case_images: PMC9751939_01
case_images: (A) The family pedigree of this case. The patient is described as II-4 (arrow), and her son is described as III-1. (B) Genetic mutations in PHEX (c.1645 C > T, p. Arg549X). (C) Radiograph of deformities in the lower extremities. (D) CT findings of paraspinal ligament ossification (arrowheads).
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case_images: PMC9751939_01_fendo-13-1004624-g001.jpg
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case_images: Figure 1A ). Furthermore, an elevated serum full-length FGF23 level (127 pg/mL; measured by ELISA [reference range: 16-69 pg/mL]) in the son was revealed at 10 years old. Arg549X), which led to the definitive diagnosis of XLH ( Figure 1B ). The skeletal investigation showed deformities of the lower extremities ( Figure 1C ). In addition, she suffered from paraspinal ligament ossification ( Figure 1D ).
case_images: Changes in the trough (end of the dosing interval) serum phosphate levels (blue line) and TmP/GFR (orange bar) over 96 weeks of burosumab treatment. The gray zone in the panel indicates values within reference range (2.5-4.5 mg/dL), and the yellow and pink zones indicate the doses of burosumab and evocalcet, respectively.
case_images: fendo-13-1004624-g002.jpg
case_images: PMC9751939_01_fendo-13-1004624-g002.jpg
case_images: f2
case_images: As shown in  Table 1  and  Figure 2 , the patient's trough (at end of dosing interval) serum phosphate levels and TmP/GFR unexpectedly remained low even after starting burosumab treatment. Figure 2 , the serum trough phosphate level started to increase 28 weeks after burosumab treatment, and the TmP/GFR also increased 36 weeks after the treatment ( Figure 2 ). Furthermore, the serum albumin adjusted calcium and intact PTH levels decreased in the same period ( Table 1 ).