Medicine chapters
Osteoporosis (screening and treatment)
What osteoporosis is, who should be screened with DXA and FRAX, how to read T- and Z-scores, and how to prevent fractures with lifestyle measures, calcium and vitamin D, bisphosphonates, denosumab and teriparatide.
- Osteoporosis is low bone mass with damaged micro-architecture, so bones break after minor trauma (spine, wrist, hip); it causes no symptoms until a fracture.
- DXA is the gold standard: T-score of −2.5 or lower = osteoporosis, −1 to −2.5 = osteopenia; treatment is guided by overall fracture risk (FRAX) and previous fragility fracture, not BMD alone.
- First-line drugs are oral bisphosphonates (alendronate weekly, taken fasting and upright), with calcium and vitamin D; alternatives are zoledronate, denosumab and the bone-building teriparatide.
On this page
Overview
Osteoporosis is a disease of low bone mass and weakened bone architecture that makes bones fragile and prone to break with little or no trauma (a fragility fracture, such as a fall from standing height). It is silent until a fracture happens.
It matters because hip and vertebral fractures cause pain, disability, loss of independence and death in older people. About 1 in 2 women and 1 in 5 men over 50 will have an osteoporotic fracture in their remaining life.
Definition (WHO, by DXA)
DXA measures bone mineral density (BMD) at the lumbar spine and hip. The result is compared with a reference:
- T-score = number of standard deviations from the mean of healthy young adults.
- Z-score = number of standard deviations from people of the same age and sex.
| T-score | Category |
|---|---|
| Above −1.0 | Normal |
| Between −1.0 and −2.5 | Osteopenia (low bone mass) |
| −2.5 or lower | Osteoporosis |
| −2.5 or lower plus a fragility fracture | Severe (established) osteoporosis |
Patient BMD 0.70 g/cm²; young adult mean 1.00 g/cm²; SD 0.12
T = (0.70 − 1.00) ÷ 0.12 = −2.5 → osteoporosis
Use T-scores in postmenopausal women and men aged 50 or over. In premenopausal women, men under 50 and children, use the Z-score; a Z-score of −2.0 or below is "low for age" and should prompt a search for a secondary cause.
Pathogenesis
- Bone mass peaks at 20–30 years. The peak depends mostly on genes, plus nutrition, sex hormones and exercise.
- After about 40, bone is slowly lost in both sexes. Women lose bone fast for 5–10 years after the menopause, because oestrogen deficiency increases osteoclast activity and perforates trabeculae.
- The basic fault: bone resorption by osteoclasts exceeds formation by osteoblasts.
- Glucocorticoids reduce bone formation and increase resorption; fracture risk rises within 3 months of starting them.
Risk factors
| Type | Examples |
|---|---|
| Non-modifiable | Age, female sex, White or Asian ethnicity, family history of hip fracture, previous fragility fracture, early menopause |
| Lifestyle | Low body mass index, smoking, excess alcohol, low calcium intake, vitamin D deficiency, immobility, falls |
| Endocrine | Hypogonadism (both sexes), Cushing syndrome, hyperthyroidism (or too much thyroxine), hyperparathyroidism, diabetes |
| Other diseases | Rheumatoid arthritis, malabsorption (coeliac disease, inflammatory bowel disease), chronic liver and kidney disease, COPD, myeloma, anorexia nervosa |
| Drugs | Glucocorticoids (most important), heparin, anticonvulsants, aromatase inhibitors, androgen deprivation (GnRH analogues), thiazolidinediones, proton pump inhibitors, ciclosporin |
The single strongest risk factor for a future fracture is a previous fragility fracture. Many fractures happen in women whose T-score is better than −2.5, so age and other risks matter as much as BMD.
Clinical features
- No symptoms until fracture.
- Vertebral fractures: sudden back pain after minimal strain, but about two in three are silent; loss of height, kyphosis ("dowager's hump"), protuberant abdomen, breathlessness.
- Colles' (distal radius) fracture: fall on an outstretched hand; often the first warning sign in women in their 50s and 60s.
- Hip (proximal femur) fracture: older people falling sideways; high mortality.
A low-trauma fracture in an older person can also be due to metastases or myeloma. Check for these before labelling it osteoporosis.
