ConditionBones, joints & muscles
Osteomalacia
Osteomalacia means "soft bones". It happens when newly formed bone does not mineralize properly with calcium and phosphate, most often because of a lack of vitamin D. It causes aching bone pain, especially in the hips, pelvis, lower back and legs, muscle weakness that makes climbing stairs hard, and small fractures. In children the same problem is called rickets. Osteomalacia is usually curable with vitamin D, calcium and treatment of the underlying cause.
Also called: Soft bones, adult rickets, vitamin D deficiency bone disease
At a glance
- What it is
- Poor mineralization of bone, making bones soft and painful.
- Main cause
- Vitamin D deficiency, from little sun exposure, poor diet or malabsorption.
- Other causes
- Kidney or liver disease, phosphate loss, some medicines, rare genetic conditions.
- Symptoms
- Diffuse bone pain and tenderness, proximal muscle weakness, waddling gait, fractures.
- Treatment
- Vitamin D and calcium, phosphate if low, and treating the cause.
When to get help
See a doctor within a day or two
- Muscle cramps, tingling around the mouth or in the fingers, or muscle spasms (possible low calcium)
- A fracture after minimal trauma, or sudden severe hip or groin pain making walking hard
Book a routine appointment
- Aching pain in the hips, pelvis, lower back, ribs or legs that does not go away
- Difficulty getting up from a chair or climbing stairs, or a waddling walk
- Little sun exposure, darker skin, a covered dress style, or a gut condition, with bone aches
- Bariatric surgery, celiac disease or long-term anti-seizure medicines: ask about vitamin D checks
Usually safe to manage at home
- Low-risk adults: get safe sunlight, eat vitamin D-rich foods, or take a standard supplement at the label dose
What happens in osteomalacia
Bone is constantly renewed. New bone is first laid down as a protein framework (osteoid), which is then hardened with calcium and phosphate. Vitamin D is needed to absorb calcium and phosphate from the gut. When vitamin D, calcium or phosphate is lacking, osteoid builds up without hardening. The bones become soft, bend and develop small cracks called pseudofractures (Looser zones).
Osteomalacia vs osteoporosis
| Osteomalacia | Osteoporosis | |
|---|---|---|
| Problem | Bone not mineralized properly (soft) | Too little bone, but normally mineralized (thin) |
| Main cause | Vitamin D deficiency | Aging, menopause, steroids |
| Pain | Diffuse bone aching and tenderness | Usually painless until a fracture |
| Muscle weakness | Common | Not typical |
| Blood tests | Often abnormal: low vitamin D, raised alkaline phosphatase, low calcium or phosphate | Usually normal |
| Treatment | Vitamin D, calcium, phosphate | Bone-strengthening medicines |
Both conditions show low bone density on DEXA scans, so blood tests help tell them apart. They can occur together.
Causes
Vitamin D deficiency
- little sun exposure: housebound people, covered clothing, northern latitudes, night work
- darker skin, which makes less vitamin D from sunlight
- low dietary intake
- obesity, which traps vitamin D in fat tissue
- older age
Poor absorption
- celiac disease
- inflammatory bowel disease
- bariatric (weight loss) surgery
- chronic pancreatitis and liver disease affecting fat absorption
Kidney and liver disease
- chronic kidney disease reduces activation of vitamin D and causes mineral imbalances
- severe liver disease
Phosphate loss
- inherited conditions such as X-linked hypophosphatemia
- tumor-induced osteomalacia, caused by small tumors that make a phosphate-wasting hormone (FGF23)
- some medicines, including certain IV iron preparations and tenofovir
Medicines
- long-term anti-seizure medicines such as phenytoin and carbamazepine
- some antacids containing aluminum
Symptoms
- bone pain, a dull, deep ache, most often in the lower back, pelvis, hips, legs and ribs, worse with activity and pressure
- muscle weakness, especially in the hips and thighs, causing difficulty rising from a chair or climbing stairs
- a waddling gait
- fractures with little or no trauma
- muscle cramps, numbness or tingling from low calcium
- tiredness
Symptoms are often vague and may be mistaken for arthritis, fibromyalgia or aging.
Diagnosis
- blood tests: 25-hydroxyvitamin D (low), calcium and phosphate (often low), alkaline phosphatase (often high), parathyroid hormone (often high), kidney and liver function
- urine tests for calcium and phosphate loss
- X-rays: may show pseudofractures, typically in the pelvis, ribs, thigh bones and shoulder blades
- bone density scan
- tests for the cause: celiac antibodies, phosphate-regulating hormones in rare cases
- bone biopsy: occasionally needed to confirm the diagnosis
Treatment
- vitamin D: high-dose replacement prescribed by a doctor for several weeks to months, then a maintenance dose
- calcium through diet or supplements
- phosphate supplements for phosphate-wasting conditions, and specific treatments such as burosumab for X-linked hypophosphatemia or tumor-induced osteomalacia
- activated vitamin D (calcitriol) for kidney disease
- treating the underlying cause, such as a gluten-free diet for celiac disease or removing a phosphate-wasting tumor
- physical therapy to rebuild strength and prevent falls
Blood tests are rechecked during treatment, as too much vitamin D can raise calcium to unsafe levels.
Outlook
Most people improve within weeks of starting treatment, with bone pain and weakness easing first. Bone mineralization takes months to recover. Fractures heal, and long-term outlook is good when the cause is treated. Without treatment, ongoing deformity and fractures can occur.
Prevention
- regular safe sunlight exposure, balanced with skin cancer prevention
- foods with vitamin D: oily fish, egg yolks, fortified milk and cereals
- supplements for people at higher risk, such as older adults, those with darker skin, limited sun, or malabsorption
- monitoring in people after bariatric surgery or on long-term anti-seizure medicines
Frequently asked questions
What are the symptoms of osteomalacia?
The main symptoms are aching bone pain, especially in the lower back, pelvis, hips and legs, muscle weakness that makes climbing stairs or rising from a chair difficult, a waddling walk, and fractures after minor trauma. Muscle cramps and tingling can occur if calcium is low.
What is the difference between osteomalacia and osteoporosis?
Osteomalacia is soft bone caused by poor mineralization, usually from lack of vitamin D, and causes bone pain and weakness. Osteoporosis is thin bone that is normally mineralized, often painless until a fracture. Blood tests help tell them apart.
Can osteomalacia be cured?
Yes, in most cases. When caused by vitamin D deficiency, it usually resolves with vitamin D and calcium supplements over several months. Other causes, such as kidney disease or phosphate-wasting conditions, need specific treatment.
How long does it take to recover from osteomalacia?
Bone pain and muscle weakness often start to improve within a few weeks of treatment. Full bone healing and normal mineralization can take 6 months or longer, and maintenance treatment may be needed to prevent recurrence.
Sources
This guide was written from current patient and clinical guidance, including:
- MedlinePlus: Osteomalacia
- NIH Office of Dietary Supplements: Vitamin D fact sheet
- Endocrine Society: Clinical practice guideline on vitamin D
- Mayo Clinic: Osteomalacia
- Merck Manual Professional Version: Osteomalacia and rickets