Lumbar bone mineral content and density measured using a Lunar DPX densitometer in healthy full-term infants during the first year of life.

This cross-sectional study provides values for lumbar spine bone mineral content (BMC) and density (BMD) in 41 healthy full-term born Finnish infants, 19 boys and 22 girls, during the first year of life measured by dual energy X-ray absorptiometry (DXA) using the Lunar DPX densitometer. Lumbar BMC correlated with the weight (r=0.733; P=0.000), length (r=0.677; P=0.000), standardized length (r=0.315; r=0.045) and age at examination (r=0.314; P=0.045), and with the bone area (r=0.736; P=0.000). Infants with < or =-1 SD scores for lengths at examination had significantly lower BMC values [mean (SD); 1.79 (0.66) g] than infants with SD scores above -1 SD [2.27 (0.46) g] (P=0.011). Exclusive breast feeding did not correlate with the lumbar BMC values (r=-0.039; P=0.811). No differences were found in lumbar spine BMC (P=0.097), BMD (P=0.254) and bone area (P=0.094) values between boys and girls. In order to determine the predictive value of the anthropometric measurements on lumbar BMC, stepwise multiple regression analysis were performed, bone area and present weight were the only independent variables which explained 67.6% of the variance in the BMC values. The present cross-sectional data imply that, in healthy term infants, patterns of relative linear growth during the first year of life are related to the lumbar BMC values. In future, careful longitudinal measurements of linear growth are needed to study connections between growth patterns and bone mineral status in infancy.