Odor olfactory dysfunction in chronic kidney disease and diabetes mellitus and its association with nutritional factors.

Background: Olfactory changes connection to deteriorated quality of life in chronic kidney disease cases (CKD) and diabetes mellitus (DM). The nutritional status is altered in CKD and DM and it closely interconnected with olfactory function. We aimed to study the olfactory dysfunction in these populations.

Methods: We conducted a cross-sectional research on CKD and DM cases aged 20-50 (27 healthy controls, 77 CKD patients, and 36 DM patients). We used the Iran Smell Identification Test (Iran-SIT) version of the University of Pennsylvania Smell Identification Test (UPSIT) to evaluate the olfactory function. The significant level was set as <0.05.

Results: Our 140 cases included 51.4% of men (mean age of 46.7±10.6 years). The total score of the Iran-SIT test indicated that olfactory impairment in the CKD was higher (16.2±4.2) than in the DM (18.8±2.1) and control groups (20.4±1.2) (P=0.001). It was determined that 54.5% of CKD patients and 38.9% of the DM group had olfactory dysfunction compared to 7.4% of the controls (P=0.001). Multiple regression analysis indicated that being men and low-density lipoprotein cholesterol (LDL-C) were related to olfactory dysfunction in the total population (OR: 4.55, P=0.037, and OR: 0.94, P=0.037). Still, it was only associated with LDL-C in the CKD group (OR: 0.93, P=0.013).

Conclusion: Based on the findings of this study, CKD and DM patients had a higher prevalence of olfactory dysfunction than the controls, which could be associated with some preventive nutritional factors. This information may help perform a screening program and early intervention on olfactory dysfunction in these systematic diseases.