GDF15 and COVID-19: Most of the previously performed studies support evidence of higher GDF-15 levels in COVID-19 patients requiring hospitalization and those with a more severe form of the disease [15,16,17,18,19,20,21,22], while others have provided data supporting lower levels of GDF-15 in hospitalized COVID-19 patients or no significant difference between hospitalized and discharged patients, nor between SARS-CoV-2-positive and -negative patients [18,23,24].