Someone asked me recently to recommend a basic XLH resource to give to a new-to-them primary care provider (PCP), so the clinician would have some background information about the disorder. It should have been an easy question, because there have been so many journal articles about XLH in the last couple of years, including several on treatment guidelines. And yet, it took me several days to come up with an answer that I felt confident about.
There are two separate challenges in finding a resource for primary care providers who treat XLHers. The first is that the article needs to be reasonably short and not too heavy on the metabolic details that only a specialist could understand and love. The second is that, despite the universal recommendation that XLHers see an entire team of doctors, there are practical issues with finding someone who can supervise that team effectively, and even with deciding who needs to be a member of that team, which is variable and can change with the patient’s individual needs.
Brief, comprehensive journal article. It’s hard to find anything that meets these criteria. Most articles, especially those talking about the standard of care, are written for specialists, the endocrinologists and nephrologists who need all the nitty-gritty details and charts and numbers that a PCP lacks the context for. And you can’t really expect a PCP to read a dense and necessarily lengthy (to be comprehensive) article, given the demands on their time.
My best suggestion (and I promise it’s not because I’m one of the authors, but because it’s written for a more general audience than the clinicians who are already bone-metabolism experts) is “Whole Body, Whole Life, Whole Family: Patients’ Perspectives on X-Linked Hypophosphatemia,” which you can find here: https://academic.oup.com/jes/article/6/8/bvac086/6607648 It’s a little less than four pages, but it covers the basics of XLH, and, as the title says, it comes from the patients’ perspective, so it doesn’t pass along some of the myths still seen in more “scientific” articles. It also includes a short but solid set of citations to other, more detailed resources, although it’s already a little out of date, since there have been several newer articles about treatment guidelines published in the intervening three years.
The treatment team: who oversees it and who’s on it? The patients’ perspective article includes a section on the need for a team of doctors (multi-disciplinary approach), but it doesn’t address the really critical issue of WHO should be coordinating that team. In theory, at least in the U.S., it should be the primary care provider, but they don’t really have the time or the expertise to do it. The clinician who does have the expertise (maybe) is the specialist, but as a “specialist,” they’re used to, in essence, being a consultant who only addresses the symptoms of their specialty (metabolic issues). They expect the PCP to do the referrals to other specialists. Which, in the end, generally means the patient needs to do the coordinating of the team.
Adding to the difficulty is the fact that not all patients need all possible members of the team at all points in their life. Appropriate team members will almost always include an endocrinologist or nephrologist (whichever is standard in your country), plus a dentist and a primary care provider (to oversee non-XLH issues). At various times in the patient’s life, other possible team members might include a genetics counselor, pain specialist, rheumatologist (for arthritis), orthopedic surgeon, endodontist (or oral surgeon), talk therapist, physical therapist, and/or occupational therapist. To a large extent, it may be up to the patient to decide which of those team members are appropriate at any given time, but there may be times when the PCP should be the one initiating the conversation.
Most PCPs aren’t really equipped to raise those issues, but if they or the patient feels the need for additional services beyond the basic team, it may be useful to give the PCP some guidance on what referrals might be appropriate. Toward that end, the PCP might find one of the more detailed guidelines articles useful, but you might need to prepare them for the daunting size and detail of the articles. They can likely skip over most of the metabolic-treatment sections and focus on the section about the multi-disciplinary aspects of treatment.
In the U.S., Europe, and Canada, I’d recommend this one for any PCP interested in an in-depth article: “XLH Matters 2024: expert insights and practical tools for enhancing care of people living with X‑linked hypophosphataemia” https://pmc.ncbi.nlm.nih.gov/articles/PMC12445020/pdf/13023_2025_Article_3930.pdf At fourteen dense pages, you can see why it might be a bit much to expect a PCP to read for just one patient, but it contains a more comprehensive section than I’ve seen anywhere else on what, exactly, each specialist can do for XLH patients, and some of the challenges these experts have observed when referring to specialists (pages 5-10).
There’s also “X-Linked Hypophosphatemia Management in Adults: An International Working Group Clinical Practice Guideline” https://pmc.ncbi.nlm.nih.gov/articles/PMC12261105/ This is typical of articles written with the endocrinologist/nephrologist in mind, and it barely touches the multi-disciplinary issues. It’s also even longer, a dense seventeen pages long, which is necessary for the specialist, but overkill for the PCP. Plus, I think the GRADE methodology is a stretch, trying to make opinion look like data; the opinions are from top experts, which should be enough without some faux scientific methodology. Still, it’s a solid article with deep insights in XLH treatment for any clinician who has the time and interest to study it.
Looking for a future resource. Considering how hard it was for me to come up with an easy answer to this question, which I’m sure many patients wonder about, I think there’s a real need for a resource that has the necessary scientific basics, without going too deep into metabolic details, plus more guidance on when and why referrals may be needed to specialists other than an endocrinologist, as well as who should be responsible for overseeing the team. I suspect that in most cases, patients will end up being the team manager, which means that we need more guidance on when we should seek referrals to the other specialists and what qualifications we should look for in those specialists.
I would really love to see some organization tackle this issue with a simplified set of recommendations for PCPs who may be overseeing a multi-disciplinary team for patients, and also a parallel set of recommendations for patients who end up having to do the oversight on their own. This resource would be less about the metabolic-diagnosis/treatment issues, and more about the big picture. It would address three big issues relating to a multi-disciplinary team: 1. which team members may be appropriate (and why), 2. when referrals to those team members are appropriate, and 3. how to locate team members who have the right expertise to treat someone with a rare bone disorder (comparable to finding an endocrinologist/nephrologist who understands XLH, not just bone metabolism in general).
Personally, my biggest challenge has been that last one, finding someone who has the right expertise to treat the non-metabolic aspects of my XLH. I manage my own team, and I have a highly qualified endocrinologist, but I’ve had really terrible experiences with physical therapists who refused to listen to me about the unique aspects of XLH bones/calcifications (plus some good experiences, but more bad than good), and similarly terrible experiences with rheumatologists and one endodontist. I’ve also heard of (but not experienced) horrific experiences with genetic counselors who didn’t know that XLH was genetic, or assumed it was recessive, since most X-linked conditions are. And don’t get me started on orthopedic surgeons who aren’t interested in making sure the bone metabolism issues are under control before surgery. Making sure the team member is someone who can be humble and open-minded when treating a rare disease patient of any sort is a daunting challenge, and not one I have much advice for overcoming. I’d love to hear any suggestions you may have for compiling a really solid team that’s tailored to your individual needs.
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Please note that the author is a well-read patient, not a doctor, and is not offering medical or legal advice.
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