Nutrition plays an important role in the management of patient outcomes during all stages of chronic kidney disease (CKD) as well as throughout the transplant process.
Nutrition needs vary across three phases of transplantation: pretransplant, acute posttransplant, and long-term/maintenance posttransplant.
Ongoing reassessment of nutrition status is essential for identifying nutrition goals and their efficacy as well as prioritizing nutrition needs during each phase of transplantation.
Nutrition intervention has been useful in attenuating consequences of comorbid conditions and medication side effects and may contribute to improved kidney transplant outcomes.
The U.S. Department of Health and Human Services (DHHS) and Centers for Medicare & Medicaid Services (CMS) mandate that a transplant center provides nutrition assessments and diet counseling services furnished by a qualified dietitian to all transplant patients and living donors (Electronic Code of Federal Regulation §482.94[e]).
Comorbidities associated with CKD and dialysis, particularly coronary heart disease, metabolic bone disease, and malnutrition, may affect transplant candidacy.1
Nutrition intervention and optimization of nutrition status should be addressed as part of the evaluation process prior to transplantation.
The goal of pretransplant nutrition management is to optimize nutrition status to achieve or maintain appropriate calorie and protein intake to attenuate the catabolic effects and metabolic abnormalities associated with CKD in order to optimize long-term success of the transplant.
Nutrition assessment of the pretransplant candidate should address areas of nutrition risk including malnutrition, obesity, bone disease, metabolic parameters, and gastrointestinal (GI) issues (see Table 17-1 for components considered in nutrition assessment).2,3
Individuals requiring dialysis and those with stages 4 to 5 CKD bring a wide-ranging history of nutrition management—from no knowledge of appropriate nutrition modification to many years of medical nutrition therapy/intervention provided by an advanced practice renal dietitian.
TABLE 17-1 Components of Nutrition Assessment for Transplant Candidates
Obesity has been identified as a risk factor for a number of chronic health conditions including cardiovascular disease (CVD), diabetes, hypertension, and kidney disease.4
Obesity is defined as body weight/fat that is above what is considered healthy for a given height or excess adiposity.
Body mass index (BMI) is typically used as a screening tool to identify obesity but is not diagnostic (Table 17-2).
TABLE 17-2 Centers for Disease Control and Prevention Body Mass Index Classification
Body mass index (kg/m2)
Class 1 obesity
Class 2 obesity
40 or higher
Class 3 obesity
Limitations of using BMI to define obesity
BMI does not allow for variations in body habitus, specifically fat distribution and musculature.
The inability to distinguish lean body mass from fat mass may lead to misclassification. Therefore, other factors including weight distribution, physical fitness, and cardiac risk factors should also be considered.
Prevalence of obesity has increased in the dialysis population (the majority of those being evaluated for kidney transplant) in step with the general population.
Clinical impact of obesity on outcomes
The “obesity paradox” refers to the counterintuitive finding that there is a survival benefit with increasing BMI in dialysis patients.
Although it has been thought that higher levels of obesity are associated with worse posttransplant outcomes, comparing the survival benefit of obese individuals on dialysis to obese kidney transplant recipients, the benefit favoring transplantation over dialysis is similar to the benefit seen with the nonobese population.5,6
However, obesity is correlated with posttransplant risk factors, including wound infection/dehiscence, incisional hernia, increase operation duration, new onset diabetes, increased length of hospital stay, delayed graft function (DGF), and hypertension.6,7 Therefore, transplant candidates with obesity should be fully informed of these risks and should be counseled on lifestyle, diet modifications, and consideration for bariatric surgery for weight management.
BMI threshold for transplantation
In general, there is no specific BMI threshold for transplantation. However, BMI threshold may be set by each transplant program.
Transplant eligibility for those with BMI >40 kg/m2 may be individually considered.
Note: Bariatric surgery has been deemed safe in the dialysis population and may be reasonable alternative for some individuals in preparation for transplantation.8,9 Care should be taken in choosing a surgical procedure because changes to the gut anatomy may result in malabsorption and alter pharmacokinetics (also discussed in chapter 4). Posttransplant immunosuppression levels will require close monitoring.
Optimizing nutrition and functional status should be addressed when preparing patients for transplantation.
Diagnostic indicators of malnutrition
Although albumin levels may be used as a prognostic indicator for morbidity and mortality in the chronic dialysis population, it may be an unreliable marker for malnutrition because albumin levels are sensitive to acute and chronic physiologic responses to disease and injury.
It has been proposed that a combination of several clinical, nutrition, and biochemical parameters (eg, laboratory values, body mass, muscle mass, dietary intake, nutritional scoring systems) be considered when specifically identifying protein-energy wasting in CKD or dialysis patients.2,10
In 2012, the Academy of Nutrition and Dietetics (AND) and the American Society of Parenteral and Enteral Nutrition (ASPEN) established four clinical characteristics (energy intake, weight loss, physical findings, and functional status) to assess for identification and documentation of adult malnutrition.11
Functional status measured by grip strength is one of the criteria/characteristics considered by AND/ASPEN in the diagnosis of malnutrition. Poor functional status or “frailty,” although grouped with the International Classification of Diseases,
10th revision (ICD10) code R54 as “age-related physical disability,” may be seen in individuals of any age and is a risk factor for poor kidney transplant outcomes.12
Clinical impact of malnutrition and poor functional status on outcomes
Pretransplant malnutrition has been identified as a factor associated with adverse kidney transplant outcomes.13
Extreme levels of BMI (both underweight and morbid obesity) have been observed to negatively affect transplant outcomes. Increased mortality and death-censored graft loss have been associated with underweight individuals (BMI <18.5 kg/m2).14
Increased length of hospital stay, early hospital readmissions following transplantation, DGF, and mortality have been associated with patients who experience reduced physical ability, decreased muscle mass, weakness, and weight loss pretransplant.15
Any condition that interferes with ingesting and absorbing adequate nutrition such as gastroparesis or malabsorption should be fully investigated because this could interfere with achieving adequate levels of immunosuppression posttransplant.
