Current Practices in Monitoring Children and Adults With X-linked Hypophosphatemia: A Global Survey of Expert Experience

Abstract

This report provides recommendations for X-linked hypophosphatemia (XLH) monitoring based on current monitoring practices of experts in the management of XLH in children (<18 years) and adults. We surveyed 43 international experts in XLH to determine their monitoring practices for children and adults with XLH, including pregnant and lactating women. In the initial evaluation of children and adults with XLH, experts consistently obtain a family history of XLH or hypophosphatemia, a history of fractures and dental infections, and assess pain through age-appropriate clinical interviews or caregiver reports. They measure height, weight, and blood pressure and conduct DNA analysis of multiple genes associated with hypophosphatemia including the PHEX gene. For children follow-up, experts arrange follow-up every 3 to 6 months assessing height, weight, and blood pressure and examining for skeletal deformities. Laboratory tests in children include serum phosphorus, corrected total/ionized calcium, alkaline phosphatase, renal function, and PTH and spot morning urine for calcium, creatinine, and phosphorus. During adult follow-up, experts assess patients every 6 to 12 months, with a clinical examination focused on skeletal deformities and joint involvement. The laboratory profile is completed at least once a year. In the presence of bone pain, experts conduct X-rays both in children and adults to evaluate for fractures or joint damage. With respect to nephrocalcinosis, renal ultrasound is suggested on an annual basis or less frequently when monitoring children and adults with XLH. Experts conduct a dental assessment at baseline and then every 6 to 12 months for all patients with XLH. The findings of the survey inform practice for assessing new patients with XLH, monitoring existing patients, and identifying areas for future research. All recommendations based on these practices are weak with very low-quality evidence.