- Click here for explanation of classification scheme.

To review the evidence documenting the interrelationship between nutritional status and clinical outcome in the renal patient population.

Studies including patients with chronic, progressive renal disease and dialysis patients.

Not mentioned.

Recruitment

Methods of study inclusion not described.

Design

Narrative Review.

Blinding Used (if applicable):  not applicable.

Intervention (if applicable):

Assessment of nutritional health for renal patients, both chronic kidney disease (CKD) and dialysis.  Outcomes include recognizing valid indices and using Subjective Global Assessment (SGA) method, recognizing and treating "undernutrition" and setting clinical goals and the history of nutrition supplementation and evaluating specific nutritional methods of intervention.

Statistical Analysis:

Statistical analysis not performed.

Timing of Measurements

Not applicable.

Dependent Variables

1. Nutrition Assessment:  Listing of anthropometric, biochemical and diet intake methods considered by the authors to be recognized as valid for renal patients, taking into account metabolic abnormalities that accompany renal disease.  The pros and cons of assessment using various serum proteins (transferrin, prealbumin, albumin and insulin-like growth factor-1) are discussed.  SGA is discussed, having been validated for the peritoneal dialysis patient population in 1991.
2. Undernutrition:  Some correlations noted from the Modification of Diet in Renal Disease (MDRD) Study are mentioned, particularly the correlation between GFR, diet intake, and indices of nutritional status.  Authors list factors contributing to malnutrition in this population:  anorexia, metabolic acidosis, endocrine disorders, comorbidities, reduced intake, dialysis related, and psychosocial.
3. The historical use of diet manipulation, use of parenteral glucose, early use of tube feedings, introduction of oral essential amino and keto acids, nutrition problems associated with hemodialysis, total parenteral nutrition evolving into IDPN (TPN administered into venous drip chamber during HD), and types of enteral nutrition products available are narratively mentioned.

Independent Variables

Control Variables

Initial N:  There are 83 articles referenced in this review.

Attrition (Final N):  83

Age:  not mentioned

Ethnicity:  not mentioned

Other relevant demographics:

Anthropometrics:

Location:  Worldwide studies

Nutrition assessment of the renal patient

1. Serum proteins

a. transferrin, prealbumin and albumin are all affected by hydration status.

b. transferrin is affected by iron status, in iron deficiency, transferrin is artificially elevated and artificially decreased with iron overload. For the patient receiving EPO therapy and iron supplementation, the use of transferrin for nutrition assessment is not appropriate unless the patient is on a stable regimen with adequate iron replacement.

c. prealbumin levels may be deceptively elevated in the euvolemic patient with CRF because this protein is associated with kidney function. Dialysis patients often have falsely elevated levels since the kidney is the organ of catabolism for prealbumin. In spite of limitations, prealbumin is useful in patients with stable kidney function.

d. albumin has a long half-life (18-20 days) and is slow to change in response to nutrition intervention.  Also, albumin is a negative acute phase reactive protein, synthesis is suppressed by inflammation.

e. Insulin-like growth factor (IGF-1) appears to be a sensitive biochemical indicator of nitrogen balance but IGF-1 is not a lab routinely done.

2. Subjective global assessment (SGA)

a. SGA requires evaluating subjective and objective patient information including medical history and physical exam.

b. after completion of the evaluation, patients are assigned to one of 3 groups: A: well-nourished, B: mild to moderate malnutrition or C: severe malnutrition.

c. work continues to validate SGA for predialysis and HD patients.

Undernutrition of the CRF patient

1. The largest set of data concerning the nutritional status of the patient with CRF is from the MDRD study.  There were correlations between GFR, diet intake and indices of nutritional status (serum albumin, transferrin and body weight) with the earliest relationship at GFR of 35 ml/min.

2. A goal of nutrition assessment is to improve patient outcome by identifying the patient at risk for developing malnutrition and providing early intervention.

Nutrition interventions and strategies for feeding

1.  The approach to developing nutrition intervention for the renal patient requires:

a.  completing a comprehensive nutrition assessment to ascertain the degree of malnutrition

b.  obtaining an accurate diet and appetite assessment to evaluate current intake and eating habits to identify any problems related to self-feeding, access to food, and GI distress (diarrhea, vomiting, or nausea)

c.  determining if there are any active psychosocial, medical, uremia, or medicinal-related issues that are affecting food intake and indices of nutritional status.

2.  Developing strategies for intervention can be applied according to the degree of malnutrition ascertained:

a.  mild malnutrition:  diet liberalization while monitoring lab values, alter the concept and timing of meals, identifying specific food aversions or environmental stimuli that might promote or impede food intake and suggest alternatives.

b.  moderately malnourished:  diet liberalization and oral supplements, either homemade or commercial while monitoring labs

c.  severely malnourished:  evaluate for tube feedings or TPN if indicated.

Suggested approach to developing nutrition interventions and strategies for feeding:

1. complete a comprehensive nutrition assessment to ascertain degree of malnutrition.
2. obtain accurate diet and appetite assessment, identify problems related to intake.
3. determine psychosocial and medical (including dialysis or uremia) issues that may affect intake or indices of nutrition status.

Strategies for intervention can be based on degree of malnutrition and should include strategies to achieve patient adherence:

1. Mild: liberalize diet, small, frequent meals or snacks, note changes in protein requirements when changing to dialysis.
2. Moderate: include oral supplements, IDPN and intraperitoneal nutrition.
3. Severe: evaluate for tube feeding or TPN.

Future therapies under consideration include appetite stimulants, recombinant human growth hormone, and IGF-1.  Some consideration of anabolic steroids.  Need to clarify events leading to hypoalbuminemia and identify catabolic stimuli.

Industry:	Everest Health Care Services Corporation Other:
University/Hospital:	University of Michigan,

No qualitative or quantitative assessment has been reported in this review.

No parameters for assessing degree of malnutrition are defined. 

Authors' conclusion/discussion appears to be practice-based, with no data to support the conclusions or recommendations.