Apolipoprotein B and AI distributions in the United States, 1988-1991: results of the National Health and Nutrition Examination Survey III (NHANES III).

Serum apolipoproteins (apo) B and AI were measured in a probability sample of the noninstitutionalized US civilian population, ages > or = 4 years, which included non-Hispanic whites, non-Hispanic blacks, and Mexican-Americans. Apo B concentrations were the same in males and females, lower in black males than in other males, low in childhood (approximately 0.80 g/L) and increasing to approximately 1.2 g/L in adults, and higher in younger women on hormones. Apo AI was higher in females than males, higher in blacks than in others, remained constant from childhood to adulthood (approximately 1.35 g/L) in males, but increased with age (approximately 1.30 g/L to approximately 1.55 g/L) in females, and was higher in women taking hormones. These are the first national probability estimates of apo B and apo AI in the US and are referable to the WHO-IFCC First International Reference Materials for apo AI and B.

Biological variation of lipids and lipoproteins in fingerstick blood.

The biological variability of total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), and calculated low-density lipoprotein cholesterol (LDL-C) was determined in three serial (monthly) capillary and venous specimens from 83 subjects. The analytes were quantified with a desktop analyzer. We saw no differences in the coefficient of biological variability (CVb) between capillary and venous specimens for any analyte (TC, 5.2%; TG, 14.7%; HDL-C, 7.2%; LDL-C, 5.4%). The average analytical variability (CVa) for each analyte, determined in quality-control pools, was; TC, 5.0%; TG, 5.2%; HDL-C, 5.8%; and LDL-C, 7.5%. Compared with standardized laboratory measurements, the desktop analyzer exhibited a significant (P < 0.001) positive bias for all analytes (average bias: TC, 5%; TG, 16%; HDL-C, 6%; and LDL-C, 2.4%). Thus, the biological variation of lipids and lipoproteins was the same in fingerstick and venous samples, and the desktop analyzer showed inherently greater analytical variability.

Measurement of apolipoproteins A-I and B during the National Health and Nutrition Examination Survey (NHANES) III.

We measured apolipoproteins (apo) A-I and B by rate immunonephelometry (rate INA) during Phase 1 of the National Health and Nutrition Examination Survey (NHANES) III. We also made the measurements by radial immunodiffusion (RID) in a 20% subset of the samples. Aliquots of this subset were also analyzed in the Northwest Lipid Research Laboratories by fixed-time INA calibrated to the World Health Organization (WHO)-International Federation of Clinical Chemistry (IFCC) First International Reference Materials for Apolipoproteins A-I and B. The CVs for the rate INA and RID measurements were: apoA-I, 4.5-7.7% and 2.5-7.6%, respectively; apoB, 2.3-5.3% and 2.3-6.4%, respectively. In NHANES III, rate INA values (x) can be transformed to WHO-IFCC Reference Material-based values (y) as follows: for apoA-I, y = 0.87x + 251.8 mg/L (r = 0.93, SEslope = 0.13, SEintercept = 17, n = 708); for apoB (mg/L), y = 1.068x + 112.8 mg/L (r = 0.98, SEslope = 0.08, SEintercept = 7, n = 646).