Most conditions announce themselves. You notice something, you worry about it for a week or two, and eventually you ring the surgery. Paget’s disease of bone does not usually work like that. It is far more likely to be found while somebody is looking for something else entirely: a routine blood test where one enzyme sits stubbornly above the reference range, or an X-ray taken for a sore hip that happens to include a section of pelvis that does not look quite right.
That makes the conversation afterwards an awkward one, because the obvious question after an unexpected finding is “what do we do about it?” The honest answer, according to the people who wrote the international guideline, is often less than patients expect.
TL;DR
- Paget’s disease of bone disrupts the normal cycle of bone renewal in one or a few specific bones. It is usually found by accident, through a raised alkaline phosphatase on a routine blood test or an incidental finding on an X-ray taken for another reason.
- The only time anyone has measured how common it is in Ireland was 1983. Researchers reviewed 938 X-rays in Dublin and 714 in Galway and found rates of 1.7% and 0.7% in people aged 55 and over. Dublin’s rate was lower than every one of the 31 British towns surveyed, where the range ran from 2.3% to 8.3%.
- The condition has been fading worldwide for decades. In Lancaster in north-west England prevalence fell from 8% to 0.8% in forty years, and UK diagnoses dropped by more than 60% between 1999 and 2015.
- One 2024 hypothesis links that decline to the domestic open coal fire, noting that lower-prevalence Ireland burned turf rather than bituminous coal. It is a hypothesis, not a settled finding, and it is not a reason to burn anything.
- Treatment works well when it is needed. But the 2019 international guideline recommends treating symptoms rather than chasing the blood result back into the normal range, because a large trial found no fracture benefit from doing the latter.
What the condition actually is
Healthy bone is not inert. It is constantly being dismantled by one set of cells and rebuilt by another, in a slow and tightly regulated cycle that replaces your skeleton gradually throughout life. In Paget’s disease, that cycle goes wrong in specific, localised patches. The dismantling speeds up dramatically, the rebuilding races to keep pace, and the bone that results is laid down in a disorganised way. It is often bigger than the bone it replaced, and more richly supplied with blood vessels, but it is structurally poorer.
The important word is localised. This is not a whole-skeleton condition in the way osteoporosis is. Paget’s disease picks sites, most commonly the pelvis, spine, skull, thigh bone and shin bone, and leaves the rest of the skeleton alone. Many people have only one affected bone and never know.
One point of confusion is worth settling early, because it makes searching online unexpectedly distressing. Paget’s disease of bone is an entirely separate condition from Paget’s disease of the breast and from extramammary Paget’s disease, both of which are skin manifestations of cancer. They share a name only because the same nineteenth-century surgeon, Sir James Paget, described them. If you have been told you have Paget’s disease of bone, what you read about the breast condition does not apply to you.
How it gets found
The usual route is biochemical. Total alkaline phosphatase, often shortened to ALP, is an enzyme that turns up in routine blood panels, and it rises when bone is being remodelled rapidly. The international guideline recommends it as the first-line screening test, with one important caveat: it should always be interpreted alongside liver function tests, because the liver is the other major source of alkaline phosphatase in the blood. A raised ALP on its own does not tell you which organ it came from.
This is worth knowing if you are the person holding the result. “Your alkaline phosphatase is a bit up” is the beginning of a question, not the end of one, in much the same way that an unexpectedly high calcium result needs a follow-up rather than a shrug. A reasonable thing to ask is whether the pattern across the blood tests points towards bone or liver.
If bone looks likely, the guideline recommends plain X-rays of the abdomen, skull, facial bones and shin bones as the initial diagnostic step. Pagetic bone has a characteristic appearance that an experienced radiologist recognises readily. A radionuclide bone scan is then recommended, not to make the diagnosis but to map how many bones are involved, since scans pick up sites that targeted X-rays would miss. MRI and CT are specifically not recommended for diagnosis, though they are valuable for investigating particular complications.
The only time anyone counted it in Ireland
Here is the part that surprised me most. If you want to know how common Paget’s disease of bone is in Ireland, there is exactly one study to read, and it was published in the British Medical Journal in November 1983.
Its opening line is blunt: “Little is known about the occurrence of Paget’s disease of bone in Ireland.” Large radiological surveys had already been done across 31 British towns and 13 towns in nine other European countries, and Ireland had simply not been included. So Detheridge, Barker and Guyer set out to fix that, using exactly the same method as the European surveys so the results would be directly comparable.
They took consecutive abdominal X-rays of people aged 55 and over from film libraries at two hospitals, the Mater Misericordiae in Dublin and Merlin Park in Galway. The films had to show the whole pelvis, the sacrum, the femoral heads and all the lumbar vertebrae, sites involved in 95% of people with the condition. The numbers of men’s and women’s films were similar, and standardised diagnostic criteria were applied.
