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What is X-Linked Hypophosphatemia (XLH)?

  • X-Linked Hypophosphatemia (XLH) is a heritable bone condition characterized by low blood levels of phosphorus (hypophosphatemia) and rickets in childhood
  • A change in a gene called PHEX causes XLH
  • Bone cells with the change in PHEX produce excessive amounts of FGF23, an important hormone that regulates phosphorus balance
  • Excess FGF23 results in an increase in renal phosphorus excretion, lowering the blood phosphorus level
  • This hypophosphatemia results in impaired accumulation of mineral in the skeleton
  • The resulting undermineralized bones are structurally weak, interfering with normal growth and development leading to characteristic deformities
  • Treatment strategies attempt to enhance the phosphorus level by providing oral supplements or with agents that block FGF23 action at the kidney to reduce losses

The Yale Bone Center

Credit: Robert A. Lisak

The Yale Bone Center (YBC) was founded by Dr. Karl Insogna, an internationally recognized expert in metabolic bone disorders, and is currently directed by Dr. Peter Tebben. The YBC partners with the YC-XLH, providing consultative care for adult patients with osteoporosis, genetic disorders of the skeleton, and other conditions affecting bone and mineral metabolism. The YBC is highly regarded for its comprehensive clinical care and expertise in complex metabolic bone diseases, and is comprised of the following integrated services:

  1. Consultative Clinical Service
    This consultative service, staffed by Yale faculty physicians, provides specialized care at three Connecticut locations: North Haven, New Haven, and Stamford. Patients are referred from throughout the region and beyond for expert evaluation of common and complex disorders of bone and mineral metabolism.
  2. Bone Densitometry Service
    The Bone Densitometry Service performs bone density studies for both clinical care and research. The service is located on the 10th floor of the East Pavilion at Yale New Haven Hospital. All studies are interpreted by a YBC physician.
  3. Mineral Metabolism Laboratory
    The Mineral Metabolism Laboratory offers clinical assessments of circulating vitamin D metabolite levels throughout the Yale Health System, as well as providing analytical support for a wide range of patient-oriented research studies conducted by investigators across the Yale academic community.

The Pediatric Metabolic Bone Clinic

The Pediatric Metabolic Bone Clinic cares for children with disorders of bone and mineral metabolism, including XLH and other disturbances in phosphate metabolism, osteogenesis imperfecta, and skeletal dysplasias. The clinic coordinates the services of endocrinology, radiology, physical therapy and rehabilitation, and orthopaedics, through its multi-disciplinary approach to patient care. The Clinic is located at One Long Wharf Drive in New Haven, CT; patients are referred to the Clinic throughout the northeast region and beyond.

Clinicians Include:

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