Kılıç, EsatGönüllü, EdipAdanaş, CihanAtmaca, MuratÖzbay, Mehmet FatihÖzkan, Sezai2023-03-222023-03-2220212717-94432757-5241https://doi.org/10.4274/forbes.galenos.2021.33043https://search.trdizin.gov.tr/yayin/detay/516415https://hdl.handle.net/20.500.14034/993Objective: We hypothesize that tissue hypoxia would increase erythropoietin, as well as parathormone (PTH), secretion. To verify this hypothesis, patients who had undergone orthopedic surgery with a pneumatic tourniquet were evaluated for endogenous tissue hypoxia. Methods: This study included 20 patients who underwent orthopedic surgery with a pneumatic tourniquet, wherein, 6 had diagnostic arthroscopy and 14 had anterior cruciate ligament reconstruction. All operations were performed under spinal anesthesia. The paired t-test was used to detect the differences between serial concentrations of parathyroid hormone, erythropoietin, calcium, and phosphorus levels before and after ischemia, where “p values” of <0.05 were considered significant. Results: The average duration of ischemia that patients were exposed to during surgery was 57.40±22.65 min. After ischemia, parathyroid hormone and erythropoietin levels were significantly elevated (p<0.001; p<0.001). No significant difference was found in calcium and phosphorus levels in patients before and after ischemia. A positive correlation was found between parathyroid hormone and erythropoietin levels (p<0.05). Conclusion: Our study is the first to show that the increase in erythropoietin levels in response to tissue hypoxia and increases the release of PTHeninfo:eu-repo/semantics/closedAccessArticle10.4274/forbes.galenos.2021.3304323171174516415