, sodium, and phosphorus. Emphasis is on controlling sodium and fluid, but restricting liquids in the diet to four cups a day is not pleasant. Patients need to avoid dairy, salt, and processed foods. At the same time they need to eat enough protein (1.2 grams per kilo per day) to make up for the losses during hemodialysis. Patients need the renal dietitian to guide them.

Peritoneal dialysis (PD).This includes continuous ambulatory peritoneal dialysis (CAPD) done during the day and continuous cycling peritoneal dialysis (CCPD) done at night. In my clinics, about 25% of the patients are on PD.

Because the patient is getting daily dialysis, the diet on PD is easier to follow with less fluid restriction. Potassium is usually not restricted; in fact patients actually need to eat more protein than usual (1.3 grams per kilo per day). This compensates for the protein that is lost during daily PD. Most of my patients remain in their jobs. Traveling is easy.

Nocturnal dialysis.This is hemodialysis done at home at night while the patient sleeps. It is done 6 or 7 nights a week, from 5 to 12 hours per session with 8 hours being the average (about 35 hours a week). The patient will need a partner trained to help them with this therapy. Patients report feeling more energetic, having better appetites, and generally have fewer complaints all around. Many patients find that the need for blood pressure medications and phosphate binders either stops or substantially diminishes. Anemia is less of a problem. Diets can be essentially normal, with few restrictions.

There are some in-center hemodialysis clinics that may provide nocturnal dialysis to the patients three times a week for eight hours. This may allow patients to continue working or attending school during the day.

Home hemodialysis (short daily or conventional).There are about 5,000 dialysis clinics in the United States, and about 14% train people to do home hemodialysis. This could be short daily hemodialysis for about 2 hours (12-14 hours a week) or performing conventional hemodialysis at home with 3 treatments at 4 hours each for a total of 12 hours a week. Like nocturnal, the frequency of short daily dialysis helps to mimic the natural kidney, so fluid management is easier and patients feel better. But the amount of dialysis is about the same as in-center dialysis, and so the diet still has restrictions. Patient may still need blood pressure medications and phosphate binders.

Conclusion

Dialysis cannot replace healthy kidneys. There are several modalities from which to choose. Each has benefits and/or drawbacks. Ultimately, the more dialysis a patient gets, the more liberal they can be with their diet. -by Peggy Harum, RD, LDN

Acknowledgement: the author would like to thank Lesley McPhatter, MS, RD, CSR, of Lynchburg (Va.) Nephrology, for assistance with this article.