Review Highlight: Iron Metabolism and COVID-19

Since the onset of the COVID-19 pandemic, numerous studies have been focused on understanding the influence of various nutrients on either the susceptibility or the course of the disease. In their recent review Iron metabolism in infections: Focus on COVID-19 (Semin Hematol. 2021 Jul; 58(3):182-187), professor Domenico Girelli and his colleagues from University of Verona, Italy, discussed the connections between iron metabolism and COVID-19 and the role of iron in what is known as “nutritional immunity”. Iron is involved in essential cellular processes, such as oxygen transport, production of energy and DNA synthesis, as well as in immunity and the body’s response to vaccinations.

 

Main points discussed in the article are:

 

• COVID-19 infections are characterized with hyperinflammation because of the increase in pro-inflammatory cytokines, which upregulate ferritin, a marker of intracellular iron stores.

 

• Ferritin is increased in an acute phase and it was found to be significantly higher in non-surviving than in surviving COVID-19 patients as well as in patients with severe compared to non-severe COVID -19 disease. Research data support the usefulness of ferritin as a screening test of hyperinflammation to predict worsening and mortality in hospitalized COVID-19 patients.

 

• Low serum iron was a significant predictor of hospitalization of the COVID-19 infected patients and was associated with low lymphocytes count in critically ill COVID-19 patients.

 

• Hepcidin, the main iron regulator, has not yet been extensively studied in COVID-19 patients, but was consistently found to be increased in the severely ill patients. It negatively correlated with PaO₂/FiO₂ ratio (pressure arterial oxygen to fractional inspired oxygen) and it could predict mortality in ICU patients, independently of age, lung function and other inflammatory biomarkers.

 

• Iron deficiency has been linked to poor responses to vaccinations, pointing out the area of interest when it comes to studying the efficacy of COVID-19 vaccines.

 

The authors conclude that further studies are required to understand the role of iron metabolism in severe viral infections, which could lead to the development of new therapies.