1. Department of Medical Sciences, Clinical Chemistry, University Hospital , SE 751 85 Uppsala , Sweden
2. Pathology Service, Massachusetts General Hospital , Boston, MA 02114 , USA
3. Reproductive Endocrine Unit, Department of Medicine, Massachusetts General Hospital , Boston, MA 02114 , USA
4. National Institute of Environmental Health Sciences, National Institutes of Health , Research Triangle Parc, NC 27709 , USA