Importance of the monthly biochemical evaluation to identify patients on hemodialysis with malnutrition.

Background: Malnutrition is a frequent complication in patients on hemodialysis and early diagnosis is important to reduce the morbidity and mortality of treatment.

Objective: To investigate the usefulness of biochemical tests performed monthly in order to identify hemodialysis patients with malnutrition.

Methods: The nutritional status of 252 patients was evaluated by objective and subjective global assessment, and the patients classified as malnourished and not malnourished. Then, during 4 consecutive months, serum creatinine, phosphorus, urea pre-and post-dialysis and Kt/V were recorded for calculation of averages. After analysis of these variables by the ROC curve we calculated the sensitivity and specificity of these parameters to identify patients with malnutrition.

Results: In ROC curve, the area under the curve for urea was 0.683, 0.71 for phosphorus, 0.724 for Kt/V and 0.765 for creatinine. For values of urea ≤ 90 mg/dL, phosphorus ≤ 4.2 mg/dL, Kt/V ≥ 1.6 and creatinine ≤ 6.5 mg/dL, the specificity ranged between 80% and 88% and sensitivity between 26% and 51%. The negative predictive value ranged between 90% and 92% and positive predictive value between 23% and 32%. The association of two or more of these índices did not change significantly these values.

Conclusions: Our results suggest that serum urea ≤ 90 mg/dL, creatinine ≤ 6.5 mg/dL, phosphorus ≤ 4.2 mg/dL, and Kt/V ≥ 1.6 can be used for screening patients with malnutrition. However, using these cutoffs the parameters tend to overestimate the number of patients with malnutrition.