Bone Density Classification and Management

Diagnostic Classification

The World Health Organization (WHO) criteria state that a T-score greater than -2.5 indicates the patient does not have osteoporosis, and falls into either the normal bone density range (T-score > -1.0) or osteopenia/low bone mass range (T-score between -1.0 and -2.5) 1, 2
The WHO established diagnostic thresholds, including normal BMD (T-score > -1.0), osteopenia (T-score between -1.0 and -2.5), and osteoporosis (T-score ≤ -2.5) 1, 2
The diagnostic classification is based on the lowest T-score from any of the recommended DXA measurement sites (lumbar spine, femoral neck, total hip, or one-third radius) 2

A T-score > -1.0 indicates normal bone mineral density with minimal increased fracture risk, and routine monitoring rather than immediate intervention is appropriate 2, 3
For patients with osteopenia (T-scores between -1.0 and -2.5), the FRAX tool should be used to calculate 10-year fracture probability, which incorporates hip BMD measurement, age, gender, height, weight, family history of hip fracture, current smoking status, glucocorticoid use, and rheumatoid arthritis 1
Approximately 40-50% of patients with inflammatory bowel disease fall into the osteopenia category, and 50% of fragility fractures occur in postmenopausal women with T-scores greater than -2.5 (in the osteopenic range) 4, 5

The National Osteoporosis Foundation recommends pharmacologic treatment for patients with osteopenia when FRAX calculations show either a 10-year hip fracture probability ≥3% or a 10-year major osteoporotic fracture probability ≥20% 1
Non-pharmacologic interventions for all patients with T-scores > -2.5 include weight-bearing exercise, calcium intake of at least 1,200 mg/day, and vitamin D supplementation of 800-1,000 IU/day 1, 3, 6
Pharmacologic treatment is not automatically indicated for T-scores > -2.5 unless FRAX criteria are met, or there is a personal history of fragility fracture after age 50 1, 3

For premenopausal women and men under age 50, Z-scores (comparison to age-matched peers) are preferred over T-scores for assessment, and a Z-score ≤ -2.0 suggests bone density below expected range for age 2
When repeating BMD measurements, ensure testing is performed on the same DXA scanner using identical protocols, as vendor differences prohibit direct comparison unless cross-calibration has been performed 3, 5