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

Abstract

Our study explores the impact of human parathyroid hormone (PTH) 1-34 injections (PTH therapy) on growth, areal bone mineral density (BMD), and bone quality (measured by trabecular bone score, TBS) in hypoparathyroidism due to autoimmune polyendocrine syndrome type 1 (APS-1) or an activating variant of the calcium sensing receptor (CaR). To assess associations of (1) age and PTH therapy duration with age-standardized Z-scores for height (HAZ), BMD (BMD-Z), and TBS (TBS-Z) in CaR or APS-1, and (2) APS-1 disease severity with BMD-Z and TBS-Z. This secondary analysis pooled linear growth and lumbar spine (LS) dual-energy x-ray absorptiometry data from studies of hypoparathyroidism with mean baseline age of 13.7 ± 5.5 years. Comparing the 2 diagnostic etiologies (18 APS-1 and 9 CaR), we examined the impact of age and PTH duration on HAZ, LS-BMD-Z, and LS-TBS-Z using longitudinal mixed-effects modeling. During PTH therapy, mean HAZ remained below 0 in the APS-1 group at all ages, whereas HAZ increased in the CaR group (age by group interaction P < .0001). Mean LS-BMD-Z were normal (BMD-Z: 0 ± 1) for both groups. Mean LS-TBS-Z were near or above 0 and differed by group; CaR showed an upward trajectory according to time on PTH whereas the APS-1 group maintained a LS-TBS-Z of approximately 0 (time by group interaction P = .02). The APS-1 group with greater disease severity (≥7 manifestations) had lower LS-BMD-Z and LS-TBS-Z than the less severe APS-1 or CaR groups. Our study highlights distinct growth and BMD patterns in APS-1 and CaR and underscores the need for careful monitoring and tailored treatment strategies to optimize growth and bone health.