ABSTRACT. The Longitudinal Aging Study Amsterdam (LASA) is an ongoing prospective cohort study in a representative sample of Dutch older persons. In previous LASA studies, lower serum 25-hydroxyvitamin D (25(OH)D) values, as assessed by a competitive protein binding assay or radioimmunoassay, have been associated with decreased physical functioning, falls and fractures. Recently, serum 25(OHD) values in LASA were standardized using the Vitamin D Standardization Program (VDSP) protocol as part of the European ODIN project. In the current manuscript, the influence of standardizing serum 25(OH)D values will be discussed using the associations with physical functioning, falls and fractures as examples.