Investigations
Blood tests
In primary osteoporosis, serum calcium, phosphate and alkaline phosphatase are normal (ALP may rise briefly after a fracture).
| Condition | Calcium | Phosphate | ALP |
|---|---|---|---|
| Osteoporosis | Normal | Normal | Normal |
| Osteomalacia | Low or normal | Low | High |
| Paget disease | Normal | Normal | Very high |
| Primary hyperparathyroidism | High | Low | Normal or high |
Screen for secondary causes, especially in men and in younger patients: full blood count, ESR, renal and liver function, calcium, 25-hydroxyvitamin D, TSH, testosterone (men), protein electrophoresis, coeliac antibodies, and cortisol tests if Cushing syndrome is suspected.
Imaging
- DXA (dual-energy X-ray absorptiometry): the gold standard; low radiation, measures spine and hip. Spinal values can be falsely high in the elderly because of osteophytes and collapsed vertebrae.
- Vertebral fracture assessment (a lateral spine image during DXA) or a lateral spine X-ray to find silent vertebral fractures. A vertebral fragility fracture means treatment is needed whatever the T-score.
- Plain X-rays show fractures; reduced density on X-ray is only a rough clue and needs DXA.
Screening: who should have a DXA and risk assessment?
Approach: assess fracture risk in everyone at risk, then use DXA when it will change management. Kumar lists DXA for:
- Women aged 65 and over, men aged 70 and over.
- Anyone with a fragility fracture.
- Younger women and men with risk factors (e.g. early menopause, long-term steroids, low BMI, rheumatoid arthritis).
- Monitoring of patients on treatment.
FRAX
FRAX combines age, sex, BMI, prior fracture, parental hip fracture, smoking, alcohol, glucocorticoid use, rheumatoid arthritis, secondary causes and (optionally) femoral neck BMD to give the 10-year probability of a major osteoporotic fracture and of a hip fracture.
One widely quoted rule (US guidance, cited in Kumar): treat if the 10-year major fracture risk is 20% or more, or the hip fracture risk is 3% or more. Thresholds vary by country and cost.
Treatment is guided by fracture risk, not by BMD alone. Offer treatment to anyone who has already had a fragility fracture or whose T-score is −2.5 or below.
Management
1. General measures (everyone)
- Calcium about 800–1200 mg a day and vitamin D about 400–800 IU a day, ideally from diet and sunlight; supplement if intake or vitamin D levels are low. Correct vitamin D deficiency before starting a bisphosphonate.
- Weight-bearing exercise (e.g. 30 minutes three times a week) and balance training.
- Stop smoking, limit alcohol, keep a healthy weight.
- Prevent falls: review sedatives and blood pressure drugs, check vision, home safety, physiotherapy; hip protectors in care homes (if worn).
In Pakistan, vitamin D deficiency is very common (covered dress, indoor lifestyle) and DXA is not available everywhere; follow current national and local guidance.
2. Drug treatment
| Drug | How it works | How it is given | Key points |
|---|---|---|---|
| Alendronate, risedronate (oral bisphosphonates) | Bind to bone mineral and inhibit osteoclasts | Once weekly tablet | First-line; reduce vertebral, non-vertebral and hip fractures |
| Ibandronate | Bisphosphonate | Monthly tablet (or 3-monthly IV) | Hip benefit less certain |
| Zoledronate (zoledronic acid) | Bisphosphonate | Once-yearly IV infusion | If oral drugs cannot be taken; after a hip fracture |
| Denosumab | Monoclonal antibody against RANKL, blocks osteoclast formation | Subcutaneous every 6 months | Similar fracture reduction to bisphosphonates; usable in poor renal function; effect lost quickly when stopped, so follow with another drug |
| Teriparatide | Recombinant PTH (1–34); intermittent dosing builds bone (anabolic) | Daily subcutaneous injection for up to 24 months | Severe disease, multiple vertebral fractures, very low BMD, failure of other drugs; follow with an anti-resorptive |
| Raloxifene (SERM) | Oestrogen-like on bone, blocks oestrogen in breast and uterus | Daily tablet | Vertebral fractures only; venous thromboembolism, hot flushes, leg cramps |
| HRT | Oestrogen | Daily | Only for early postmenopausal women who also have menopausal symptoms |
| Calcitriol, calcitonin, strontium | Various | Various | Rarely used; strontium linked to cardiovascular and clot risks |
How to take an oral bisphosphonate
- On waking, on an empty stomach, with a full glass of plain water.
