Nutrition Support in Hemodialysis and Peritoneal Dialysis

Abstract

Protein-energy wasting (PEW) is common among patients undergoing maintenance dialysis, and many signs of PEW can be improved with nutrition support therapy. Early and regular nutrition counseling by registered dietitian (or international equivalent) is essential for the prevention and treatment of PEW in maintenance dialysis patients. When nutrition counseling alone is unable to bridge the gap between protein-energy intake and the target requirements, oral nutritional supplements (ONS) should be prescribed to improve nutritional status. When maintenance dialysis patients with PEW are unable to meet protein and energy requirements with nutrition counseling and ONS, enteral tube feeding should be considered. Intradialytic parenteral nutrition (IDPN) should only be used as supplemental nutrition in hemodialysis patients with PEW, and adequate spontaneous protein and energy intakes are required to compensate for the difference between those provided by IDPN and the target requirements. Intradialytic amino acid therapy remains a viable option for protein-energy wasted peritoneal dialysis patients with insufficient dietary intake, as well as those with tolerance, compliance, and suitability issues of oral intake and other forms of enteral supplementation.

Case Study

A 51-year-old Caucasian man (Mr. Smith) with a medical history of stage 5 CKD secondary to hypertension and glomerulonephritis presents with progressive decline of kidney function, poor appetite, nausea, lethargy, and decreased urine output. His nutritional assessment parameters are as follows: height = 170 cm; weight = 75.6 kg; BMI = 26.2 kg/m²; 5% unintentional weight loss over the past 3 months; SGA score = 4; serum albumin = 3.4 g/dL; and pedal edema. Peritoneal dialysis is started with the aim of removing excess fluid and uremic toxins, as well as improving nutritional status.

At 3 months after initiating peritoneal dialysis, Mr. Smith is feeling better. His pedal edema is resolving. His uremic symptoms, appetite, and oral intake are improving. His nutritional assessment parameters are as follows: dry body weight = 73.6 kg; BMI = 25.5 kg/m²; serum albumin = 4.0 g/dL; and SGA score = 6. Upon physical examination, Mr. Smith is euvolemic. His total intakes of protein and energy including the calories provided by the peritoneal dialysate are 1.3 g protein/kg/day and 33 kcal/kg/day, respectively.

Having been treated with peritoneal dialysis for 3 years, Mr. Smith is admitted to hospital due to turbid peritoneal effluent accompanied by constant abdominal pain. He had two prior episodes of peritonitis in the past few years. The laboratory findings and bacterial culture of the peritoneal dialysate confirm PD-associated peritonitis. At the same time, Mr. Smith experiences nausea, poor appetite, and reduced food intake. His food record chart indicates an ingestion of approximately 0.6 g protein/kg/day and 24 kcal/kg/day on the first few days of hospital admission.

Mr. Smith is given a 2-week course of intraperitoneal antibiotics upon diagnosis of peritonitis. He is also prescribed a trial of renal-specific ONS, providing an additional 25 g protein and 500 kcal daily. With the completion of the antibiotic therapy and the resolution of the peritonitis, improvements in appetite and oral intake are observed. He is subsequently discharged from the hospital. Upon hospital discharge, his estimated total protein and energy intakes including the use of ONS are 1.2 g/kg/day and 32 kcal/kg/day, respectively. His nutritional assessment parameters are as follows: dry weight = 71.5 kg; BMI = 24.7 kg/m²; 6% unintentional weight loss over the past 3 months; serum albumin = 3.4 g/dL; and SGA score = 4. In view of recurrent peritonitis, his renal replacement therapy is changed from peritoneal dialysis to hemodialysis.

At 2–3 months after transition to hemodialysis, his nutritional parameters are as follows: dry weight = 76.1 kg; BMI = 26.3 kg/m²; serum albumin = 4.1 g/dL; and SGA score = 6. Upon physical examination, he is euvolemic. His food diary shows an estimated consumption of 1.2 g protein/kg/day and 33 kcal/kg/day excluding the use of ONS.

Over the course of the next few years, he is relatively stable, and receives regular nutrition counseling from a registered dietitian. He is compliant with his hemodialysis regimen and manages to maintain nutritional assessment parameters within acceptable ranges. After 3–4 years on hemodialysis, Mr. Smith is admitted to hospital for 3 weeks with pneumonia. His nutritional assessment parameters immediately post-discharge are as follows: dry weight = 68.8 kg; BMI = 23.8 kg/m²; 9% unintentional weight loss over the past 2 months; temporal wasting indicated by physical examination; serum albumin = 3.2 g/dL; and SGA score = 4. His diet history indicates a spontaneous dietary intake of 0.9 g protein/kg/day and 25 kcal/kg/day.

Over the course of the next 3 months, there is no improvement in Mr. Smith’s nutritional assessment parameters. His nutritional status continues to decline despite liberalization of his diet and the use of ONS. His nutritional assessment parameters are as follows: dry weight = 64.2 kg; BMI = 22.2 kg/m²; unintentional weight loss of 7% over the past 3 months; muscle and fat wasting upon physical examination; serum albumin = 3.1 g/dL; and SGA score = 2. His diet history shows a consumption of 0.7 g protein/kg/day and 19 kcal/kg/day.

