Osteoporosis

What is it?

According to the NIAMS: a bone disease that develops when bone density and mass fall or when bone structure and strength change, raising the risk of fractures. The NHS describes it as a condition that weakens the bones, making them fragile and more likely to break, and that develops gradually over years and is often only diagnosed after a fracture.

The NIAMS states that it is the main cause of fractures in postmenopausal women and older men, and it affects all races with higher rates in white and Asian women. This page's sources do not give specific prevalence figures.

Causes

Bone loss naturally speeds up with advancing age, women lose bone rapidly after menopause because oestrogen falls, and testosterone likewise falls in men (NIAMS, NHS).

Risk factors

Non-modifiable factors (NIAMS): female sex, advancing age, a slim build, white or Asian race, family history of osteoporosis or hip fracture. Modifiable factors: low calcium and vitamin D in the diet, low physical activity, smoking, excessive alcohol, and some medicines (corticosteroids, anti-epileptics, cancer drugs, and proton pump inhibitors).

The NHS adds: taking high-dose steroids for 3 months or more, inflammatory and hormonal diseases and malabsorption, eating disorders, low body mass index, and anti-oestrogen medicines after breast cancer. MedlinePlus adds endocrine and digestive diseases, rheumatoid arthritis and HIV.

Symptoms

The disease is "silent": usually no symptoms until a fracture occurs. Fragile bones break from a minor fall or from ordinary activities such as bending, coughing or sneezing; the most common sites are the wrist, hip and spine. A vertebral fracture may cause severe chronic back pain, loss of height and a stooped posture (NIAMS, NHS).

How is it diagnosed?

Dual-energy X-ray absorptiometry (DXA) is a quick, painless test that needs no surgery, measures bone density in the spine and hip, and is the "most reliable" for diagnosing osteoporosis and predicting fracture risk. Peripheral DXA of the wrist or heel may not reliably predict future fracture, and quantitative ultrasound does not measure density and DXA is needed if there is an abnormality (NIAMS).

The NHS classifies the test result by T-score: above -1 normal, between -1 and -2.5 low bone mass, and below -2.5 osteoporosis. The FRAX tool is used to estimate 10-year fracture risk, and MedlinePlus mentions assessing height, posture, balance and muscle strength.

Treatment

The treatment categories usually used are listed here; this is not a prescription. The doctor chooses the plan according to each person's condition; do not change any medicine or dose without a specialist.

FDA-approved medicines according to the NIAMS: bisphosphonates (slow bone loss), calcitonin and SERMs for postmenopausal women, oestrogen and hormone therapy at the lowest dose for the shortest time, parathyroid hormone analogues (PTH/PTHrP), a RANKL inhibitor and a sclerostin inhibitor for severe cases. The choice of medicine is for the doctor according to fracture risk.

Non-drug: adequate calcium, vitamin D and protein for age (doses are set with the doctor), resistance and balance exercises while avoiding high-impact activities, and fall-prevention measures: removing clutter, improving lighting, installing grab bars, supportive footwear and securing rugs (NIAMS, MedlinePlus).

Follow-up

The doctor recommends monitoring bone density, fracture risk and treatment effectiveness periodically (the NHS mentions seeing a doctor for unexplained fractures or if risk factors are present). This page does not cover specific screening intervals.

Prevention

According to the NIAMS, MedlinePlus and the NHS: weight-bearing and strengthening exercise, a diet rich in calcium and vitamin D, quitting smoking, and cutting down on alcohol. The NHS recommends a daily vitamin D supplement according to UK guidance; guidance varies by country and sun exposure, so ask your doctor about your level.

Common questions