Obituary U. doctor who created vitamin D test dead at 59

University endocrinologist John Haddad -- who developed the standard test for vitamin D levels in the blood -- died in Paris on May 22 at the age of 59. He lived in Philadelphia, but family members said Haddad was in Paris for a medical meeting and died of a heart attack. Haddad was associate chairman of research in the department of medicine at the University's School of Medicine, where he had worked since 1980. He is most famous for the vitamin D test he created while working at Washington University in St. Louis in the 1960s, according to his mentor Louis Avioli, director of bone and mineral disease at the Washington University School of Medicine. Avioli explained that vitamin D is normally absorbed from a number of foods and noted that it is often added to milk. But some people are unable to absorb vitamin D and develop diseases as a result. Careful measurement of the amount of vitamin in the blood is crucial. Haddad's test measures natural vitamin D levels by giving patients vitamin D with radioactivity that makes it traceable as it seeks binding sites on protein in the blood. The more natural vitamin D there is already occupying the sites, the less the radioactive substance can bind to the protein. In addition to creating the vitamin D test, Haddad also discovered the link between vitamin D and the immune system. He observed that the protein molecules which bind to vitamin D also play a role in the way the immune system protects the body during trauma. He was co-founder and past president of the American Society for Bone and Mineral Research, and he is credited with increasing awareness of osteoporosis. Haddad was born in New Orleans and received his bachelor's degree from Tulane University in 1958, where he also earned his medical degree in 1962. After graduating from Tulane, he completed his residency at Charity Hospital in New Orleans, playing the saxophone in jazz groups to help pay his costs. Haddad then went on to study endocrinology at the University of Virginia Medical School before joining the faculty of Washington University School of Medicine. He is survived by his wife Julia, his sister Joanne and his two children, Margaret and John.