Reference Intervals of Apolipoprotein E in Healthy Chinese Han Adults

Background: Reference intervals (RIs) of Apo E levels are an important parameter for the clinical evaluation of patient health, and the RIs of serum Apo E could be variable in different population. We plan to establish RIs of apolipoprotein E (Apo E) according to the CLSI EP28-A3 guideline in healthy Chinese Han adults. Methods: Serum Apo E values of 1,206 healthy adults (from 19 to 87 years old) were measured by immunoturbidimetry. The relationship between Apo E and age was analyzed by using Spearman's correlation. The differences between the gender and age groups were compared using Mann-Whitney U test/Kruskal-Wallis H test. We calculated recommended nonparametric Q(2.5) and Q(97.5) percentile intervals and the 90% confidence intervals (CI) of lower and upper limits to define the age- and gender-related RIs. Results: The level of Apo E was higher in females than males. Apo E was significantly associated with aging in adult females (r = 0.108, p < 0.05), but not in males (p = 0.518). The RIs of Apo E for females were 0.0268 - 0.0619, 0.0247 - 0.0603, and 0.0269 - 0.0658 g/L for 18 - 29, 30 - 59, and >= 60 years old, respectively, that for males was 0.0242 - 0.0579 g/L. Conclusions: Our results established the age- and gender-specific RIs of serum Apo E in healthy Chinese Han adults in our laboratory.