Serrano Lorenzo, PabloCoya, Olga N.López Jiménez, AnaBlázquez Encinar, AlbertoDelmiro, AitorLucía Mulas, AlejandroArenas, JoaquínMartín, Miguel A.Santos Lozano, AlejandroMiguel Reyes, Montserrat deEt al.2021-06-032021-06-032021Serrano Lorenzo, P., Coya, O. N., López-Jiménez, A., Blázquez, A., Delmiro, A., Lucía, A., Arenas, J., Martín, M. A., Santos Lozano, A., Cueto Felgueroso, C., Fernández-del Pozo, A., & Miguel-Reyes, M. (2021). Plasma LDH: A specific biomarker for lung affectation in COVID-19? Practical Laboratory Medicine, 25, e00226. https://doi.org/10.1016/j.plabm.2021.e002262352-5517http://hdl.handle.net/11268/10081Objectives We aimed to determine whether the plasma profile of lactate dehydrogenase (LDH) isoenzymes is altered in patients with COVID-19, and whether this is attributable to a specific release of LDH-3, the main LDH isoenzyme expressed in lungs. Design We collected fresh plasma aliquots from 17 patients (LDH range, 281–822 U/L) and seven controls (LDH ​< ​230 U/L). In-gel relative activity of the different LDH isoenzymes was determined by electrophoresis and densitometric analysis. Results Despite the expected higher total LDH activity levels in patients (p ​< ​0.001), the in-gel relative activities of LDH isoenzymes did not differ between patients and controls (all p ​> ​0.05). We found no correlation between total plasma LDH activity and the in-gel relative activities of the different LDH isoenzymes, including LDH-3. Likewise, there was no correlation between LDH-3 and various routine haematological and serum parameters that have been previously reported to be altered in COVID-19 (such as lymphocyte count, albumin, alanine and aspartate aminotransferase, creatinine, C-reactive protein, or ferritin). Conclusions Our findings suggest that elevation of plasma LDH activity in patients with COVID-19 is not associated to a specific release of LDH-3 into the bloodstream, and do not support the use of LDH as a specific biomarker for lung affectation in patients with COVID-19.engAttribution-NonCommercial-NoDerivatives 4.0 Internacionalhttp://creativecommons.org/licenses/by-nc-nd/4.0/Infecciones por coronavirusMembrana celularjournal article10.1016/j.plabm.2021.e00226open accessMedicina clínicaEnfermedad transmisible