Olfactory function in patients undergoing hemodialysis as assessed by Sniffin' Sticks testing

OBJECTIVE: This study evaluated olfactory function in patients undergoing hemodialysis. The evaluation utilized the Sniffin' Sticks test. PATIENTS AND METHODS: The study enrolled 56 individuals undergoing hemodialysis for chronic renal failure alongside 54 healthy controls. The Sniffin' Sticks battery was used to assess olfactory function in all subjects. The battery included 12 separately identifiable odors. A score below 6 was considered anosmia, whilst scores ranging from 7 to 10 were classed as hyposmia. A score of at least 11 indicated normal olfaction. RESULTS: There was a statistically significant difference in scores between the two groups. The hemodialysis patients scored 9.12 +/- 2.77 compared to 10.72 +/- 1.94 in the controls. In the hemodialysis patients, scores for males and females did not differ significantly. Furthermore, there was no correlation between score and age, sex or length of renal failure. Some 12.5% of hemodialysis patients were anosmic, whilst 50% were hyposmic. The corresponding rates in the control group were 7.4% and 20.4%. CONCLUSIONS: Undergoing hemodialysis is associated with a decreased total score on the Sniffin' Sticks battery, with anosmia in 12.5% of patients and hyposmia in 50.0%. Thus, olfactory impairment is present in 62.5% of hemodialysis patients. According to previous research, renal transplantation results in an improved ability to smell, depending on how plastic the neurons involved in olfaction are.