One patient ceased burosumab in the setting of hypercalcemia and constipation secondary to pre-existing tertiary hyperparathyroidism, with pre- and post-burosumab corrected calcium (2.52 mmol/L; 2.67 mmol/L) and PTH concentrations, respectively (10.1 pmol/L; 13.7 pmol/L, normal-range: 1.6-7.2 pmol/L). This evidence concerns the gene PTH and Hypercalcemia.