Hyperinflammatory nutritional index as an exploratory combined inflammatory and nutritional marker: associations with cytokines and β2-microglobulin in COVID-19

COVID-19 is characterized by heterogeneous clinical presentations, ranging from mild disease to severe hyperinflammatory states. While individual inflammatory biomarkers are associated with disease severity, the clinical relevance of combined immunonutritional indices remains unclear. This observational cross-sectional study included 60 COVID-19 patients categorized as ICU, ward, and outpatient groups. The hyperinflammatory nutritional index (HNI), calculated as CRP × ferritin / albumin, was evaluated alongside cytokines and β2-microglobulin. Correlation and ROC analyses were performed. ICU patients exhibited significantly higher inflammatory markers, cytokines, β2-microglobulin, and HNI levels. HNI showed a strong correlation with ferritin ( r = 0.945) and moderate correlations with cytokines. ROC analysis demonstrated a high AUC (0.953) for HNI; however, this finding should be interpreted cautiously given the small sample size and potential mathematical coupling. HNI appears to reflect the combined burden of inflammation and nutritional status rather than an independent biomarker. Its clinical utility beyond individual parameters remains uncertain and requires validation in larger studies.