Quantitative estimation of dietary intake in patients on hemodialysis.

A simple method to calculate the amount of dietary (protein, sodium and potassium) intake in hemodialyzed patients was developed. In 8 nutritionally stable patients, the amount of dietary intake was monitored conventionally by a dietary record method. In contrast, assuming that the amount of dietary intake was equal to the amount of accumulation in the body, the former was calculated as the change in the product of serum concentrations and total body fluid volume, which was estimated based on the sex and body build of each patient. The urea accumulation was converted to the protein intake. The interdialytic dietary protein and sodium intake calculated by this method, 120 +/- 10 g and 240 +/- 40 mEq, respectively, was not significantly different from that obtained by the dietary record, while the interdialytic potassium accumulation, 60 +/- 7 mEq, was significantly smaller than the dietary intake, 110 +/- 9 mEq, obtained by the record method, though the correlation was significant. Thus, the amount of protein and sodium intake can be calculated simply without diet research or body fluid volume measurements. Although potassium intake can not be calculated exactly because of intestinal loss, this simple method gives us a rough estimate. In addition, multiple regression analysis showed that the amount of energy intake obtained by the record method may be explained by the protein and sodium intake estimated by simple calculation.