Calculation of the reference bone mineral density values in North Indian population using phantomless quantitative computed tomography

OBJECTIVE: The objective of the study is to generate reference values of bone mineral density (BMD) in north Indian population using phantomless quantitative computed tomography (QCT). MATERIALS AND METHODS: Bone mineral densities were generated from the computed tomography (CT) scans of 691 patients (390 males and 301 females, ages 11–85 years) who underwent CT of the abdomen or thorax for indications unrelated to bone diseases. The individuals were divided according to age groups from 11–15 to 80–85 years. BMD was calculated by phantomless QCT software by assessing L1 and L2 vertebrae. RESULTS: For females, the maximum BMD was observed for the age group of 21–25 years (144.67 mg/cc). The overall bone loss per year from 26 to 85 years was 1.62 mg/cc. Greater bone loss was seen from ages of 36–55 years which was 2.18 mg/cc. With bone loss per year being 0.99 mg/cc in ages from 26 to 35 years and 1.41 mg/cc from 56 to 85 years. Regression analysis gave a better fit using third order polynomial of age than did a linear regression line. For males, the maximum BMD was observed for the age group of 21–25 years (147.67 mg/cc). The overall bone loss per year from 26 to 85 years was 1.2 mg/cc. Regression analysis gave the best fit using linear regression. CONCLUSION: In the study population, the males show a linear relationship between age and BMD with continuous bone loss after the age of 25 years while females demonstrate a more complex relationship between age and BMD with accelerated bone loss in perimenopausal age group.