Reference intervals of Apo A-1 , Apo B and Apo B/Apo A-1 ratio in sample of macedonian population

Abstract

The disorders of serum concentration of Apolipoproteins A-1 and B (Apo A-1 and Apo B), as well as of Apolipoprotein B/Apoliporotein A-1 ratio (Apo B/ Apo A-1) are considered to be independent risk factors for coronary heart disease. It is recommended that each laboratory should asign its own reference intervals for Apo A-1 and Apo B, as well as for Apo B/Apo A-1 ratio, as these depend on the geographical location. For this purpose we determined the serum concentration of Apo A-1 and Apo B and we calculated the Apo B/Apo A-1 ratio in 122 healthy individuals from Macedonian population (70 women and 52 men), aged 18-60 years. We used commercial, standardized manual immunoturbidimetric assay (Randox). The obtained concentrations (x ± SD) were: Apo A-1 = 1.39 ± 0.28 g/l in the female population and 1.42 ± 0.27 g/l in the male population, Apo B = 0.95 ± 0.24 g/l in the female and 1.00 ± 0.23 g/l in the male population. The calculated Apo B/Apo A-1 ratio was 0.70 ± 0.17 in the female subgroup and 0.72 ± 0.18 in the male subgroup. Student's t-test detected no significant difference (p>0.05) in mean values for Apolipoproteins A-1 and B and for Apo B/Apo A-1 ratio between female and male subgroups, which lead to the conclusion that division according to sex is not necessary from diagnostic point of view. The Apo A-1 and Apo B concentrations estimated for the mixed group (N=122) were 1.40 ± 0.28 g/l and 0.97 ± 0.23 g/l. The Apo B/Apo A-1 ratio estimated for whole group was 0.71 ± 0.17. The type of distribution of values for Apo A-1, Apo B and Apo B/A-1 ratio was tested by calculating the values of coefficient of asymetry (Skewness), coefficient of flatness (Kurtosis) and standard deviations of these coefficients. The distribution of values was according to Gaussian curve for all three parameters. Therefore, according to the normal distribution reference intervals for Apo A-1, Apo B and Apo B/Apo A-1 ratio was estimated parametrically (mean ± 2 standard deviations). Reference intervals for Apo A-1 were 0.84 - 1.96 g/l, 0.51 - 1.43 g/l for Apo B and 0.37- 1.05 for Apo B/Apo A-1 ratio.