Reference distributions for apolipoproteins AI and B and the apolipoprotein B/AI ratios: a practical and clinically relevant approach in a large cohort

Abstract

The two serum apolipoproteins in the highest concentrations, apolipoprotein (apo) AI and apolipoprotein B, and the apolipoprotein B/AI ratio are measured to assess clinical risk for atherosclerotic heart and peripheral vascular diseases. The study is based on a cohort of over 37,000 Caucasian individuals from northern New England measured in one laboratory by immunonephelometry using standardized reference materials. All samples received for protein analyses were accepted provided adequate identifying information was available. Laboratory and demographic information was entered into a single database for subsequent study. Our results show that for males without evidence of inflammation, values of apo AI change little through life. For females, however, values gradually increase until about 60 years of age then fall somewhat thereafter. Among adults, females have higher apo AI values on average, than males. Apo B values change significantly through life, increasing after the end of the second decade to a peak during the sixth decade, then falling thereafter. In the past, concern has been expressed that apo AI is an acute phase reactant (APR), thus complicating cardiovascular risk assessment. The effects of an APR (C-reactive protein >or=10 mg/L) on apo AI, but not on apo B, are measurable for both sexes, most noticeably beyond the age of 60 years in males and females. When values were expressed as age- and gender-specific multiples of the median (MoMs), the resulting distributions fit a log-Gaussian distribution well over a broad range. The size of the relatively homogenous cohort, by a standardized approach, provides a firm basis for comparison to preexisting reference intervals and for establishing a clinically useful and current reference interval for the three main apolipoprotein values.

Reference distributions for apolipoproteins AI and B and B/AI ratios: comparison of a large cohort to the world's literature

“…This is the seventh in a series of meta-analyses for serum protein reference intervals. Our practical approach applied to published population data produces many reference intervals comparable to our companion study (98), which reported reference data for apo AI, apo B, and the B/AI ratio based on over 27,000 observations. Continued.…”

“…If a published observation was based on less than 10 observations, it was combined with an adjacent age group from the same publication, if possible, otherwise it was not shown. For purposes of comparison, the solid and dashed lines represent the median levels found for males and females, respectively, in our companion study (98). Figure 1A shows the reported apo AI median values from the 64 published studies considered acceptable.…”

“…The three symbol sizes represent the number of observations in each group (small, medium, and large circles, representing over 100, 50 to 99, and 10 to 49 observations, respectively). The solid (male) and dashed (female) lines are the regressed median levels from our large cohort study (98). papers or those that only examined patients with specific diseases were excluded.…”

Usefulness of MALDI-TOF/MS Identification of Low-MW Fragments in Sera for the Differential Diagnosis of Pancreatic Cancer

“…The mean Apo-A1 levels were significantly reduced in PaCa with respect to HC, patients with ChrPa, DM, and CG and in patients with GC with respect to HC and CG (1-way ANOVA: F = 10.49, P G 0.0001). Because Apo-A1 reference values are dependent on age and sex, Apo-A1 above the 2.5 percentile of the reference values for age and sex were classified as normal, 27 whereas values below this cutoff were classified as low. Low Apo-A1 levels were most frequently found in PaCa (43.2%) and GC (31.3%) cases than in HC (0%), ChrPa (23.1%), CG (0%), and DM (9.8%) (W 2 = 39.87, P G 0.0001).…”

Apo-B/AI ratio identifies cardiovascular risk in childhood:The Australian Aboriginal Birth Cohort study

“…The reference population for the Apo-B/A1 ratio was derived from a large US cohort that included significant numbers within the paediatric age group. 13 A single group mean was used for each element of the lipid profile, as the variation between gender and age groups is minimal with the exception of Apo-A1 and the Apo-B/A1 ratio. 11 Gender-specific means are presented for Apo-A1 and Apo-B/A1 ratio.…”