In Dublin, 938 X-rays yielded 15 cases, an age-standardised prevalence of 1.7%. In Galway, 714 X-rays yielded 4 cases, a rate of 0.7%.
Set against the rest of Europe, those are strikingly low figures. Dublin’s 1.7% was below every single one of the 31 British towns surveyed, where rates ran from 2.3% all the way up to 8.3%. It was also below the three French towns, which ranged from 2.0% to 2.7%. Galway’s 0.7% sat alongside the lowest European rates outside Britain and France.
The authors did not hide how odd they found this. “The low prevalence in Dublin, situated so close to Britain, is remarkable,” they wrote, before noting that it was hard to square with the then-fashionable theory that the disease was caused by a virus, since any such virus would have to be widespread across the water. Their closing sentence is a model of scientific honesty: “There is no evident explanation for the rarity of the disease in western Eire.”
Two caveats matter, and the authors flagged them themselves. Fifteen cases and four cases are small numbers, too small to break down reliably by age. And the study is now 43 years old. No further Irish prevalence survey appears in the published literature since. Whatever the rate is in Ireland today, nobody has measured it in more than four decades.
A condition that is quietly disappearing
What makes that 43-year gap more than a curiosity is that Paget’s disease has been in retreat everywhere since. This is not a subtle trend. In Lancaster, a town in north-west England that once had one of the highest concentrations anywhere, prevalence fell from 8% to 0.8% across forty years. A large analysis of UK general practice records found clinically diagnosed cases dropped by more than 60% between 1999 and 2015. Repeat surveys in other European countries have generally found the proportion affected halving.
That pattern is hard to explain genetically. There is a well-established hereditary component, with mutations in a gene called SQSTM1 being the most common culprit, but genes do not change across two or three generations. And the clearest evidence against a purely genetic story comes from following the families who carry those mutations.
In a study published in early 2025, researchers went back to a group of SQSTM1 carriers who had been scanned, found clear, and scanned again five years later. After a further eight years, 21 of the original 24 had another bone scan. Two had developed the condition, an incidence of roughly 11.9 cases per 1,000 patient-years. The researchers had expected the rate to climb as the group aged. Instead it fell. And when they compared these relatives with their own affected parents, the disease was arriving later and was markedly less severe, a difference significant at p less than 0.001.
In other words: the same genes, the same families, a much gentler disease. Something in the environment that used to trigger it appears to be going away.
The fire in the room
So what was it? Nobody knows. But in 2024 a paper in Calcified Tissue International put forward a hypothesis that is hard to read without thinking about Irish houses.
The argument runs like this. Paget’s disease emerged as a recognised clinical entity in Britain in the late nineteenth century, precisely when British industrialisation was being driven by coal. In the home, bituminous coal was burnt on an open hearth. Working from coal production figures, population data and estimates of what share went to domestic use, the author calculated that exposure to domestic coal burning roughly tripled in Britain across the nineteenth century and began falling after 1900 as homes switched to gas and electricity. The share of coal production going to domestic use fell from around 50% in the seventeenth century to 22% by 1900, 13% by 1975 and 3% by 2000. That curve, rising then falling, tracks the rise and fall of the disease.
The exceptions are what make it interesting. Germany burned plenty of coal but had markedly lower rates, and German homes used closed cast-iron stoves rather than open hearths. Settler populations in North America, Australia and New Zealand who brought British domestic habits with them developed the disease, while the indigenous populations of those countries largely did not.
And then there is one sentence about us. In the low-prevalence regions of Scandinavia and Ireland, the paper notes, wood and peat respectively remained widely used domestic fuels.
Turf, in other words. The fuel that heated a great many Irish homes well into living memory is not bituminous coal, and the hypothesis offers an explanation for something the 1983 authors could not explain at all: why a city 100 miles from Britain had a lower rate than any British town surveyed.
Three honest caveats, because this is the kind of story that gets flattened in the retelling. First, it is explicitly a hypothesis, published as such by a single author, and the paper is candid that nobody has identified what in coal smoke might be responsible. Second, the 1983 Irish data and the 2024 coal paper were not designed together; connecting them is an inference, and a tidy-looking inference is not the same as a demonstrated one. Third, and most importantly, none of this is an argument for burning turf. Solid fuel smoke is firmly established as harmful to the lungs and the heart, which is why Ireland restricts the sale and burning of smoky fuels, and nothing in a bone-disease hypothesis changes that arithmetic.
What it does when it is active
Most people with Paget’s disease have no symptoms at all and never develop any. When it does cause trouble, the commonest complaint is a deep, persistent bone pain in the affected area, often described as a dull ache that does not respond well to position or rest.
