Osteomalacia and Vitamin D Deficiency Myopathy

Sit in a firm chair, fold your arms across your chest, and stand up five times without using your hands.

If you cannot do it, and your bones ache too, ask your doctor for a vitamin D blood test. Ask for it by name: 25-hydroxy vitamin D. Ask even if a previous bone blood test came back normal, because that test looks at a different problem.

Takes less than 2 minutes. No equipment needed.

Before you try it. If you have a sharp, well-localised pain in one spot in a bone, especially the groin, hip or pelvis, that hurts when you put weight on it, do not do the test. That needs looking at first, the same week.

The Verdict

A normal bone blood test does not rule out a vitamin D problem in your muscles.

Vitamin D is what lets your body put mineral into bone, like the cement that sets concrete. Run low for long enough and your body keeps building the scaffolding but never sets it hard, so the bones ache under load and crack in odd places. The same shortage separately starves the fast, powerful muscle fibres in your hips and shoulders, which is why the aching and the weakness turn up together, and why fixing the shortage fixes both.

What this actually is: two problems from one shortage, soft bone and weak muscle, and they do not arrive at the same time.
The myth that won't die: that a classic crack on an X-ray is how you spot it. It showed up in only 7 of 26 confirmed cases.
Start here: ask for the vitamin D blood test, and do not let a normal general bone blood test talk you out of it.

Best for

Adults with deep aching bones and weakness getting out of a chair, especially with gut problems, previous bowel or weight-loss surgery, long-term antacids, little sun, or an osteoporosis label that has not behaved like osteoporosis.

Skip if

Your vitamin D is already normal. Four large trials found that supplementing does nothing for strength, movement or pain when you are not short, so this page is not about you.

Want the full evidence? Keep scrolling

What Works

Everything below is graded. The most important thing on this page is a blood test, and the second most important is a sequence: fix the shortage, then load the body. Nobody has run a trial on that sequence, and that is stated where it matters rather than hidden.

Dark cinematic study of bone and muscle tissue

Tier 1 — Strong Evidence

Measure vitamin D, and do not use the general bone panel as the gate HIGH

In 55 vitamin D-deficient women, muscle power was impaired to the same degree whether or not their general bone blood marker was raised. The researchers concluded that marker cannot be used to screen for the muscle problem, and that the vitamin D level itself is the only reliable test (Glerup 2000).

Timeline: immediate. This is a blood test.

Tier 1 — Strong Evidence

Medical correction of a confirmed shortage, run by the prescriber MODERATE

Strong that the shortage needs correcting. Moderate that correcting it restores muscle, because the studies showing recovery had no placebo group. In the one study that measured it, every muscle measure improved significantly by 3 months, and full recovery took 6 months or more, with peak force the last thing to come back (Glerup 2000).

This is a medical treatment, not a physical therapy treatment. Where vitamin D is indicated in someone over 50, current guidance prefers a steady daily dose over occasional very large ones (Demay 2024). The dose is the prescriber's decision.

Tier 1 — Sequencing

Do not load a soft skeleton before treatment has started MECHANISTIC ONLY

Labelled honestly: no trial has tested loading timing in this condition. The reasoning runs from the tissue itself. Bone that has not set hard develops cracks under ordinary load, and those cracks turned up in 7 of 26 confirmed cases (Reginato 1999; Priemel 2010). This is the most consequential recommendation on the page and the least well evidenced, and both halves of that sentence are true.

Exercise Prescription

Read this before the table. No trial has tested exercise in this condition, and no trial has tested when in the treatment course exercise should start. The only published dose in this whole area comes from a study in older adults who did not have this condition, where resistance training three times a week for 13 weeks raised strength by 23%. The numbers below are a cautious, conventional starting point chosen so they can be done without loading a sore bone hard. They are a starting point, not a proven prescription. If you have been told you have a crack or a stress fracture in a bone, do none of this until you are cleared.

Sit-to-stand from a chair — 3 × 5-8, dailyFirm chair, feet flat, arms folded, stand up without pushing off, sit down slowly. Use your hands at first if you need to. Effort in the thighs is fine. Sharp pain in a bone is not.

