The World Health Organization established the diagnostic framework for osteoporosis that doctors worldwide still use today. Published formally in WHO Technical Report 921 in 2003, these guidelines define osteoporosis through bone mineral density measurements, set specific thresholds for diagnosis, and introduced a fracture risk tool that shapes treatment decisions. Here’s what those guidelines mean in practical terms.
The T-Score System
The WHO’s most widely used contribution to osteoporosis care is a simple number called a T-score. When you get a bone density scan (a DEXA scan), the machine compares your bone mineral density to that of a healthy 30-year-old, the age when bones are at their strongest. The result is your T-score, and the WHO divides it into three categories:
- Normal: T-score of -1.0 or higher
- Osteopenia (low bone density): T-score between -1.0 and -2.5
- Osteoporosis: T-score of -2.5 or lower
A fourth category, severe osteoporosis, applies when someone has a T-score of -2.5 or lower and has already had a fracture from minimal trauma. These cutoffs aren’t arbitrary. They were chosen because fracture risk rises significantly below each threshold, and they give doctors a consistent way to compare bone health across populations.
Who Should Be Screened
The WHO guidelines don’t prescribe a single global screening schedule, so individual countries have developed their own based on the WHO’s diagnostic criteria. In the United States, the Preventive Services Task Force recommends bone density screening for all women aged 65 and older. Postmenopausal women younger than 65 should be screened if they have one or more risk factors for osteoporosis, including low body weight, a parent who fractured a hip, smoking, or heavy alcohol use. These recommendations apply to adults 40 and older who don’t already have a known osteoporosis diagnosis or history of fragility fractures.
For men, the evidence is less clear. The U.S. task force currently says there isn’t enough data to recommend routine screening in men, though many clinicians still order scans for men with significant risk factors like long-term steroid use or conditions known to weaken bone.
FRAX: The WHO Fracture Risk Tool
One of the most important tools to come out of the WHO’s osteoporosis work is FRAX, a calculator that estimates your 10-year probability of breaking a hip or having another major fracture. FRAX matters because a T-score alone doesn’t tell the whole story. Two people with the same bone density can have very different fracture risks depending on their age, health history, and habits.
FRAX uses the following risk factors to generate its estimate: age, sex, body mass index, previous fracture history, whether a parent fractured their hip, current smoking status, recent use of glucocorticoid medications (like prednisone), rheumatoid arthritis, other conditions that cause secondary bone loss, and consuming three or more alcoholic drinks per day. You can enter your bone density score if you have one, but FRAX can also calculate risk without it.
The practical impact of FRAX is clearest for people with osteopenia. If your T-score falls between -1.0 and -2.5, you don’t automatically need medication. But if your FRAX score shows a 10-year hip fracture risk of 3% or higher, or a major osteoporotic fracture risk of 20% or higher, treatment with medication is generally recommended. People with lower fracture risk typically manage with lifestyle changes alone.
How Common Osteoporosis Is Globally
Using the WHO’s T-score criteria, a large systematic review found that roughly 1 in 5 people worldwide (19.7%) have osteoporosis, and about 40% have osteopenia. The numbers vary enormously by region, from as low as 4.1% in the Netherlands to 52% in Turkey. Developing countries tend to have higher rates (22.1%) than developed countries (14.5%), likely due to differences in nutrition, screening access, and healthcare infrastructure.
Conditions That Cause Secondary Bone Loss
The WHO framework recognizes that osteoporosis isn’t always a standalone condition. Many diseases and medications can weaken bone independently of aging, and FRAX specifically accounts for this category. Conditions linked to secondary osteoporosis include overactive thyroid or parathyroid glands, rheumatoid arthritis, inflammatory bowel disease (Crohn’s or ulcerative colitis), celiac disease, type 1 diabetes, chronic kidney disease, and chronic liver disease.
Medications are a major contributor. Glucocorticoids like prednisone can cause bone loss even at very low doses. Certain diabetes medications, antiseizure drugs, proton pump inhibitors for acid reflux, and some antidepressants have also been associated with reduced bone density. Bariatric surgery, HIV infection and its treatments, and organ transplants all carry elevated risk as well. If you have any of these conditions or take these medications, your doctor may recommend earlier screening regardless of your age.
Calcium, Vitamin D, and Nutrition
Adequate calcium and vitamin D intake forms the foundation of the WHO’s prevention recommendations. Adults over 50 generally need 1,000 to 1,200 mg of calcium per day, with a ceiling of 2,000 mg to avoid complications like kidney stones. The recommended vitamin D intake for most adults is 600 international units (15 micrograms) daily, though many clinicians suggest higher amounts for people already diagnosed with low bone density.
Food sources are preferable to supplements when possible. Dairy products, fortified plant milks, leafy greens, and canned fish with bones all contribute meaningful calcium. Vitamin D is harder to get from food alone, which is why supplements are common, especially for people who get limited sun exposure.
Exercise for Bone Health
Physical activity is a core part of osteoporosis prevention and management. Current exercise guidelines for people with or at risk of osteoporosis focus on three types of activity, each targeting bone health differently.
Resistance training (lifting weights or using machines) is recommended two to three days per week. The goal is to start at a moderate intensity and gradually increase the load over time, working at least three major muscle groups per session. Programs lasting three to twelve months show measurable benefit.
Impact exercises like jumping, skipping rope, or drop landings stimulate bone formation through the force of landing. These are recommended two to three days per week, with 10 to 50 jumps per session. At least six months of consistent practice is needed to see bone density improvements. If you already have osteoporosis or have had fractures, high-impact exercises may not be appropriate, and lower-impact alternatives like brisk walking or stair climbing are safer options.
Weight-bearing aerobic exercise, including walking, stair climbing, and cycling, should be done at least three days per week for 20 minutes or more per session at a moderate intensity. This type of exercise supports bone maintenance and also improves balance, which reduces fall risk.
When Osteopenia Needs Treatment
One of the most common questions about the WHO guidelines is what to do with a diagnosis of osteopenia. The answer depends almost entirely on your overall fracture risk, not just the T-score itself. For people with osteopenia and low-to-moderate fracture risk, the standard approach is nonpharmacologic: regular weight-bearing exercise, quitting smoking, ensuring adequate calcium and vitamin D, and limiting alcohol. No medication is needed.
For those with osteopenia and high fracture risk (determined by FRAX or the presence of other risk factors), medication becomes part of the conversation. This distinction is one of the WHO framework’s most useful contributions. It prevents both overtreatment of people who are unlikely to fracture and undertreatment of people whose bone density looks only mildly low but whose overall risk profile is concerning.