Among people who did come to attention historically, a systematic review found bone deformity present in 21.5% at first presentation, hearing loss in 8.9% and a fracture through affected bone in 8.5%. Because pagetic bone can enlarge, trouble also arises from pressure on neighbouring structures: narrowing of the spinal canal where the spine is involved, and hearing loss where the skull is. That hearing loss is often conductive rather than nerve-related, arising from changes in the temporal bone around the ear rather than compression of the nerve itself, which matters because the type of hearing loss shapes what helps. Osteoarthritis in a nearby joint is common, and people with the condition are more likely to need a hip replacement.
Two rare complications, a bone cancer called osteosarcoma and a giant cell tumour, are the ones people find when they search online. They are genuinely rare, and worth keeping in proportion: adult osteosarcoma rates have fallen alongside the decline in Paget’s disease itself. A new, different, escalating pain in an affected bone is the thing to report promptly, in the same way that a sudden change in back pain deserves a proper look rather than a wait-and-see.
Treatment, and the number problem
When treatment is needed, it is genuinely good. Zoledronic acid, a bisphosphonate given as a single intravenous infusion of 5mg over at least fifteen minutes, is authorised across the EU and therefore in Ireland for Paget’s disease of the bone in adults. In two trials involving 357 adults, around 96% of people responded within six months compared with around 74% on daily oral risedronate. In a long-term extension, 88% of those given the single infusion still had a normal alkaline phosphatase five years later, against 47% of the oral group. For most people one infusion is the whole course, with further infusions considered only if the disease returns.
The commonest side effect is a flu-like reaction in the first three days: fever, aches, headache. It affects more than one person in ten, is usually mild to moderate, and paracetamol or ibuprofen taken shortly afterwards reduces it. The regulator specifies that for Paget’s disease the infusion should only be given by a doctor experienced in treating the condition, and it is not used where kidney function is severely impaired.
Now the part that catches people out. Having been told their alkaline phosphatase is high, most patients reasonably assume the aim is to get it back to normal and keep it there. The guideline says otherwise.
This was tested directly. The PRISM trial randomised 1,324 people with Paget’s disease, average age about 74, to one of two strategies: intensive treatment aimed at pushing alkaline phosphatase into the normal range regardless of symptoms, or treatment aimed simply at controlling pain. It ran for an average of three years with fractures as the primary endpoint.
The result was close to a dead heat. Clinical fractures occurred in 46 of 661 people (7.0%) in the intensive group and 49 of 663 (7.3%) in the symptom-led group, and an extension following participants for an average of 7.3 years found no advantage either. On the strength of that, the guideline recommends treatment aimed at improving symptoms over a strategy aimed at normalising the blood result.
It goes further, and the list is striking. There is insufficient evidence that bisphosphonates in Paget’s disease prevent fractures, prevent or treat bone deformity, slow progression of hearing loss, slow progression of osteoarthritis, improve quality of life to a meaningful degree, or prevent cancerous transformation. What they clearly do is relieve bone pain, and zoledronic acid is the one most likely to do it well.
Underlying all of this is a simple mismatch: the number and the symptoms are only loosely related. In PRISM, 635 participants had a raised alkaline phosphatase at the outset, and 295 of them, 46.4%, had no bone pain at all. A smaller study found much the same, with 23 of 55 people with a raised result reporting no pain. Researchers following people after treatment found that pain came back in 9.2% of the zoledronic acid group while the blood result crept up in only 0.7%, and concluded that biochemical relapse and clinical relapse are distinct events.
None of which means treatment should be refused, or that a raised result should be ignored. It means the decision is a conversation about how you actually feel, not an arithmetic problem to be solved. If you have been offered treatment, a fair question is whether it is aimed at a symptom you have or at a number on a page, and what the expected benefit is either way.
Practical steps if this is you
If a raised alkaline phosphatase has turned up on your bloods, ask whether liver function tests were done alongside it, and whether the picture points to bone or liver. If Paget’s disease is suspected, ask whether plain X-rays and a bone scan are planned, since the scan is what establishes how much of the skeleton is involved.
If your skull is involved, ask about a hearing assessment. Hearing change is one of the complications that affects daily life most, and it is easier to address when it is picked up early.
For information and support, the Paget’s Association runs a nurse-led helpline on 0161 799 4646 and can be reached at helpline@paget.org.uk. The charity was founded in 1973 and is UK-based. There is no equivalent Irish organisation devoted to the condition, which is part of why reliable information can be hard to come by here.
At Críonna Health we keep returning to a particular kind of condition: the ones that turn up by accident, affect a small number of people, and sit outside the reach of the campaigns and the screening programmes. Paget’s disease of bone is a good example, and an oddly hopeful one. It is getting rarer and gentler for reasons nobody has pinned down, which is a rare direction of travel in health reporting. The only frustration is that the last time anyone checked how Ireland was doing, the films came out of hospital archives in Dublin and Galway, and the year was 1983.
This article is for general information and is not a substitute for individual medical advice. If you have been told you have a raised alkaline phosphatase or Paget’s disease of bone, discuss your own situation with your GP or specialist.
📷 Photo by Stéphane Juban on Unsplash
