What Is Osteoporosis: Risk Factors, Prevention, and Treatment

What Is Osteoporosis?

Osteoporosis is a skeletal disease characterized by low bone mass and deterioration of bone tissue, leading to increased bone fragility and susceptibility to fracture. The name derives from Latin and Greek roots meaning porous bone, and indeed, under microscopy osteoporotic bone shows enlarged spaces within its spongy inner structure and thinning of the outer cortical layer. The result is bone that is structurally compromised and at high risk of breaking from forces that healthy bone would easily withstand.

Osteoporosis is often called a silent disease because bone loss occurs without symptoms. The condition is typically not discovered until a fracture occurs, often from a minor fall or, in severe cases, from a cough or sneeze. The most common fracture sites are the spine (vertebral compression fractures), hip, and wrist. Hip fractures are especially serious — they are associated with a 20 to 30 percent mortality rate within one year in older individuals and often require surgery and extended rehabilitation.

Globally, osteoporosis affects an estimated 200 million people and causes more than 8.9 million fractures annually. While it affects people of all ages, sexes, and ethnicities, it disproportionately affects postmenopausal women. Women can lose up to 20 percent of their bone density in the five to seven years following menopause, when the bone-protective effects of estrogen are lost.

How Bone Density Is Built and Lost

Bone is living tissue in a constant state of remodeling. Two types of cells govern this process: osteoblasts, which build new bone by depositing collagen and minerals, and osteoclasts, which break down old bone in a process called resorption. In childhood and adolescence, bone formation outpaces resorption, leading to increasing bone density. Peak bone mass is typically reached in the late 20s, after which the balance gradually shifts and resorption begins to exceed formation.

The rate of bone loss accelerates dramatically at menopause when estrogen levels fall. Estrogen normally inhibits osteoclast activity; without it, bone resorption proceeds at an accelerated pace for several years before stabilizing at a slower chronic rate. Calcium and vitamin D are essential for bone formation — calcium provides the mineral content and vitamin D enables its absorption from the gut. Deficiency in either accelerates bone loss.

Mechanical loading through weight-bearing exercise stimulates bone formation by applying stress to the skeleton, signaling osteoblasts to build stronger bone. This is why sedentary individuals and those who are bedridden experience accelerated bone loss. Conversely, athletes who engage in high-impact activities often have greater bone density than age-matched non-athletes.

Risk Factors for Osteoporosis

Risk factors for osteoporosis fall into two categories: fixed and modifiable. Fixed risk factors include age, female sex, family history of osteoporosis or fracture, personal history of fracture, small body frame, and certain ethnic backgrounds (White and Asian individuals are at higher risk). Early menopause (before age 45) and long-term use of corticosteroids, anticonvulsants, or certain cancer treatments are also significant risk factors.

Modifiable risk factors include low calcium and vitamin D intake, physical inactivity, smoking, excessive alcohol consumption (more than two to three drinks daily), low body weight, and chronic conditions such as celiac disease, inflammatory bowel disease, rheumatoid arthritis, and thyroid disorders. Eating disorders that lead to malnutrition and prolonged amenorrhea (absent periods) from excessive exercise or restrictive eating also substantially impair bone development and accelerate loss.

The combination of risk factors is more important than any single factor. Tools such as the FRAX algorithm calculate the 10-year probability of a major osteoporotic fracture based on individual risk profiles, helping clinicians determine when to initiate treatment even before a fracture occurs.

Diagnosis: Bone Density Testing

Osteoporosis is diagnosed using dual-energy X-ray absorptiometry (DXA), a low-radiation imaging technique that measures bone mineral density at the spine and hip. Results are reported as a T-score, which compares the individual's bone density to the average peak bone density of a young healthy adult. A T-score of -1.0 or above is normal; between -1.0 and -2.5 indicates osteopenia (low bone density but not yet osteoporosis); and -2.5 or below indicates osteoporosis.

Screening recommendations vary by organization, but most advise DXA testing for all women aged 65 and older and for younger postmenopausal women with risk factors. Men are typically screened starting at age 70. Repeat DXA testing intervals depend on initial results and treatment status — individuals on therapy are typically rescanned every one to two years, while those with normal or mildly reduced density may not need rescanning for several years.

Additional evaluation may include blood and urine tests to look for secondary causes of bone loss, such as vitamin D deficiency, hyperparathyroidism, hyperthyroidism, or malabsorption conditions. Identifying and treating secondary causes is an important part of osteoporosis management.

Prevention: Building and Protecting Bone

Prevention of osteoporosis ideally begins in childhood and adolescence, the period when the skeleton is most responsive to lifestyle inputs. Adequate calcium intake throughout life is fundamental — recommended amounts are 1,000 mg daily for adults and 1,200 mg for women over 50 and men over 70. Dairy products, fortified plant milks, leafy greens, almonds, and sardines are good dietary sources. Vitamin D, needed to absorb calcium, is obtained through sun exposure and dietary sources including fatty fish and fortified foods; supplementation is often needed, especially in northern latitudes and for those with limited sun exposure.

Weight-bearing and resistance exercise are powerful bone-building tools at any age. Activities that involve impact — walking, jogging, dancing, tennis — and resistance training that loads the skeleton stimulate bone formation. Balance training reduces fall risk, which is as important as bone density in preventing fracture. Tai chi has evidence supporting its effectiveness in improving balance and reducing falls in older adults.

Smoking cessation and limiting alcohol intake reduce bone loss and fracture risk. Fall prevention strategies including home safety modifications, vision correction, medication review for drugs that impair balance, and addressing dizziness are essential components of fracture prevention in older individuals.

Medical Treatment for Osteoporosis

When osteoporosis is diagnosed or fracture risk is elevated, pharmacological treatment is recommended. Bisphosphonates — including alendronate, risedronate, and zoledronic acid — are the most widely prescribed first-line medications. They work by inhibiting osteoclast activity, slowing bone resorption, and have been shown to reduce vertebral and hip fractures by 30 to 70 percent in clinical trials. They are typically taken orally (weekly or monthly) or intravenously (annually).

Denosumab, a monoclonal antibody that blocks a key signal for osteoclast activation, is an alternative for those who cannot tolerate bisphosphonates or need greater potency. It is given by injection every six months. Anabolic agents — teriparatide, abaloparatide, and romosozumab — stimulate new bone formation and are reserved for those with severe osteoporosis or high fracture risk. These are more expensive and typically used for limited periods before transitioning to an antiresorptive therapy.

Hormone therapy for postmenopausal individuals is effective at preventing bone loss and reducing fracture risk, and may be the preferred option when menopausal symptoms are also being treated. Raloxifene, a selective estrogen receptor modulator (SERM), provides bone protection and reduces breast cancer risk in postmenopausal women but is less effective at hip fracture prevention. Treatment decisions are individualized, taking into account fracture risk, comorbidities, medication tolerability, and patient preferences, with regular monitoring to assess response and adjust therapy as needed.