Aim: There is no study predicts the development of complications with laboratory parameters in patients with primary hyperparathyroidism (PHPT). We aimed to determine the laboratory parameters that predict the development of osteoporosis or nephrolithiasis in patients with PHPT and identify high-risk patients. Methods: This multicenter retrospective cross-sectional study was conducted between January 2018 and January 2020. The study group consisted of 389 patients who were diagnosed with PHPT (68 patients without surgical indications and 321 patients with PHPT who underwent surgery), and 451 individuals without any additional disease as a control group. Patients’ data was obtained from the hospital automation system. All patients were divided into three groups (control, unoperated and operated), and laboratory parameters were compared. Results: The Wisconsin index (WIN), which is used to detect hyperfunctional glands in addition to parathyroid adenoma in PHPT, and the Parathyroid functional index (PFIndex), which is used to differentiate HPT secondary to vitamin D deficiency, can identify patients at high risk of nephrolithiasis or osteoporosis in patients with PHPT. In patients who have been operated on due to PHPT-related complications, the WIN value of 283.29 showed 95% sensitivity and 72% specificity in predicting osteoporosis, while the PFIndex of 36.43 had 86% sensitivity and 68% specificity for predicting nephrolithiasis. Conclusion: The WIN and PFIndex can be used to refer patients with PHPT for surgery before the onset of osteoporosis or nephrolithiasis. Although no risk factor could be found for nephrolithiasis, WIN was found as an independent risk factor for osteoporosis.