Aims Primary hyperparathyroidism (PHPT) is common disorder in which parathyroid hormone (PTH) is excessively secreted from one or more of four parathyroid glands. Primary hyperparathyroidism (PHPT) is an endocrinological disorder associated with increased systemic inflammation, endothelial dysfunction. The systemic inflammation may cause subclinical decrease in cardiac function. Our aim in our study is to compare the markers of systemic inflammation in preoperative, postoperative period with PHPT, to show that PDW (platelet distribution width) value may be a predictive value for the development of cardiovascular (CVO), thromboembolic events (TBO) in patients with primary hyperparathyroidism. Results In this study, patients who underwent parathyroidectomy for primary hyperparathyroidism between 2014 - 2021 were retrospectively screened. A total of 56 patients who underwent parathyroidectomy for PHPT were included in the study. In addition to demographic and clinical information; PTH, corrected calcium, phosphate, white blood cell (WBC) count, platelet counts and PDW of the patients were recorded before and three months after parathyroidectomy. Systemic inflammatory index (SII) was calculated according to appropriate formula. Discussion The preoperative PDW value of the patients was found to be significantly higher when compared with the postoperative period and control groups. Preoperative platelet value, on the other hand, was statistically significantly higher when compared with control group. PDW values were found to be statistically significantly decreased in the postoperative period compared to the preoperative period in patients. Conclusion Increased PDW value before parathyroidectomy may be a predictive value of inflammatıon and the development of CVO ,TBO. Keywords: primary hyperparathyroidism, PDW (platelet distribution width), platelets, parathyroidectomy It is known to cause subclinical inflammation and subclinical cardiac dysfunction in primary hyperparathyroidism. There are conflicting studies on inflammation markers. Our article is the first to study PDW in primary hyperparathyroidism. High preoperative PDW indicates that PHPT may be a risk factor for cardiovascular events.