Authors
	Paul L.A. van Daele, MD is resident in Internal Medicine at the Department of Internal Medicine III, University Hospital "Dijkzigt", Rotterdam, The Netherlands. From 1992–1996 he worked as a research fellow at the department of Epidemiology and Biostatistics, Erasmus University Medical School, Rotterdam. He wrote his thesis on the ultrasonic evaluation of osteoporosis and the value of biochemical markers of bone turnover in the prediction of osteoporotic fractures. Currently he is involved in studies on endocrine determinants of osteoporosis. Huibert A. P. Pols, MD is Professor of Medicine at the Department of Internal Medicine III, Erasmus University Medical School, Rotterdam, The Netherlands. During the 15 years his research was focused on calcium and bone metabolism, especially the mechanisms of action of vitamin D and metabolic bone diseases. Since 1992 he is also involved in epidemiogical research as principal investigator of the Rotterdam Study (endocrine determinants of diseases in the elderly). He was one of the organizers of the World Congress on Osteoporosis 1996 in Amsterdam. He is also a member of the board of the Dutch Endocrine Society. His current interests are focused on the genetic aspects of osteoporosis.