Osteomalacia: symptoms, causes, tests and treatment

The NHS lists symptoms of osteomalacia in adults that overlap with rickets in children. NICE CKS says it may present with lower back pain, bone pain in the shoulder, ribs, pelvis or legs, muscle pain and weakness, a waddling gait and impaired physical function.

• Pain in the back, shoulders, ribs, pelvis or legs.

• Changes in how you walk, not wanting to walk much or tiring more easily when walking.

• Difficulty climbing stairs or getting out of a chair because of weak muscles.

• Tingling, cramping or twitching of muscles.

• Breaking bones more often or after a minor accident, especially the hips, lower back and feet.

Bone is living tissue that is constantly laid down and remodelled. For new bone to harden it needs minerals, mainly calcium and phosphate, and vitamin D regulates how much of them the body absorbs and keeps. NICE Clinical Knowledge Summaries describes vitamin D as a fat-soluble vitamin that regulates calcium and phosphate balance and is therefore vital for musculoskeletal health. When there is not enough, the bone matrix stays soft.

The NHS defines the two linked conditions by age: rickets is where a child’s bones become weak and soft, and in adults it is called osteomalacia. It is usually caused by not getting enough vitamin D or calcium. NICE CKS lists osteomalacia as a complication of vitamin D deficiency, alongside osteoporosis, falls and fragility fractures.

The NHS lists vitamin D and calcium supplements, a healthy balanced diet and spending more time outside with the sun on the skin as treatments for rickets and osteomalacia. If the bones have been deformed, for example bowed legs, further treatment is needed and some people need surgery.

NICE CKS says that people needing rapid treatment are prescribed a fixed loading dose of vitamin D followed by maintenance therapy, while those needing less urgent treatment are prescribed maintenance therapy. It also advises assessing dietary calcium and the need for calcium supplements and arranging follow-up to recheck serum calcium and vitamin D when clinically indicated. Specialist advice or referral is advised if someone has a condition predisposing to high calcium, a malabsorption disorder, kidney stones or severe kidney or liver disease. Doses are set by the prescriber and are not given here.

Supplements should not be self-escalated. The NHS vitamin D page warns that taking too much over a long period can cause calcium to build up in the body, weakening bones and damaging the kidneys and heart, and says adults should not take more than 100 micrograms (4,000 IU) a day without medical advice. That page was last reviewed in 2020, so doctors may apply newer local guidance.

The NHS says rickets and osteomalacia are usually caused by low levels of vitamin D and calcium. Our bodies make vitamin D when skin is exposed to summer sunlight, but we cannot make enough between September and March. Calcium comes from foods such as milk, cheese, yoghurt and green leafy vegetables, and a poor diet may not supply enough.

NICE CKS lists the risk factors for vitamin D deficiency: being aged 65 or over, having low or no sun exposure (covering the skin, or being housebound), darker skin pigmentation, malabsorption disorders or weight-loss surgery, severe liver or end-stage kidney disease, certain drugs, pregnancy or breastfeeding, and obesity. The NHS vitamin D page notes that people with dark skin, such as African, African-Caribbean or south Asian backgrounds, may not make enough vitamin D from sunlight.

If osteomalacia is caused by another condition, the NHS says treating that condition helps. Rarer causes need specialist investigation, and this site has a separate page on tumour-induced osteomalacia.

The NHS says that when a GP suspects osteomalacia they check vitamin D and calcium levels, which may include blood tests and testing a sample of urine. They may refer to a specialist for tests such as X-rays and bone scans. NICE CKS says assessment of vitamin D deficiency by checking serum 25-hydroxyvitamin D should be arranged when there are musculoskeletal symptoms that could be due to it, when osteomalacia or osteoporosis is suspected, and in known bone disease where the deficiency must be corrected before specific treatment.

The CKS thresholds in the table give a sense of what the blood result means. Your own result, together with symptoms, calcium, kidney function and other bloods, is what the clinician interprets.

The NHS advice is to take a vitamin D supplement, especially if you are over 65, pregnant or breastfeeding, eat a balanced diet, and try to get outside without sunscreen for 15 minutes two or three times a week between late March and September, which may need to be more often with brown or black skin. In the UK it also says to spend time in the shade when the sun is at its strongest, between 11am and 3pm from late March to September, so skin is not damaged.

On supplements, the NHS vitamin D page says everyone should consider a daily 10 microgram supplement during autumn and winter, and that people at higher risk, including those who are rarely outdoors, who cover most of their skin or have dark skin, should consider taking it all year. NICE CKS gives 400 IU a day (the same quantity) for adults with risk factors throughout the year and for other adults, particularly in autumn and winter.

The sources reviewed here do not give a precise timescale for recovery, but treatment aims to correct the deficiency, and the NHS notes that deformity that has already developed, such as bowed legs, may need further treatment. NICE CKS says follow-up blood tests should recheck calcium and vitamin D when clinically indicated.

The NHS says to see a GP if you think you or your child might have rickets or osteomalacia. It lists breaking bones more often or after a minor accident, pain in the back, shoulder, ribs, pelvis or legs, and weak muscles as symptoms, so a broken bone after a minor fall or new pain that makes walking difficult is a reason to see your GP promptly.

On the NHS, the first step is a GP appointment where vitamin D and calcium are checked by blood tests, with a urine sample if needed, and referral for X-rays or bone scans if a specialist is involved. NICE CKS advises specialist advice or referral if someone has a condition predisposing to high calcium, a malabsorption disorder, kidney stones or severe kidney or liver disease.

You can also arrange a vitamin D blood test privately. Whichever route you take, share the result with your GP, because treatment doses and follow-up depend on the full picture of symptoms, calcium and kidney function.