Reference Values for Forearm Bone Mineral Density Berntsen et al. Forearm Bone Mineral Density by Age in 7,620 Men and Women The Tromsø Study, a Population-based Study

Population-based studies of adult forearm bone mineral density (BMD) by age are scarce, and standardized reference values are lacking. In this cross-sectional study, men aged 55–74 years, women aged 50–74 years, and representative 5–10 % samples of remaining age groups between 25 and 84 years living in Tromsø, Norway, were invited for forearm BMD measurement in 1994–1995. The authors measured 3,062 men and 4,558 women (response rate, 78%) by single x-ray absoptiometry at distal and ultradistal forearm sites. Up to age 50, the mean BMD difference was –0.1 % per 1-year age group in both sexes. After age 50, the mean BMD difference per 1-year age group was –0.6 % in men and –1.3 % (distal) and –1.5 % (ultradistal) in women. The BMD by age curve was linear for men throughout senescence, but women had a slope change to –0.7 % (distal) and –0.8% (ultradistal) per 1-year age group from the 65- to 69-year age group. BMD levels and BMD by age association in the general population (n = 7,620) and in the population without bone-threatening diseases or medication (n = 5,179) were similar. Only longitudinal studies can clarify whether cohort effects or longitudinal BMD development patterns explain these cross-sectional results. Am J Epidemiol 2001;153:465–73. bone density; cross-sectional studies; densitometry, X-ray; forearm; men; menopause; reference values; women Received for publication November 22, 1999, and accepted for publication June 22, 2000. Abbreviations: BMD, bone mineral density; ∆BMD, mean BMD dif-ference