Patients with X-Linked Hypophosphataemia need early and life-long multidisciplinary care

Oliver Gardiner

Chair, International XLH Alliance
Chair, XLH UK

Better understanding of X-Linked Hypophosphatemia (XLH) establishes the importance of multidisciplinary treatment of patients of all ages, not just children.

Until recently, X-linked hypophosphataemia (XLH), a rare and life-long phosphate-wasting disorder, has been poorly understood, with limited treatment options. Fortunately, with improved understanding and a promising new treatment, patients have the potential, regardless of age, to experience much healthier, happier lives.

Background

XLH occurs in approximately one in 20,000 births. It is inherited in an X-linked (located on the X chromosome) dominant pattern although it can also occur from spontaneous mutations. Because of the genetic transmission, diagnosing the child of a parent with XLH is relatively simple. Diagnosis of children with spontaneous mutations can be delayed, potentially limiting the effectiveness of treatment, since the sooner the condition is treated, the better the results. . The most obvious symptom of phosphate wasting in children is the bowed legs associated with rickets. In fact, parents of a child with XLH are often stigmatised by the public, because the condition looks like the rickets, which is associated with malnutrition.

Acknowledging that XLH is far more than rickets is just the first step toward better outcomes for patients.

In the past, the vast majority of treatment was focused on straightening and strengthening the paediatric patients’ legs, while ignoring the many other consequences of inadequate phosphate levels, including bone pain and muscle pain/weakness. Clinicians who believe that only the rickets need to be treated fail to address the other issues. This may lead to life-long harm to the patient, and the resulting reduced ability to live a happy life.

A new treatment is available that addresses the root cause of the phosphate-wasting, leading to better mineralisation of paediatric patients’ bones and teeth as well as reductions in other symptoms like pain and muscle weakness. The hope is that these stronger, straighter bones will be far less likely to require invasive surgeries in childhood to straighten the bones or additional corrective orthopaedic surgeries later in life, since in the past, those surgeries often led to a lifetime of chronic pain. 

Improved understanding of XLH

Historically, XLH was considered purely a paediatric disorder, and treatment of adults was controversial, so, many adults went without treatment until they were severely disabled. And even then, there weren’t safe, effective treatment options.

Recently, however, with the help of patients and patient-advocates like the organisation, XLH UK, the nature and severity of adult symptoms have been documented, establishing the need for ongoing treatment for the patients’ entire lives.

It’s now known among the experts (but not yet as widely disseminated as it should be) that adults with XLH no longer have rickets, but experience the same bone pain as children, and in addition, adults experience osteomalacia (soft bones), widespread enthesopathy (calcification of tendons and ligaments), osteoarthritis, pseudofractures, muscle dysfunction, hearing loss, and debilitating fatigue.

A new treatment is available that addresses the root cause of the phosphate-wasting, leading to better mineralisation of paediatric patients’ bones and teeth as well as reductions in other symptoms like pain and muscle weakness.

Since XLH is a whole-life, whole-body disorder, it is important for both paediatric and adult primary care physicians to understand the need for multidisciplinary care. The new treatment for children has recently been approved for adults by the European Medicines Agency, so referral to an endocrinologist, regardless of the patient’s age, is absolutely critical to a good outcome. In addition, patients, at various times in their lives, will need a combination of several health care providers, including primary care, orthopaedists, dentists, physiotherapists, and occupational therapists. Referral to these specialists is critical to healthy lives.

XLH is far more than rickets – future treatment must acknowledge that

Acknowledging that XLH is far more than rickets is just the first step toward better outcomes for patients. There’s still much more work for experts and patient-advocates to do. In particular, international evidence-based treatment guidelines, developed by expert multidisciplinary clinicians in collaboration with patients, are desperately needed to ensure consistency in care and best possible outcomes for all patients at all ages. Easily accessible, reliable information on the disorder should also be provided to patients to avoid assumptions or outdated knowledge.