Amanda Raff, Sung Lieu, Michal Melamed, Zhe Quan, Manish Ponda, Timothy Meyer, Thomas Hostetter. Department of Medicine, Albert Einstein College of Medicine, Bronx, NY; Department of Medicine, Stanford University, Palo Alto, CA
Olfactory function is impaired in patients with end stage renal disease (ESRD) and may contribute to uremic anorexia. However, only limited correlations of olfactory function and nutritional status have been reported and the etiology of impaired olfactory function is unknown.
We performed a cross-sectional observational study of 31 hemodialysis patients to examine the relationship of impaired olfactory function to malnutrition and levels of the retained uremic solutes monomethylamine, ethylamine, indoxyl sulfate (indican), and P-cresol sulfate. Olfactory function was assessed with the University of Pennsylvania Smell Identification Test. The Subjective Global Assessment (SGA) was used to determine the nutritional status of the dialysis patients. Eleven patients had a normal nutritional status (SGA 7), 10 patients had mild malnutrition (SGA 5 - 6), and 10 patients had moderate malnutrition (SGA 3 - 4). Pre-dialysis serum samples were drawn to measure levels of the retained solutes. Eighteen people with normal renal function served as controls. Mean smell scores were 34.9 +/- 1.4 for controls, 33.5 +/- 3.3 for SGA 7 patients, 28.3 +/- 5.8 for SGA 5 - 6 patients, and 27.9 +/- 4.4 for SGA 3 - 4 patients. Smell scores were significantly higher for the normal controls compared to the population of ESRD patients (p < 0.001). There was no difference in mean smell score for normal controls and SGA 7 patients. However, patients with lower SGA scores had significantly lower smell scores (p = 0.015). In this small study neither smell scores nor nutritional status were associated with predialysis levels of monomethylamine, ethylamine, indican, or p-cresol sulfate in the 31 ESRD patients.
Our results confirm the finding of impaired olfactory function in ESRD patients and reveal an association between poor nutritional status and impaired olfaction. Simple tests of olfactory function may provide a useful surrogate end point during the search for the uremic toxins mediating malnutrition.
Presented at the American Society of Nephrology Renal Week 2007, San Francisco, California