Inflammatory Markers as Predictors of Onset and Recovery of Olfactory and Gustatory Dysfunction in COVID-19 Patients

Background Olfactory and gustatory dysfunctions are widely recognized as characteristic manifestations of COVID-19. However, the relationship between disease severity, inflammatory markers, and the recovery of chemosensory functions remains unclear, particularly in hospitalized patients. This study aimed to evaluate predictive hematological and radiological factors associated with the development and recovery of olfactory and gustatory dysfunction in COVID-19 patients. Methodology This prospective, observational study included 96 hospitalized patients diagnosed with COVID-19 via polymerase chain reaction testing between September 2020 and January 2021. A total of 53 patients with new-onset olfactory and/or gustatory dysfunction and 43 control subjects were selected through online randomization. Visual Analog Scale (VAS) scores were used to assess symptom severity and recovery. Hematological and inflammatory parameters, including neutrophil-to-lymphocyte ratio (NLR), corrected NLR, neutrophil-to-monocyte ratio (NMR), platelet-to-lymphocyte ratio (PLR), C-reactive protein (CRP), and procalcitonin levels, were analyzed. Thorax CT scores were used to determine disease severity. Follow-up evaluations were conducted by telephone at 90 days post-discharge to reassess VAS scores and recovery status. Results Olfactory loss was present in 42 (43.7%) patients, and taste loss in 44 (45.8%) patients. Olfactory dysfunction was significantly associated with age and higher thorax CT scores (p < 0.05). Procalcitonin and CRP levels were significantly associated with the development of both olfactory and gustatory dysfunction (p < 0.05). Lower NLR, d-NLR, NMR, and PLR values were strong predictors of recovery. At 90-day follow-up, 66.7% of patients with anosmia achieved complete recovery, 30.9% showed partial improvement, and 2.4% reported no recovery. All patients with taste impairment recovered (75% complete, 25% partial). Chemosensory dysfunction was more common in patients with milder disease severity. Conclusions Olfactory and gustatory dysfunctions are more prevalent in patients with milder COVID-19 and lower inflammatory burden. Elevated inflammatory markers and severe thoracic involvement were inversely associated with the development and recovery of chemosensory dysfunction. These findings suggest that systemic inflammation may play a detrimental role in neural recovery of chemosensory pathways and highlight the prognostic value of hematological markers in COVID-19 symptom monitoring.