Medical Nutrition Therapy for Chronic Kidney Disease
Manual of Clinical Nutrition Management G- 8 Copyright © 20 13 Compass Group, Inc.
Kidney Foundation has published diagnostic criteria and management strategies for acute kidney injury,
which replaces the term acute renal failure. Nutrition intervention strategies for acute kidney injury are
described in Table G-3 of this section and in Section III: Nutrition Management of Acute Kidney Injury and
Chronic Kidney Disease.
RRTs
The three primary types of RRTs are hemodialysis, peritoneal dialysis, and continuous RRT (2,3).
Hemodialysis: Hemodialysis accounts for 80% of all RRTs used to manage the complications of renal disease
(3). Hemodialysis uses an artificial kidney (hemodialyzer) to cleanse the blood. This process returns the body
to a more normal state by removing excess fluid and waste products. However, it does not replace the
endocrine functions of the kidney. The average treatment lasts 3 to 5 hours and is performed three times a
week. Treatment is based on adequate urea clearance to equal a urea reduction goal of greater than 65% or a
Kt/V (clearance of the dialyzer time/volume) of greater than 1.2 (2,3). Hemodialysis removes some water-
soluble vitamins such as vitamin C, folic acid, and pyridoxine. Hemodialysis also removes certain minerals
and electrolytes. Potassium is efficiently removed by hemodialysis, while phosphorus and magnesium are
removed to a lesser degree (3). Hemodialysis may increase energy requirements because of lymphocyte
stimulation and complement activation (3). Hemodialysis can be performed at a dialysis center or at home.
There are two types of more frequent hemodialysis, short daily dialysis and nocturnal dialysis. These types of
hemodialysis provide more treatment time with fewer side effects and risks; patients who receive more
frequent hemodialysis may consume a more liberal diet than patients who receive thrice weekly conventional
hemodialysis (2).
Peritoneal dialysis: This type of dialysis involves the removal of waste products and water within the
peritoneal cavity by using the peritoneal membrane as a filter. The dialysis solution (dialysate) is instilled
through the peritoneal catheter into the peritoneal cavity or peritoneum. The many blood vessels and
capillaries throughout the peritoneum are separated from the peritoneal cavity by a layer of mesothelium.
Passive movement from the peritoneal capillaries into the dialysate removes the uremic toxins. The high
osmolality of the dialysate due to the high dextrose concentration results in the removal of extracellular fluid.
This type of RRT may place the patient at increased risk for infection (eg, peritonitis) and hyperglycemia (3).
There are two major types of peritoneal dialysis:
Continuous ambulatory peritoneal dialysis (CAPD) is a manual dialysis process, whereby a continuous
presence of a dialysate in the peritoneal cavity is interrupted intermittently for drainage and instillation
of fresh dialysate. The dialysate is usually exchanged four times a day, with only a 30- to 35-minute
interruption of daily activity during each exchange. The dialysate remains in the peritoneal cavity for
3½ to 4 hours during the day and 8 to 10 hours at night.
Continuous cyclic peritoneal dialysis (CCPD) or automated peritoneal dialysis provides more daytime
freedom and a decreased risk of infection by decreasing the number of catheter connections to two per
day. A cycler machine delivers three or four dialysate exchanges each night, lasting 2½ to 3 hours each.
Approximately 2 L of dialysate remains in the peritoneal cavity during the day for 12 to 15 hours and is
then drained when the patient begins the nightly routine.
Intermittent peritoneal dialysis is also available; however, it is not a standard treatment.
Patients who receive peritoneal dialysis may develop hypokalemia, since commercially available solutions
do not contain potassium (3). Potassium can be liberalized in the diet or supplemented orally if needed. The
peritoneal dialysate can provide a substantial amount of energy from glucose to the patient when hypertonic
solutions are needed for increased fluid removal (3). Diabetic patients may have a greater risk for
hyperglycemia, and all patients can develop hypertriglyceridemia. A low-sodium, fluid-restricted diet can
help eliminate the need for higher dextrose concentration solutions. The amount of total energy absorbed
depends on the infusion volume, dwell time, and dextrose concentration (3). (See Determination of Glucose
Absorption in Peritoneal Dialysis later in this section.) The nutritional intake of patients who receive
peritoneal dialysis may be affected by bloating, abdominal fullness, and loss of appetite due to the indwelling
dialysate (3,4). The protein needs of patients who receive peritoneal dialysis are increased, and it is important
to encourage a high-protein diet to minimize the risks of malnutrition and infection. Some patients may
require protein or protein-energy supplementation to meet their daily estimated protein needs of 1.2 to 1.3
g/kg (2).
Continuous RRT: Continuous RRTs include continuous venovenous hemofiltration, continuous venovenous
hemodialysis, continuous hemodiafiltration, and slow continuous ultrafiltration (3). Each method uses a