Methods for assessing nutritional status of patients with renal failure.

Since wasting and malnutrition are common problems in patients with renal failure, it is important to develop techniques for the longitudinal assessment of nutritional status. This paper reviews available methods for assessing the nutritional status; their possible limitations when applied to uremic patients are discussed. If carefully done, dietary intake can be estimated by recall interviews augmented with dietary diaries. Also, in a stable patient with chronic renal failure, the serum urea nitrogen (N)/creatinine ratio and the rate of urea N appearance reflect dietary protein intake. A comparison of N intake and urea N appearance will give an estimate of N balance. Anthropometric parameters such as the relationship between height and weight, thickness of subcutaneous skinfolds, and midarm muscle circumference are simple methods for evaluating body composition. Other methods for assessing body composition, such as densitometry and total body potassium, may not be readily applicable in patients with renal failure. More traditional biochemical estimates of nutritional status such as serum protein, albumin, transferrin, and selected serum complement determinations show that abnormalities are common among uremic patients. Certain anthropometric and biochemical measurements of nutritional status are abnormal in chronically uremic patients who appear to be particularly robust; thus, factors other than altered nutritional intake may lead to abnormal parameters in such patients. Serial monitoring of selected nutritional parameters in the same individual may improve the sensitivity of these measurements to detect changes. Standards for measuring nutritional status are needed for patients with renal failure so that realistic goals can be established optimal body nutriture.