Hyperparathyroidism in Patients With X-Linked Hypophosphatemia.

Area of Science:

• Endocrinology
• Mineral Metabolism
• Skeletal Biology

Background:

• X-linked hypophosphatemia (XLH) is a rare genetic disorder characterized by elevated FGF23, leading to renal phosphate wasting and impaired bone mineralization.
• The prevalence, pathogenesis, and clinical manifestations of hyperparathyroidism in adult XLH patients remain largely undocumented.

Purpose of the Study:

• To determine the prevalence of hyperparathyroidism in adult XLH patients.
• To investigate factors influencing parathyroid hormone (PTH) concentrations in XLH.
• To assess the prevalence of hypercalcemic hyperparathyroidism and its clinical outcomes.

Main Methods:

• An observational study involving 68 adult XLH patients and 136 matched healthy volunteers.
• Standardized clinical assessments and biochemical analyses were performed.
• Primary endpoint: proportion of patients with hyperparathyroidism; Secondary endpoints: factors affecting PTH and prevalence of hypercalcemic hyperparathyroidism.

Main Results:

• XLH patients exhibited significantly higher PTH levels (53.5 ng/L) compared to controls (36.0 ng/L).
• Hyperparathyroidism was diagnosed in 25% (17/68) of XLH patients.
• A positive correlation between PTH and calcium, and a negative correlation between PTH and phosphate were observed in XLH patients. Ten percent (7/68) had hypercalcemic hyperparathyroidism.

Conclusions:

• Hyperparathyroidism is a common complication in adult XLH patients, suggesting disrupted PTH regulation.
• Early-onset hypercalcemic hyperparathyroidism in XLH is effectively treated by parathyroid surgery, normalizing calcium and PTH levels.