Investigating the clinical characteristics of the patients experiencing symptomatic hypercalcemia (HS-PHPT) compared with A-PHPT patients, HS-PHPT patients emerged as older and presented with a more severe hyperparathyroidism, in terms of higher serum calcium, PTH, and total ALP levels, suggesting that hypercalcemia-related symptoms are positively correlated with the parathyroid tumor activity. Here, PTH is linked to Hypercalcemia.