Supported heel raises — 3 × 8-10, dailyHold a worktop, rise onto your toes slowly, lower over three seconds. Calf effort is fine. Sharp pain in the foot or shin means stop.

Side-lying leg lift — 2 × 10 each side, dailyLie on your side, top leg straight and in line with your body, lift about a foot, lower slowly. Aching at the side of the hip is expected. Sharp pain in the hip bone is not.

Wall push-ups — 2 × 8-10, every other dayArm's length from a wall, hands at shoulder height, bend the elbows to bring your chest toward the wall, push back.

Short flat walks — 10-20 minutes, most daysLevel ground, comfortable pace. Build the time before you build the pace. Stop and rest if one spot in a bone starts to hurt.

Tier 2 and Tier 3 — the rest of the hierarchy

Tier 2 — Screen for an absorption problem MODERATE
Trouble absorbing food from the gut was the single commonest cause in the largest confirmed series, 13 of 26 cases, and this can present with no gut symptoms volunteered at all (Reginato 1999; Kozanoglu 2005).

Tier 2 — Review long-term medications with the prescriber MODERATE
Long-term high-dose antacids have produced this condition outright (Insogna 1980), and epilepsy medicines and steroids raise the risk (Kupisz-Urbańska 2021). Do not stop anything yourself.

Tier 2 — Measure strength as a number, twice MODERATE
Sit-to-stand count and knee extension force, written down. There is no published threshold for what counts as a meaningful change in this condition, so the same person measured twice is the only usable signal.

Tier 3 — Graded resistance training once treatment is under way EMERGING FOR THIS CONDITION
Resistance training itself is strongly supported in older adults. It sits at Tier 3 here only because nobody has tested it in this condition or established when in the treatment course it should begin.

What Doesn't Work

Adding vitamin D for someone who is not short, expecting strength or pain relief. DO-HEALTH randomised 2,157 adults over 70 for three years and found nothing on any of its six main measures. The VITAL trial's physical performance arm (1,054 people) was null. Mølmen raised blood levels by 49% across 28 weeks alongside resistance training and changed nothing. A pooled analysis of individual participants was null even in the mildly low group. If your baseline is already adequate, supplementing is not fixing anything.
Vitamin D for general aches and pains. A pooled analysis of trials in chronic non-specific musculoskeletal pain returned an effect of essentially zero (0.004, with a range from −0.248 to 0.256), and a Cochrane review of 10 studies and 811 people found no consistent benefit. The link in observational data is real; the causal direction is backwards.
Waiting for the classic crack on an X-ray. It appeared in 7 of 26 confirmed cases. Requiring the textbook sign misses roughly three-quarters of them.
Using the standard bone marker as the screen. It is a test for the bone half of the problem, and the muscle half runs ahead of it.
Treating the weakness as being out of shape and prescribing a strengthening programme first. The programme is not wrong. The sequence is.
More is better dosing. In the pooled individual-participant analysis, bigger jumps in blood level tracked with slightly worse peak strength, with measurable downsides in the leaner participants. That is a subgroup finding in 260 people and it is not a harm claim. It is a reason not to treat "more" as the safe default.

Red Flags

Any of these means stop and get seen, not wait and see

New or worsening sharp pain in one spot in a bone during or after loading, especially the groin, hip, pelvis, ribs or shoulder blade. In softened bone this is a crack until proven otherwise. Stop loading.
Weakness that is getting worse despite treatment. Persistent weakness after the vitamin D has been corrected needs a different diagnosis, not more vitamin D.
Unexplained weight loss, night pain, or a history of cancer alongside the bone pain.
Any numbness, pins and needles, bladder or bowel change, or weakness on one side only. That is not this condition.
Severe weakness with rapid onset, or trouble swallowing or breathing. Urgent medical assessment.
Bone pain with no cause found and no vitamin D level ever measured. Not an emergency. It is the referral this page exists to trigger.

Refer to: GP for the vitamin D level plus calcium, phosphate, the bone marker and the parathyroid hormone level, and for coeliac testing or a gut referral where absorption is in question. Endocrinology where the results are abnormal and the cause is unclear. A&E or urgent orthopaedics for a suspected crack, particularly at the hip.