Although enteral tube feeding is proposed to Mr. Smith, he is very reluctant to attempt the suggested feeding methods including nasogastric tube feeding and percutaneous endoscopic gastrostomy feeding. With Mr. Smith’s agreement, the multidisciplinary team decides to commence IDPN. At 5 months after starting IDPN, there is only marginal improvement in Mr. Smith’s nutritional assessment parameters, and no improvement is observed for spontaneous dietary protein and energy intakes. IDPN is subsequently discontinued. After further discussion with Mr. Smith, he eventually consents to initiate enteral nutrition via nasogastric tube feeding. Subsequently, there are progressive improvements in spontaneous dietary protein and energy intakes, as well as various nutritional assessment parameters.

Case Questions and Answers

• 1. Is Mr. Smith presented with PEW upon initiation of peritoneal dialysis?

• Answer: Yes, PEW can emerge in early CKD, and the risk of PEW increases as CKD progresses. Mr. Smith displays signs of PEW including poor appetite, nausea, 5% weight loss over the past 3 months, moderate PEW on SGA, and mild hypoalbuminemia.

• 2. Compared to nondialysis-dependent CKD, what are the specific concerns with the recommendations for dietary protein and energy intakes in maintenance peritoneal dialysis?

• Answer: Compared to nondialysis-dependent CKD, higher protein and energy intakes are recommended by current evidence-based practice guidelines and expert consensus statement, that is, 1.0–1.5 g protein/kg BW/day and 25–35 kcal/kg BW/day. Every effort should be made to remove any unnecessary dietary restrictions. Education on calorie-dense foods and high biological value protein is necessary, as well as ways to improve oral intake.

• 3. After initiating peritoneal dialysis, should Mr. Smith aim for a dietary energy intake of 25–35 kcal/kg BW/day?

• Answer: No, Mr. Smith absorbs calories from glucose in the dialysate, and the calories provided by the peritoneal dialysate should be subtracted from 25 to 35 kcal/kg BW/day to derive the target dietary energy intake.

• 4. Is Mr. Smith presented with PEW at 3 months after the initiation of peritoneal dialysis?

• Answer: Mr. Smith has no obvious signs of PEW at 3 months after the initiation of peritoneal dialysis. His total protein and energy intakes are within the target requirement ranges, alongside improvements in appetite and oral intake. Although a reduction in body weight is observed, it is likely a resolution of volume overload reflected by euvolemia upon physical examination. Mr. Smith is no longer hypoalbuminemic, and his SGA score is not suggestive of PEW.

• 5. On the first day of his peritonitis-associated hospital admission, he was prescribed a renal menu (i.e., a menu that is protein-energy dense and low in electrolytes). Is this menu adequate as a form of nutrition support therapy? If not, what should be the next appropriate step of nutrition support and how would you optimize the outcome?

• Answer: No, the prescription of a renal menu is insufficient to meet both protein and energy requirements. This is indicated by low protein and energy intakes on the food record chart, alongside reported symptoms of nausea, poor appetite, and reduced food intake. A full nutritional assessment is required, and the use of ONS should be considered as the next appropriate step. ONS should be prescribed based on the patient’s requirements, preference, compliance, and tolerance, as these are important success factors.

• 6. After his recovery from peritonitis, should he be discharged from the hospital with an ONS prescription?

• Answer: Yes, although Mr. Smith is meeting both protein and energy requirements, it is derived from both oral diet and the use of ONS. An oral diet alone remains insufficient to attain the requirements. Mr. Smith is displaying signs of PEW including 6% unintentional weight loss over the past 3 months, hypoalbuminemia, and moderate PEW on SGA. Regular nutritional assessment and continuous dietary counseling are essential after the initiation of hemodialysis.

• 7. Should the use of ONS be discontinued at 2–3 months after transition to hemodialysis?

• Answer: Yes, the use of ONS should be discontinued, because his nutritional status has improved with no obvious signs of PEW. He is attaining both protein and energy targets without the use of ONS.

• 8. Mr. Smith was prescribed a trial of renal-specific ONS during the episode of pneumonia-associated hospitalization. Should he continue to take the ONS after hospital discharge?

• Answer: Yes, ONS should be continued upon hospital discharge, because Mr. Smith is displaying signs of PEW including unintentional weight loss, temporal wasting on physical examination, moderate PEW on SGA, and hypoalbuminemia. His spontaneous dietary protein and energy intakes are insufficient to meet protein and energy requirements, but both intakes are higher than the required minimum for ONS to be effective (e.g., 20–24 kcal/kg/day and 0.8–1.0 g protein/kg/day). Regular monitoring and intensive nutrition counseling are critical during the supplementation period. Implementing changes to the ONS prescription may be necessary to improve Mr. Smith’s adherence and hence the overall effectiveness of ONS.

• 9. Despite liberalization of his diet and the use of ONS, his nutritional status continues to decline. Is Mr. Smith an ideal candidate for enteral tube feeding ?

• Answer: Yes, Mr. Smith is an ideal candidate for enteral tube feeding . He is exhibiting severe PEW on SGA, hypoalbuminemia, and unintentional weight loss of 7% over the past 3 months. His spontaneous dietary protein and energy intakes are <0.8 g/kg/day and <20 kcal/kg/day. Continuation of ONS and nutrition counseling are unlikely to achieve the recommended dietary protein and energy requirements. Daily nutrition support is important for Mr. Smith, and enteral nutrition should always be preferable to parenteral nutrition as feeding through the gastrointestinal tract helps to maintain its normal structure and function.

• 10. Should IDPN be discontinued after a trial period of 5 months?

• Answer: Yes, most maintenance hemodialysis patients respond to IDPN after 3–6 months of therapy. Lack of improvement after 3–6 months should render a decision to discontinue.