Osteopenia describes a state of decreased bone mineral density (BMD), in which bone density is below normal but not low enough to be considered osteoporosis.^[1] BMD is correlated with bone strength, which is reduced in osteopenia, increasing the risk of bone fractures (broken bones).^[2][3] In some people, osteopenia may progress to osteoporosis, which further increases the risk of fractures, disability, and death.^[3][1]

A 2022 meta-analysis including participants from 30 different countries estimated the global prevalence of osteopenia to be 40.4%, although rates varied widely between countries and developing countries had the highest prevalence. Postmenopausal women are disproportionately affected by reduced BMD due to reductions in estrogen, but men are also impacted by low BMD. This global meta-analysis reported higher rates of osteopenia in men than in women, but higher rates of osteoporosis in women, indicating that women are more likely than men to progress to osteoporosis.^[4]

Osteopenia, or low bone density, usually does not cause any symptoms. Sometimes the first sign of osteopenia will be a fragility fracture, which is when a bone breaks from an impact that would normally not cause a fracture in a healthy individual (e.g., falling from standing height). However, in many people osteopenia may go unrecognized.^[5]

Osteopenia is diagnosed by measuring BMD at the hip, forearm, or spine. The gold standard test for measuring BMD is a dual-energy x-ray absorptiometry (DEXA) scan, and osteopenia is diagnosed when BMD is 1−2.5 standard deviations below the average BMD for a young, healthy individual of the same sex. When measuring BMD, this is referred to as a T-score, and therefore a T-score between −1 and −2.5 is diagnostic for osteopenia. Similarly, a T-score of −2.5 or lower is diagnostic for osteoporosis.^[5]

After diagnosis, blood tests are used to check levels of calcium, phosphorus, vitamin D, thyroid hormones, parathyroid hormone, and testosterone in men, as well as to assess liver and kidney function. These tests can help identify underlying issues that may be contributing to reduced BMD.^[5][6]

Bone fractures can cause pain, reduce mobility, and create challenges in performing activities of daily living. Fractures of the hip or spine can even increase the risk of death. Therefore, the focus of osteopenia treatment is to prevent fractures and slow or stop the progression to osteoporosis.^[3] Lifestyle modifications are the mainstay of treatment in osteopenia,^[6] These include:

• Regular exercise, including weight-bearing exercises
• Adequate intake of calcium from the diet and/or supplementation
• Prevention of vitamin D deficiency through supplementation and/or sun exposure
• Avoidance of smoking and excessive alcohol consumption
• Addressing underlying health conditions that may contribute to reduced BMD
• Practicing fall prevention strategies (e.g., securing loose carpets; using adequate lighting; wearing properly fitting shoes and clothing)

Maintaining adequate levels of calcium and vitamin D is important for optimizing bone health and preventing fractures and the progression to osteoporosis. Calcium is a key mineral involved in bone formation and the maintenance of bone strength, while vitamin D promotes calcium absorption and helps to regulate bone turnover. If levels of calcium and vitamin D remain inadequate from diet and sunlight exposure, then supplementation is recommended.^[5]

Vitamin K is indirectly involved in the maintenance of healthy bones, and supplementation does seem to reduce markers of bone turnover; however, it’s unclear from the current evidence whether this translates to increases in BMD or a reduced risk of fractures.^[7][8][9]

Soy isoflavones, which are structurally similar to estrogen, may have beneficial effects on menopause-related reductions in BMD. However, more research is needed to clearly establish this effect and to determine the ideal dosage and source of isoflavones (i.e., soy protein or isoflavone extracts). Interestingly, these effects may be mediated in part by the gut microbiota which convert isoflavones into active metabolites.^[10][11][12]

Other supplements, including magnesium and creatine, show some promise in preliminary studies, but more research is needed to confirm their effects.^[13]PMID:34666201]

Diet is an important contributor to bone health. A 2019 meta-analysis of observational studies found that Western dietary patterns, including high consumption of red and processed meats, refined grains, fried foods, and sweets, were associated with an increased risk of low BMD and fractures.^[14] Alternatively, healthy dietary patterns like a Mediterranean diet and those containing more dairy products have been associated with a reduced risk of low BMD and fractures.^[14][15] These healthy dietary patterns provide important nutrients for bone health, including calcium, potassium, B vitamins, magnesium, vitamin D, vitamin K, and vitamin C.^[14][5]

Healthy dietary patterns, including adequate calcium intake in adolescence and throughout the lifespan, are important for attaining adequate peak bone mass between ages 20 and 30, and for minimizing age-related reductions in BMD afterward.^[5]

Medications are generally reserved for people with osteopenia who have a particularly high risk of fractures (as determined by a clinician). People with an osteopenia T-score (−1 to −2.5) and a 10-year fracture risk of 20% or more (measured using tools like the Fracture Risk Assessment Tool, FRAX) may be started on medication to increase bone density.^[5][6] These same medications are used for the treatment of more severe bone loss or osteoporosis. The most commonly used medications are bisphosphonates (risedronate, alendronate, etc.), which reduce bone breakdown; however, prolonged use can increase the risk of atypical fractures of the femur bone, and therefore continuous use is generally limited to 3 to 5 years. Other medications include estrogen and/or progestin hormone-replacement therapies, selective estrogen receptor modulators (raloxifene), calcitonin, teriparatide, and denosumab.^[5][6]

The loss of bone mass with age is a natural process that generally begins after age 30. Bones are in a constant state of remodeling (being built and broken down), and when bone breakdown begins to exceed bone building, gradual reductions in bone density occurs, and over time osteopenia may result.^[6] The rate that bone loss leads to osteopenia is highly dependent on genetics, but it is also influenced by modifiable factors beginning in adolescence including physical activity levels, body mass, nutritional status, and the levels of various hormones. Certain disease states, medications, and lifestyle practices may also contribute to an accelerated loss of bone density.^[5][6]