Bone Health and Linear Growth in Children With Familial Hypoparathyroidism Treated With Human Parathyroid Hormone 1-34.

Height-for-age Z-scores (HAZ) differed significantly between APS-1 and CaR groups during PTH therapy, with APS-1 remaining below 0 while CaR increased.

• Mean HAZ remained below 0 in the APS-1 group at all ages during PTH therapy
• HAZ increased in the CaR group over time on PTH therapy
• Age by group interaction P < .0001
• Study included 18 APS-1 patients and 9 CaR patients with mean baseline age of 13.7 ± 5.5 years

Lumbar spine BMD Z-scores were within normal range for both diagnostic groups during PTH therapy.

• Mean LS-BMD-Z were normal (BMD-Z: 0 ± 1) for both APS-1 and CaR groups
• Data were derived from pooled lumbar spine dual-energy x-ray absorptiometry measurements
• Longitudinal mixed-effects modeling was used to examine impact of age and PTH duration

Lumbar spine trabecular bone score Z-scores (LS-TBS-Z) differed by diagnostic group, with CaR showing an upward trajectory and APS-1 remaining stable near 0.

• Mean LS-TBS-Z were near or above 0 for both groups overall
• CaR group showed an upward trajectory in LS-TBS-Z according to time on PTH
• APS-1 group maintained a LS-TBS-Z of approximately 0
• Time by group interaction P = .02

Greater APS-1 disease severity (≥7 manifestations) was associated with lower LS-BMD-Z and LS-TBS-Z compared to less severe APS-1 or CaR groups.

• APS-1 patients with ≥7 disease manifestations had lower LS-BMD-Z than those with fewer manifestations or CaR patients
• APS-1 patients with ≥7 disease manifestations also had lower LS-TBS-Z
• The study assessed associations of APS-1 disease severity with both BMD-Z and TBS-Z as a secondary aim
• This finding underscores that disease burden within APS-1 independently affects bone outcomes

This study was a secondary analysis pooling data from prior studies of hypoparathyroidism treated with PTH 1-34 injections.

• Data were pooled from studies of hypoparathyroidism due to APS-1 or activating calcium sensing receptor (CaR) variants
• Total sample included 18 APS-1 and 9 CaR patients
• Mean baseline age was 13.7 ± 5.5 years
• Longitudinal mixed-effects modeling was used to assess associations of age and PTH therapy duration with HAZ, LS-BMD-Z, and LS-TBS-Z