CASR and primary hyperparathyroidism: While primary hyperparathyroidism is mostly treated surgically, secondary hyperparathyroidism can be treated pharmacologically, in particular by stimulating the CaSR either through the FDA-approved cinacalcet, a synthetic positive allosteric CaSR modulator, or with the newly clinically approved etelcalcetide, a recently developed synthetic CaSR agonist (Nemeth et al., 2004; Fraser, 2009; Cunningham et al., 2011; Hamano et al., 2017).