PTH and secondary hyperparathyroidism: Etelcalcetide (Etel), a second-generation agonists of the calcium-sensing receptor (CaSR), was approved by the U.S. Food and Drug Administration (FDA) in 2017 for the treatment of secondary hyperparathyroidism (SHPT), a condition characterised by elevated levels of parathyroid hormone (PTH) levels due to disruptions in calcium, phosphate, and vitamin D. (D'Marco et al., 2023; Patel & Bridgeman, 2018).