Vertebral bone density in Icelandic women using quantitative computed tomography without an external reference phantom.

Vertebral trabecular bone mineral density (BMD) was measured in 187 healthy Icelandic women, age 35-64 years, by quantitative computed tomography (QCT) with the use of internal references (muscle and subcutaneous fat) instead of the traditional external references (phantoms). We found a mean 2.4 mg/cm3 (1.8%) bone loss per year in the age range 35-64 years. There was an accelerated phase (exponential) after menopause, with 4% loss per year for the first 1-5 years after menopause or 5-fold trabecular bone loss compared with the subsequent 11-15 years after menopause. Reproducibility was found to be 1.9%. This method thus compares with traditional QCT measurements and is highly reproducible. We find QCT using internal references a promising method for assessing fracture risk in perimenopausal women and for follow-up in osteoporotic patients.