Relationship of impaired olfactory function in ESRD to malnutrition and retained uremic molecules.

Background Olfactory function is impaired in patients with end-stage renal disease (ESRD) and may contribute to uremic anorexia. Only limited correlations of olfactory function and nutritional status were reported. This study examines the relationship of impaired olfactory function to malnutrition and levels of the retained uremic solutes monomethylamine, ethylamine, indoxyl sulfate, and P-cresol sulfate. Study Design Cross-sectional observational study. Setting & Participants 31 stable maintenance hemodialysis patients from an urban outpatient dialysis unit and 18 people with normal renal function participated. Predictor Nutritional status assigned by using Subjective Global Assessment (SGA) score; SGA score of 7 indicates normal nutritional status; SGA score of 5 to 6, mild malnutrition; and SGA score of 3 to 4, moderate malnutrition. Outcomes & Measurements The primary outcome is olfactory function, assessed using the University of Pennsylvania Smell Identification Test. Levels of retained uremic solutes were measured from a predialysis serum sample. Demographic data and laboratory values for nutritional status, adequacy of dialysis, and inflammation were collected. Results Mean smell scores were 34.9 ± 1.4 for controls, 33.5 ± 3.3 for patients with SGA score of 7, 28.3 ± 5.8 for patients with SGA score of 5 to 6, and 27.9 ± 4.4 for patients with SGA score of 3 to 4 ( P P = 0.02) and higher C-reactive protein levels ( P = 0.02). Neither smell score nor nutritional status was associated with levels of retained uremic solutes. Limitations Small sample size, only cross-sectional associations can be described. Conclusions Our results suggest an association between poor nutritional status and impaired olfactory function in patients with ESRD. Additional research is needed to discover the uremic toxins mediating these processes.