- Stay upright (sitting or standing) and take no food, drink or other medicines for at least 30 minutes.
"Empty, Water, Upright, Wait" for alendronate.
Side effects of bisphosphonates
- Oesophagitis and upper gut upset (worse if the rules are not followed); avoid in oesophageal stricture or achalasia.
- Osteonecrosis of the jaw: rare, mainly with high-dose IV use in cancer and poor dental hygiene; do dental work first.
- Atypical femoral (subtrochanteric) fractures with long use: thigh or groin pain should be investigated.
- Acute phase reaction (flu-like illness) after IV zoledronate.
- Avoid or use with care in severe CKD (stage 4–5); correct hypocalcaemia first.
Drug holiday: reassess after about 5 years of oral bisphosphonate (3 years for zoledronate in many guidelines). Continue only in those still at high risk (for example vertebral fractures and a femoral neck T-score still below −2.5).
Oral bisphosphonates (alendronate, risedronate) are first-line for most patients; IV zoledronate, denosumab or teriparatide are used when tablets cannot be taken, fail, or disease is severe.
Denosumab is not like a bisphosphonate: it does not stay in bone. Stopping it without a follow-on drug can cause rapid bone loss and multiple vertebral fractures.
Special groups
Glucocorticoid-induced osteoporosis
- Assess anyone expected to take oral steroids for at least 3 months, whatever the dose.
- Postmenopausal women, men over 50 and anyone with a previous fragility fracture should start bone protection (usually a bisphosphonate) straight away, without waiting for DXA.
- Use the lowest steroid dose for the shortest time; give calcium and vitamin D.
Men
Look hard for secondary causes (hypogonadism, alcohol, steroids, myeloma). Alendronate, risedronate, zoledronate, denosumab and teriparatide can be used; give testosterone if hypogonadal.
Vertebral fracture pain
Analgesia, short rest then early mobilisation and physiotherapy; calcitonin can help pain briefly; vertebroplasty or kyphoplasty in selected persistent cases. Hip fractures need early surgery and mobilisation, then bone treatment.
Expect: the WHO T-score definition and osteopenia range; T-score versus Z-score; normal calcium, phosphate and ALP in osteoporosis versus osteomalacia and Paget disease; the main risk factors, especially steroids, early menopause, low BMI and previous fracture; DXA as the gold standard; FRAX thresholds; how to take alendronate; bisphosphonate side effects (oesophagitis, jaw osteonecrosis, atypical femoral fracture); denosumab as a RANKL antibody with rebound on stopping; teriparatide as the anabolic option; raloxifene and clots; bone protection for patients on long-term steroids.
Quick revision
- T-score ≤ −2.5 = osteoporosis; −1 to −2.5 = osteopenia; Z-score in the young and premenopausal.
- Silent until fracture: vertebra, wrist, hip; two-thirds of vertebral fractures are silent.
- Bloods normal; check for secondary causes, especially in men.
- DXA: women 65+, men 70+, fragility fracture, younger with risk factors; FRAX for 10-year risk.
- Calcium, vitamin D, exercise, stop smoking, prevent falls.
- First line: weekly alendronate or risedronate (empty stomach, water, upright 30 minutes).
- Others: yearly IV zoledronate, 6-monthly denosumab (rebound if stopped), daily teriparatide (anabolic), raloxifene (spine only, VTE).
- Steroids for 3 months or more: protect bone early.
Written by The House Job from standard references (Kumar and Clark's Clinical Medicine).
FAQ
Does osteoporosis cause bone pain?
Not by itself; pain comes from the fractures it causes, most often in the spine, wrist or hip.
What is the difference between osteoporosis and osteomalacia?
Osteoporosis is a loss of normally mineralised bone with normal blood tests, whereas osteomalacia is poor mineralisation from vitamin D lack, with low calcium and phosphate and a high ALP.
Why must alendronate be taken with water on an empty stomach?
Food, milk and other drinks block its absorption, and staying upright with plenty of water stops the tablet irritating the oesophagus.
Can a person with a normal T-score need treatment?
Yes. Someone with a vertebral fragility fracture or a high FRAX risk may need treatment even if the T-score is above −2.5.
Why is teriparatide followed by another drug?
Its bone gains fade after it stops, so an anti-resorptive such as a bisphosphonate is given afterwards to keep the new bone.