Serum albumin and bone mineral density in healthy older men and women: the Rancho Bernardo Study.

Serum albumin has been found to be positively correlated with bone mass in small studies of ambulatory men or women with diagnosed osteoporosis. In this study the relation between serum albumin and bone mineral density (BMD) was examined in 1593 white, community-dwelling men and women aged 50-95 years. BMD was determined using single-photon absorptiometry (SPA) at the ultradistal radius and the midshaft radius, and using dual-energy X-ray absorptiometry (DXA) at the hip and spine. Albumin was measured from a fasting blood sample using the Technicon SMA 12 autoanalyzer. Mean albumin levels in both men and women decreased significantly with increasing age. All but four values were within the normal range (3.5-5.0 g/dl). BMD decreased with increasing age at all sites. In both sexes there was weak positive correlation between serum albumin and BMD in the unadjusted model (Pearson's r values < 0.3, p values < 0.005). After age adjustment, however, the relationship was no longer significant (Pearson's r values < 0.05, p values > 0.18). Men and women were divided into three sex-specific categories--osteoporotic, osteopenic and normal--based on World Health Organization criteria in relation to young adult means (normal, BMD > -1 SD; osteopenia, BMD between -1 SD and -2.5 SD; osteoporosis, BMD < -2.5 SD). Mean albumin values did not differ significantly across the three BMD categories in men or women. BMD levels stratified for albumin levels and calcium supplement status (a marker for osteoporosis awareness) also did not differ. Albumin levels were also not associated with a history of low-trauma fractures. In summary, there was no age-independent association between serum albumin within the normal range and low BMD or fractures in community-dwelling healthy older adults. We conclude that previously reported associations most likely reflect inadequate adjustment for the age-related decrease in albumin levels and the selection of very frail osteoporotic subjects.