Overnight fasting blood samples were drawn by venipuncture to
measure serum total cholesterol, HDL cholesterol, and triglycerides.
Blood specimens were processed at the field center and shipped by
air to the central clinical laboratory at the Department of Population
Genetics at Fuwai Hospital of the Chinese Academy of Medical
Sciences in Beijing, where the specimens were stored at 70°C until
laboratory assays could be performed. This laboratory participates in
the Lipid Standardization Program of the US Centers for Disease
Control and Prevention. Total cholesterol, HDL cholesterol, and
triglycerides were analyzed enzymatically on a Hitachi 7060 Clinical
Analyzer (Hitachi High-Technologies Corp) by use of commercial
reagents.14 Serum control pools were obtained from Solomon Park
Research Laboratories. LDL cholesterol levels were calculated by
use of the Friedewald equation for the participants who had triglyceride
levels 400 mg/dL: LDL cholesteroltotal cholesterolHDL
cholesteroltriglycerides/5.15
Se