Serum iron indices in COVID‐19‐associated mucormycosis: A case–control study

Background Whether dysregulated iron metabolism is associated with COVID‐19‐associated mucormycosis (CAM) remains unknown. Herein, we compare the serum iron indices in COVID‐19 subjects with and without mucormycosis. Methods We conducted a case–control study enrolling COVID‐19 participants with and without mucormycosis. We compared the baseline serum iron indices (iron, ferritin, total iron‐binding capacity [TIBC], unsaturated iron‐binding capacity and percentage transferrin saturation) between CAM cases and COVID‐19 controls. Additionally, we performed a multivariate logistic regression analysis to assess whether any iron indices are associated with CAM. Results We enrolled 28 CAM cases (mean age 53.6 years old; 78.6% men) and 26 controls (mean age 57.2 years old; 73.1% men). Rhino‐orbital (±cerebral) mucormycosis (85.7%) was the most clinical presentation. Diabetes mellitus was more frequent in the cases than controls (75% vs. 42.3%; p = .015). Hypoxaemia during COVID‐19 illness was more common in controls than cases. The mean serum iron values (33 vs. 45 μg/dl, p = .03) and TIBC (166.6 vs. 201.6 μg/dl, p = .003) were significantly lower in CAM cases than controls. On multivariate analysis, we found a lower TIBC (odds ratio [OR] 0.97; 95% confidence interval [CI], 0.95–0.99) and diabetes mellitus (OR 5.23; 95% CI, 1.21–22.68) to be independently associated with CAM after adjusting for serum iron, ferritin and glucocorticoid therapy. The case fatality rate of CAM was 73.9%. The iron indices were not significantly different between CAM survivors and non‐survivors. Conclusions The CAM is associated with lower TIBC levels than COVID‐19 subjects without mucormycosis, suggesting dysregulated iron metabolism in its pathogenesis. Further studies are required to confirm our preliminary observations.