PTH and cancer: Clinically, PTH measurement is essential for: (1) Diagnostic differentiation: Distinguishing primary hyperparathyroidism (PHPT, elevated PTH) from malignancy-associated hypercalcemia (22); (2) Disease stratification: Identifying SHPT in CKD where mineral dysregulation drives bone disease (26).; (3) Therapeutic monitoring: Guiding vitamin D/calcimimetic therapy in CKD and optimizing teriparatide dosing in osteoporosis (27–30); (4) Surgical confirmation: Validating successful parathyroidectomy through rapid intraoperative decline.