Return to Training

Every item below is a checkpoint, not a tested threshold. No trial has established return-to-activity criteria for this condition, so these are written to be binary and observable rather than felt.

Vitamin D has been measured, the result is known to you, and treatment has started if it was low
The prescriber owns the medication decision, and you can say who that is
Absorption, medication and diet causes have been screened, and anything found has been acted on
Strength was measured with a number at the start (sit-to-stand count and/or knee extension force)
Strength has been re-measured and has measurably improved, or a 3-to-4-month non-response referral has been made
Bone pain has been absent for at least 2 consecutive weeks
You can do 5 sit-to-stands from a standard chair without using your arms
You can climb a full flight of stairs, one foot per step, without pulling on the rail
You understand that a normal general bone blood test did not and does not rule this out
You can name the red flags, particularly new sharp pain in one spot in a bone under load
You understand the timeline is months rather than weeks, and that peak strength is the last thing to return

Impact work and heavy loaded lifting come back last, and only once bone pain has been absent for several weeks. Any new sharp pain in a single spot in a bone sends you back to the offloaded phase and to a medical review, not to a deload.

The Full Picture — Anatomy, Diagnosis & Evidence

What's Actually Going On

Dark cinematic study of bone architecture

Vitamin D drives how much calcium and phosphate you absorb from food. When it stays low, the cells that build bone keep laying down the protein scaffolding, but there is not enough mineral to set it. The skeleton fills with soft, unset seams. A study of 675 bone samples found this soft-seam pattern in more than a quarter of them, and found none of it in anyone whose vitamin D level sat above 75 nmol/L, which is 30 ng/mL (Priemel 2010). Soft bone under normal load develops cracks in characteristic places.

The muscle problem is a separate injury, and this is the part most write-ups get wrong. Muscle samples from confirmed cases show shrunken and dying fibres, disorganised internal structure, and specifically the wasting of the fast, high-force fibres (Yoshikawa 1979). Two mechanisms are proposed: a shortage of phosphate inside the muscle cell starving its energy production, and reduced vitamin D action on how the cell handles calcium. Those fast fibres are what you use to stand up and climb stairs, which is why the weakness shows up there rather than in the hands or feet.

The two problems are not synchronised. In 55 deficient women measured against 22 controls, muscle function was impaired to a similar degree whether or not the standard bone marker was raised (Glerup 2000). The muscle injury can be fully present before the bone injury shows up on any routine blood test.

How to Identify It

Dark cinematic study of the hip and thigh

There are no published accuracy figures for any hands-on test in this condition. Across 192 papers, not one reported how good a physical test is at catching it or at ruling it out. That absence is real and it is stated rather than filled in.

It also creates a specific trap, because this condition does have plenty of percentages, and they mean something different. Numbers like "bone pain in 23 of 26 cases" tell you how often a feature turns up in someone who definitely has the condition. They say nothing about how often it turns up in someone who does not, which is what an accuracy figure would tell you. Put in an accuracy column they would read as test performance, and they would be wrong.

Deep, aching, poorly localised bone pain No accuracy figures published
Weakness in the hips and shoulders, with normal sensation and normal reflexes No accuracy figures published
Difficulty rising from a chair or climbing stairs, out of proportion to general fitness No accuracy figures published
Bone tenderness on firm pressure over ribs, sternum, pelvis or shin No accuracy figures published
A waddling walk, when present. Absent in many No accuracy figures published

The one finding that decides it is not a physical test. It is the vitamin D level, requested with calcium, phosphate, the bone marker and parathyroid hormone. The single most important sentence on this page is that a normal panel of the other four does not rule out the muscle problem.

What should be absent: numbness, pins and needles, or weakness on one side only. Any of those points somewhere else entirely.

The Debate

No clinical practice guideline exists for this as a physical therapy condition as of August 2026. The relevant guidance is hormonal, and two authoritative documents currently look like they contradict each other.

How much vitamin D is enough?

