From the Guidelines
Bone mineral density testing of the hip in young patients is generally not recommended as a routine screening measure unless specific risk factors are present, and when performed, should be interpreted using Z-scores rather than T-scores, with Z-scores below -2.0 considered "below expected range for age" and potentially warranting intervention 1.
Key Considerations
- Young patients, typically under 50, should only undergo hip BMD testing if they have conditions that increase fracture risk, such as chronic steroid use, hyperparathyroidism, malabsorption disorders, hypogonadism, or a history of fragility fractures.
- For at-risk young patients, dual-energy X-ray absorptiometry (DXA) scanning of the hip is the preferred method, as it provides valuable prognostic information about fracture risk and responds differently to various interventions compared to other skeletal sites 1.
- The International Society for Clinical Densitometry (ISCD) recommends using Z-scores in children, adolescents, premenopausal women, and men under the age of 50 years, with a Z-score ≤ -2.0 defined as "bone mineral density below the expected range for age" 1.
Treatment Approaches
- Treatment approaches for young patients with low BMD typically focus on addressing underlying causes, ensuring adequate calcium (1000-1200 mg daily) and vitamin D (600-800 IU daily) intake, promoting weight-bearing exercise, and avoiding smoking and excessive alcohol.
- Pharmacologic therapy is generally reserved for those with fragility fractures or very low BMD with significant risk factors, as the benefits and risks of treatment should be carefully weighed in this population 1.
Risk Factors
- Certain risk factors, such as cranial or spinal irradiation, total body irradiation, and corticosteroid use, may increase the risk of developing weak bones in young patients, highlighting the importance of individualized assessment and monitoring 1.
From the FDA Drug Label
The treatment differences in BMD at 3 years were 8. 8% at the lumbar spine, 6.4% at the total hip, and 5. 2% at the femoral neck. The treatment differences in BMD at 1-year were 4.8% (+0.9% placebo, +5.7% Prolia; (95% CI: 4.0,5.6); p < 0.0001) at the lumbar spine, 2.0% (+0.3% placebo, +2.4% Prolia) at the total hip, and 2.2% (0.0% placebo, +2. 1% Prolia) at femoral neck.
The bone mineral density of the hip in patients treated with denosumab increased by 6.4% at 3 years and by 2.0% at 1-year compared to placebo. However, the absolute bone mineral density values are not provided in the label. 2
From the Research
Bone Mineral Density of the Hip in Young Patients
- The study 3 found that hip fracture in patients under age 50 is rare, and is often not attributable solely to the energy of injury.
- The mean age at the time of injury was 39, and bone mineral density by QCT was below the mean for age in 90% of the patients.
- However, this study does not provide direct information on the bone mineral density of the hip in young patients, as it focuses on trabecular bone mineral density in the lumbar spine.
- Other studies 4, 5, 6, 7 provide information on bone mineral density in older patients or patients with osteoporosis, but do not specifically address the bone mineral density of the hip in young patients.
Related Studies
- A study 4 found that denosumab treatment significantly increased lumbar and hip bone mineral density in patients who were unresponsive to bisphosphonates.
- Another study 5 found that optimal serum 25 (OH) vitamin D concentration may lead to further reduction in bone loss at the hip in patients on bisphosphonates.
- A study 6 found that calcium and vitamin D supplementation with denosumab treatment is beneficial to enhance bone mineral density in postmenopausal patients with osteoporosis and rheumatoid arthritis.
- A meta-analysis 7 found that sequential treatment with bisphosphonate-denosumab is associated with higher lumbar spine bone mineral density gain, but does not provide conclusive evidence on the effect on hip bone mineral density.