Pretransplant bone disease associated with CKD (eg, renal osteodystrophy, adynamic bone, or mix-bone disease) may exacerbate the risk for posttransplant bone disease (PTBD) and fracture associated with prednisone and calcineurin inhibitor use.
CKD-associated bone mineral disorders should be managed well in the pretransplant period to preserve both bone and cardiovascular health to optimize transplant outcomes.
The 2017 updated Kidney Disease Outcomes Quality Initiative (KDOQI) guidelines recommend restricting dietary phosphorus to maintain appropriate serum phosphorous levels.16,17
Achieving this level of restriction may be difficult, especially for dialysis patients with higher protein needs, because higher protein foods tend to also contain higher levels of phosphorus. Bioavailability of phosphorous sources should be considered.
Referral to renal nutrition specialist/dietitian is recommended.
Assessing patient’s adherence to dietary modifications, compliance with phosphate binders with meals and interdialytic fluid restrictions, and complete dialysis treatments may help anticipate the likelihood of success posttransplant.
Reviewing trends in the patient’s nephrology or dialysis records (eg, laboratory data, blood pressure records, interdialytic weight gains) and hospital admissions may provide valuable information regarding adherence.
Adherence to medical regimens pretransplant may predict adherence in the posttransplant setting.
Nutrition goals during the early posttransplant phase
Maintain protein balance and desirable body weight.
Mitigate nonimmunologic adverse effects of immunosuppressive medications.
Nutrient requirements are increased during the immediate posttransplant period due to surgical stresses, medication side effects, and wound healing. Fluid, electrolytes, and micronutrients may require modification based on graft function and laboratory values (Table 17-3).2,3
Clinical judgment and expertise of the nutrition care specialist is needed when assessing nutrition needs of the individual patient.
Nutrient needs are generally calculated using the patient’s actual dry body weight.
There is an increase in protein catabolic rate (PCR) related to postoperative stress and the typically large doses of corticosteroids administered perioperatively. The rise in PCR generally lasts through postoperative week 3 and may be seen again during treatment periods for rejection.
Recommendations for initial protein intake: 1.3 to 2.0 g/kg body weight
Energy requirements during the early period posttransplant may be calculated using 30 to 35 kcal/kg body weight or 1.3 to 1.5 times basal energy expenditure (BEE) using the Harris-Benedict equation.
The lower end of the calorie range is targeted for obese patients, whereas underweight patients require higher calories at the upper end of the range.
TABLE 17-3 Daily Nutrient Requirements/Recommendations Posttransplant
Early period (≤6-8 wk)
30-35 kcal/kg body weight or 1.3-.15 × BEE
Goal to attain/maintain desirable body weight
1.3-2 g/kg body weight
0.8-1 g/kg body weight (Limit to 0.6-0.9 g/kg with chronic graft dysfunction.)
50%-60% of total calories
Complex carbohydrate sources and limit simple sugars for good glycemic control
25%-35% total calories
<35% total kcal/limit saturated and trans fats
Individualize based on allograft function For delayed graft function, ˜500-750 mL + urine output
Goal to maintain adequate hydration
Individualize; typically 2-4 g/d
Individualize; if hypertensive, limit to 2 g/d.
Individualize; typically 2-4 g/d
Individualize; if hyperkalemic, limit to 2-4 g/d.
Individualize based on graft function; often may need to supplement
Individualize based on graft function; may need to limit/supplement
Oral supplements for <1.5 mg/dL Intravenous supplementation for <1.2 mg/dL
Supplement as needed
Recommended intravenous supplementation % saturation <30% and ferritin <500 mg/dL
Supplement as needed
Abbreviation: BEE, basal energy expenditure using Harris-Benedict equation.
Posttransplant glucose intolerance/diabetes may be related to immunosuppression, surgical stress, obesity, age, infection, and/or family history.
Recommendations for carbohydrate intake: Limit dietary ingestion of simple carbohydrates, with the majority of carbohydrates from complex sources comprising 50% to 60% of total calories.
Carbohydrate-controlled diet education by a registered dietitian in addition to medical management is recommended for patients with continued hyperglycemia.
Patients who require dietary modification or oral hypoglycemic agents to manage their diabetes pretransplant will likely require insulin posttransplant.
The role of fat in the early postoperative period is to aid in providing the remainder of calories needed that are not provided by protein and carbohydrate, targeting approximately 25% to 35% of calorie intake from fat per the National Heart, Lung, and Blood Institute Lifestyle Interventions to Reduce Cardiovascular Risk and Managing Blood Cholesterol in Adults 2013 guidelines.
Fluid needs vary postoperatively based on kidney allograft function.
Fluid administration should match increasing urine output to avoid net negative fluid balance and hypotension.
In recipients who have reached a euvolemic state postsurgery, a fluid intake of approximately 2,000 mL is generally adequate.
In recipients with DGF, a modification would be indicated (eg, volume of urine output plus an additional 500 to 750 mL to account for insensible losses).
In general, normotensive kidney transplant recipients’ sodium intake should be moderate and not to exceed 3 to 4 g/d, as part of a heart healthy lifestyle.
For individuals experiencing DGF, volume overload, or hypertension, limiting sodium intake to 2 g/d is reasonable.
An increase in sodium intake may be recommended for hypotensive patients.
Potassium (also discussed in chapter 10)