Priemel 2010, 675 bone samples

No soft-seam pattern found in anyone above 75 nmol/L (30 ng/mL). The authors argue supplementation should reach that level to keep the skeleton healthy.

vs

Demay 2024, Endocrine Society guideline

Suggests against routine supplementation above the standard dietary intake in healthy adults under 75, and found no trial evidence supporting routine testing in the general population.

Both, and they are not actually in conflict. Priemel asks at what level bone sets hard, using tissue. Demay asks whether dosing unselected healthy people prevents disease, using trials. A tissue threshold is not a screening policy. Use Demay for the person with no symptoms and no risk factor. Use Priemel's number for reading a result you already have in someone who is symptomatic.

Does vitamin D improve muscle strength?

Beaudart 2014, 30 trials, 5,615 people

A small but statistically significant benefit to strength overall.

vs

DO-HEALTH 2020 (2,157), VITAL 2024 (1,054), Mølmen 2021, Bislev 2022

Null. Four independent programmes, none finding a muscle or performance benefit.

The resolution is inside the positive paper. Beaudart's own breakdown puts the benefit in people who started below 30 nmol/L and in those aged 65 and over; in the younger group the effect ran through zero. The later trials recruited healthy, mostly topped-up volunteers and found exactly the null that breakdown predicts. A small average driven by a deficient minority is not a treatment effect for the topped-up majority. The field quoted the average for a decade.

Honest Limitations

The trials were run in the wrong people for the question a therapist is asking

The finding: four independent programmes found no muscle benefit from vitamin D.

The gap: DO-HEALTH recruited adults over 70 with no major health event in the previous five years, good mobility and good thinking. That is close to ideal for detecting a general benefit and close to the worst possible group for detecting a deficiency-correction benefit, because almost nobody in it was deficient. The genuinely deficient group in the pooled analysis was 34 people.

The adjustment: read these trials as answering "should I add vitamin D to this rehab programme?" (no) and not "does correcting a real shortage restore strength?" (they did not test it).

The recovery evidence has no placebo group

The finding: treated patients improved on every muscle measure by 3 months and had normalised almost everything by 6.

The gap: those arms were unblinded before-and-after designs. A strength test repeated three times in the same people measures getting used to the test as well as getting stronger.

The adjustment: the stronger evidence in that study is the gap between deficient women and healthy controls, not the improvement within the group. Treat the timeline as something to plan around, not as a promise.

The diagnostic figures come from a selected referral group

The finding: clean percentages for every clinical feature.

The gap: they come from 26 patients picked out by having had a bone sample taken at a specialist unit. That group is enriched for exactly the diagnostic confusion this page describes, and there is no denominator of people who were tested and turned out not to have it.

The adjustment: use those numbers to know what the condition looks like. Never to estimate how likely it is in the person in front of you.

The Nuance

Dark cinematic study of the spine and pelvis

The nuance here is a substitution rather than an omission, and it runs in a specific direction: this condition does not usually get missed into nothing, it gets given somebody else's name.

In the 26 confirmed cases, two were diagnosed with polymyalgia rheumatica, two with fibromyalgia, three presented with a rheumatoid-arthritis-like picture, and two were referred as possible cancer that had spread to bone, because the cracks lit up on a bone scan in several places at once. Six of the 23 with thinned bone looked like straightforward osteoporosis with no cracks at all (Reginato 1999). Every one of those labels leads somewhere: steroids, a pain-management pathway, immune-suppressing drugs, or a cancer workup. The tablet that fixes it is not on any of those paths.

There is a second condition that shares the name and must not be confused with it. Osteomalacia can also be caused by a small tumour or by an inherited disorder that wastes phosphate, with a perfectly normal vitamin D level. Those have their own drugs and their own pathway, and nothing on this page applies to them. The blood test that separates them is the phosphate level sitting low while vitamin D sits normal.

Surgery has no role in the nutritional form. It is a medical condition treated medically, and the only surgical question is whether a displaced crack needs fixing.

How Confident Should You Be

Overall: MODERATE, and that single word hides a wide spread, so here is the spread.

