Olfactory dysfunction in hemodialysis patients: baseline differences and longitudinal changes compared with healthy controls.

BACKGROUND: Olfactory dysfunction is increasingly recognized in patients with chronic kidney disease, particularly among those receiving maintenance hemodialysis (HD). Despite its potential clinical relevance for nutrition and quality of life, longitudinal data on olfactory function in HD patients remain limited. METHODS: This prospective observational study included 100 patients undergoing maintenance HD and 52 healthy controls. Olfactory function was assessed using the identification component of the Sniffin' Sticks Test and expressed as the percentage of correctly identified odors. Sixty HD patients underwent repeat olfactory testing after approximately one year. Multivariable regression models were used to evaluate clinical and biochemical factors associated with baseline olfactory function and its longitudinal change. RESULTS: Baseline olfactory identification scores were significantly lower in HD patients compared with controls (60.6% vs 76.1%, P < .001). Overall, 91% of HD patients exhibited olfactory dysfunction, including 74% with hyposmia and 17% with anosmia. Higher global cognitive function scores (β = .42, P = .001) and higher serum albumin levels (β = .29, P = .015) were independently associated with better baseline olfactory performance. Baseline olfactory performance independently predicted longitudinal change (β = .012, P = .006), whereas dialysis adequacy (Kt/V) was not associated with olfactory outcomes. CONCLUSIONS: Olfactory dysfunction is highly prevalent in patients undergoing maintenance hemodialysis and is closely linked to cognitive and serum albumin levels. Longitudinal olfactory trajectories vary across individuals and did not appear to be strongly associated with dialysis adequacy in this cohort, suggesting that olfactory impairment may reflect overall disease burden rather than dialysis dose.