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Anosmia and dysgeusia have a relatively high impact on malnutrition in patients with chronic kidney disease (CDK), according to a systematic review published in Nefrologia.

“Patients with CKD face a myriad of health complications, including but not limited to anemia, electrolyte imbalances, bone metabolism disorders, and severe malnutrition,” the researchers wrote. “Notably, a significant portion also suffers from alterations in taste and smell, which further complicates their condition.”

The systematic review explored interconnections among anosmia (olfactory dysfunction), dysgeusia (gustatory dysfunction), and malnutrition in patients with CKD. Investigators reviewed a total of seven studies: two focused on anosmia and five focused on dysgeusia. All seven studies were of high quality and included a total of 219 patients, of whom 67 had anosmia and 152 had dysgeusia.

Impact of Anosmia & Dysgeusia

Anosmia was linked with worse nutritional status in patients with end-stage renal disease, suggesting olfactory dysfunction as a mechanism of malnutrition, according to the study results. In one study, daily intranasal theophylline showed promise for enhancing olfaction in patients, with 71% showing improved olfactory function after undergoing the intervention for 6 weeks. Researchers called for further investigation into the possible treatment.

“One notable aspect explored across several dysgeusia studies was the potential role of poor nutrient intake, particularly zinc deficiency, as a critical determinant of malnutrition in individuals undergoing dialysis,” they noted.

Zinc supplementation to improve taste dysfunction showed mixed results in the studies reviewed. The contrasting findings point to the complexity of taste perception mechanisms and the need for more research, the authors wrote. In a cross-sectional study, taste alterations correlated with upper gastrointestinal symptoms and malnutrition in patients with CKD.

Directions For Future Research

“Overall, the findings from these studies underscore the multifaceted nature of anosmia, dysgeusia, and malnutrition in [patients with CKD],” the researchers wrote. “These sensory dysfunctions serve as important indicators for assessing nutritional status, especially in [patients with CKD] susceptible to protein-energy wasting.”

Further research should examine the underlying mechanisms behind olfactory and taste perception alterations in CKD, they continued and assessed targeted interventions to enhance nutritional outcomes and overall quality of life in this vulnerable patient population.