Low vitamin D produces a real weakness in the hips and shouldersHIGH

It can be fully present with a normal standard bone marker, so a normal panel does not rule it outHIGH

The classic X-ray crack is absent in most confirmed casesHIGH

Supplementing people who are not short does nothing for strength or painHIGH (NEGATIVE)

It is routinely mislabelled as osteoporosis, polymyalgia rheumatica, fibromyalgia or arthritisMODERATE-HIGH

Correcting a confirmed shortage restores muscle functionMODERATE

Full recovery takes 6 months or moreMODERATE

Any exercise dose, progression rule or loading threshold for this conditionNO EVIDENCE

Any hands-on test with published accuracy figuresNO EVIDENCE

Any threshold for what counts as a meaningful changeNO EVIDENCE

What would change my mind on "correcting it restores muscle"

A double-blind placebo-controlled trial restricted to adults with a vitamin D level below 25 nmol/L and objectively confirmed weakness, at least 300 people, randomised to a daily dose titrated above 75 nmol/L versus placebo for 12 months, with knee extension force as the main measure. The whole treatment case currently rests on before-and-after data in the only group where a benefit is plausible, and every placebo-controlled trial has been run in people who did not have the disease. A null result there would collapse this half of the page.

What would change my mind on "the bone marker cannot screen for it"

A prospective accuracy study of the standard bone panel against the vitamin D level, and where needed a bone sample, in consecutive adults presenting with unexplained weakness in the hips and shoulders. It would produce the accuracy figures this condition entirely lacks, and would either confirm or retire a finding that is now 26 years old and carried on a single group of patients.

Sources

Priemel M, et al. (2010). Bone mineralization defects and vitamin D deficiency: histomorphometric analysis of iliac crest bone biopsies and circulating 25-hydroxyvitamin D in 675 patients. J Bone Miner Res. PMID 19594303.
Reginato AJ, et al. (1999). Musculoskeletal manifestations of osteomalacia: report of 26 cases and literature review. Semin Arthritis Rheum. PMID 10342386.
Glerup H, et al. (2000). Hypovitaminosis D myopathy without biochemical signs of osteomalacic bone involvement. Calcif Tissue Int. PMID 10821877.
Yoshikawa S, et al. (1979). Osteomalacic myopathy. Endocrinol Jpn. PMID 467350.
Bislev LS, et al. (2022). Effect of daily vitamin D3 supplementation on muscle health: an individual participant meta-analysis. J Clin Endocrinol Metab. PMID 35018442.
Beaudart C, et al. (2014). The effects of vitamin D on skeletal muscle strength, muscle mass, and muscle power: a systematic review and meta-analysis of randomized controlled trials. J Clin Endocrinol Metab. PMID 25033068.
Bischoff-Ferrari HA, et al. (2020). DO-HEALTH randomized clinical trial. JAMA. PMID 33170239.
Chou SH, et al. (2024). Effects of supplemental vitamin D3 and omega-3 fatty acids on physical performance measures in VITAL. J Clin Endocrinol Metab. PMID 38488491.
Mølmen KS, et al. (2021). Vitamin D3 supplementation does not enhance the effects of resistance training in older adults. J Cachexia Sarcopenia Muscle. PMID 33788419.
Gaikwad M, et al. (2017). Does vitamin D supplementation alleviate chronic nonspecific musculoskeletal pain? Clin Rheumatol. PMID 26861032.
Straube S, et al. (2015). Vitamin D for the treatment of chronic painful conditions in adults. Cochrane Database Syst Rev. PMID 25946084.
Demay MB, et al. (2024). Vitamin D for the prevention of disease: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. PMID 38828931.
Kozanoglu E, et al. (2005). Proximal myopathy as an unusual presenting feature of celiac disease. Clin Rheumatol. PMID 15349797.
Insogna KL, et al. (1980). Osteomalacia and weakness from excessive antacid ingestion. JAMA. PMID 7431592.
Kupisz-Urbańska M, et al. (2021). Vitamin D Deficiency in Older Patients: Problems of Sarcopenia, Drug Interactions, Management in Deficiency. Nutrients. PMID 33920130. "sarcopenia" = age-related muscle loss

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