Objective: To investigate the effects of surgical treatment on blood parameters in patients with parathyroid adenoma. Methods: Patients with a diagnosis of parathyroid adenoma, who underwent surgery between November 2011 and April 2016, were investigated retrospectively. These patients were evaluated according to white blood cell, lymphocyte, neutrophil, and platelet counts, hematocrit, mean platelet volume (MPV), neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR), and calcium and parathormone (PTH) levels before and after the surgery. Results: The study included 103 patients. The number of male patients was 22 (21.4%), and the number of female patients was 81 (78.6%). The age of the patients ranged between 7 and 87, and the mean age was 54.7 ± 14.3. Preoperative and postoperative changes in lymphocyte, platelet, hematocrit, MPV, calcium and PTH levels were found to be statistically significant in our study, but the changes in NLR and PLR were not. Conclusion: Hyperparathyroidism is a reason for chronic inflammation and may affect blood inflammation parameters. However, the correlation between NLR, PLR, and serum PTH levels was not statistically significant. This can be explained by the fact that surgery causes a significant change in the number of both platelets and lymphocytes. We found a positive correlation between lymphocyte, neutrophil, and platelet counts, hematocrit, MPV, and serum PTH levels.