It’s International XLH Day today, established to raise awareness about the disorder.
I always find it a bit challenging to find something to share during awareness campaigns, because I need to be sure that I’m passing on reliable information from reliable sources, so I’m not just muddying the waters more than they already are. As we all know, there’s a lot of junk on the internet, and that’s without even considering the intentional misinformation.
In the health care setting, there’s also a lot of information out there that was once reliable, but has become dated as more research is undertaken and new insights revealed. That’s particularly true for hypophosphatemia, where there’s been a massive jump in the scientific understanding of it. I’m pretty sure (just my impression, no inside information) that as recently as ten years ago, even Ultragenyx, just starting on the process of commercializing burosumab, thought of XLH as purely a pediatric disorder, and were a bit shocked to find out that patients would need treatment for an entire lifetime, not just the first twenty or so years of life. When they published the results of their burden of disease study, it was the first time that any major article addressed the need for adult treatment at any length. (Adult symptoms and treatment are mentioned in “The Clinician’s Guide to XLH,” published years earlier, but only in passing and without, as I recall, any data on how universal the progressive symptoms are.)
Just for the record, I try to avoid referring people to the resources produced by pharma, like those at XLHlink. There’s nothing actually wrong with those sites, and the information there is solid if you want to use it for your own understanding, but it’s open to claims of bias, since there’s an inherent conflict of interest in a site run by pharma. It’s too easy for skeptics to say, “Oh, they’re exaggerating, in order to sell their product.” They’re not, in fact, exaggerating (and I might even say they’re under-describing the extent of symptoms and effects on daily life), but you’ll never convince a skeptic of that fact, so it’s better to share resources that have no inherent bias in favor of a specific treatment.
Unfortunately, there aren’t many reliable sources for quick overviews of XLH. The Wikipedia page is a mess, starting with the first line claiming it’s a form of rickets, and then delving into material that’s not particularly layperson-friendly, while also being way behind the times on standard of care. (I keep trying to find time to go in and fix it, but it’s going to be a huge project, and I never have that much time.) The NIH GARD page is also a confusing/misleading/dated mess. The rating of symptoms as seen always/sometimes/never is particularly confusing, and suffers from the fact that there can be multiple terms for what’s basically the same symptom, e.g., the various forms of calcification that virtually all of us experience in some way (enthesopathy, spinal stenosis, ossification of the posterior longitudinal ligament). Each of these items may be reported only occasionally on their own, but if grouped together would probably fall in the “always” category if judged over a lifetime.
The best quick overview I can recommend is at the website of the National Organization for Rare Disorders under the label of Familial Hypophosphatemia (so it includes the autosomal versions and a brief reference to tumor-induced osteomalacia. You’ll note that Dr. Thomas Carpenter, well-known pediatric XLH expert, contributed to the overview. My only reservation about the article is that it was written a few years ago, so it’s a little dated with respect to treatment options, or else it would likely have presented burosumab as the standard of care, rather than as an alternative to the terrible old treatment.
I also still really like “Insights and recommendations to improve outcomes for people living with XLH,” but it’s a bit long and intense for casual reading. Highly encourage patients/caretakers to read it, and share it with your clinician if they’re not a top expert, but it’s probably not useful for someone who just needs the basics.
There’s one brand new resource that I can recommend, although it’s a bit long and a bit technical (talks about “reabsorption” where a layperson would just talk about “absorption” and “upregulate” instead of “raise,”) and there are some minor translation glitches in a few spots, but it does a good job of laying out the whole-body/whole-life nature of XLH and why it’s a mistake to stop treatment when kids become adults. It’s an interview with a professor of endocrinology in Korea, who seems to have significant experience treating XLH adults. It’s really great to see a clinician advocating for patients and explaining why burosumab shouldn’t be limited to kids. She also does a good job of explaining that XLHers are generally not vitamin D-deficient, we just can’t transform it into active vitamin D, and that there are significant risks (and little benefit) to the old phosphate/calcitriol treatment.
So that’s about it for resources I can recommend at present. I’d like to see more resources available from patient advocate groups (and I do believe plans are int he works to produce them). Materials from patient groups would have the benefit of being both layperson-friendly (written in easier-to-grasp style, instead of medical/academic-speak) and accurate/current. It’s a lot of work to produce them though, especially given how many body systems are affected by hypophosphatemia, since it would be ideal to have separate FAQ sheets for each of the relevant affected systems in addition to a general overview, e.g., bones, tendons & ligaments (calcifications), kidneys, teeth, hearing, muscle, and genes.
What about you? Are you celebrating International XLH Day, and do you have any favorite scientific resources for raising awareness that are NOT from pharma? What hypophosphatemia sub-topic would you like to have more resources about?
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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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