PTH and Hypocalcemia: In our previous studies, we showed that synthetic monomeric peptide, R25CPTH(1–34), as compared to PTH(1–34), exhibits a moderately diminished PTH1R-binding affinity and decreased cAMP signaling potency in vitro, and that with long-term infusion in mice, R25CPTH(1–34) leads to only minimal calcemic and phosphaturic effects, which corroborates the hypocalcemia seen in the original patient, despite the significantly elevated levels of R25CPTH in the plasma (Lee et al., 2015).