PTH and secondary hyperparathyroidism: Parathyroid hormone (PTH) levels start to increase with the progression of chronic kidney disease (CKD) when estimated glomerular filtration rate (eGFR) falls to approximately 45 mL/minute/1.73 m2 [1]. At the initiation of maintenance dialysis therapy, nearly all patients present with secondary hyperparathyroidism (SHPT), characterized by persistently elevated PTH levels (normal range: <65 pg/mL), with more than 80% of patients exhibiting serum PTH levels exceeding 150 pg/mL [2].