Serum cholesterol was centrally determined by a modified, semi-automated Abell-Kendall method at the Lipid Standardization Laboratory of the Communicable Disease Center, U.S. Public Health Service, Atlanta, Georgia. The standard error of measurement for blind duplicates, randomized over six days, ranged from 2.7 to 3.0 mg./dl., after repeating the analysis of samples whose duplicates differed by more than 9 mg./dl. Serial analyses of specimens from stock serum pools showed a pooled standard deviation of 3.5 mg./dl., and no systematic trend over time. These data demonstrate the feasibility of obtaining consistent high quality serum cholesterol analyses in a national cooperative study through a central laboratory.
Fatty acid composition of red blood cells, adipose tissue, and cholesterol esters was analyzed locally in three participating laboratories by gas liquid chromatography. At all three laboratories, analyses were confined to the peaks corresponding to palmitate, stearate, oleate, and linoleate; these were calibrated by comparing with N.I.H. standard mixture D chromatographed on the same day.
Triglycerides were measured locally in two participating laboratories, on fasting plasma or randomly collected serum "clarified" by preliminary centrifugation. Inter-laboratory comparison of analyses of fasting serum yielded a mean difference of 2.8 mg./dl., and a standard error of measurement between the laboratories of 14 mg./dl.
Diet-Heart foods were analyzed by the Woodson-Tenent Laboratories, Memphis, Tennessee, for water, total fat, protein, ash, cholesterol, and fatty acid distribution.
- © 1968 American Heart Association, Inc.