Reference interval for the apolipoprotein B-48 concentration in healthy Japanese individuals

Small intestine-derived chylomicrons and chylomicron remnants, which are predominant in patients with postprandial hypertriglyceridemia, chylomicron syndrome and/or familial dyslipidemia, carry one molecule of apolipoprotein B-48(apo B-48) per lipoprotein particle. We investigated the reference interval for the apo B-48 concentration.

We studied 516 individuals who provided written informed consent and confirmed that they were not taking any medications. BMI, waist circumference, blood pressure and the fasting serum concentrations of LDL-C, triglyceride(TG), HDL-C and apo B-48 were measured. The Apo B-48 concentrations were compared according to sex, a pre- or postmenopausal status, dyslipidemia(LDL-C ≥140 mg/dL, TG ≥150 mg/dL, HDL-C ＜40 mg/dL), metabolic syndrome(MetS) and the number of risk factors.

The fasting apo B-48 concentrations(mean±SD) were significantly higher in men than in women(3.8±3.3 μg/mL vs 2.4±1.9 μg/mL, p＜0.001), subjects with a BMI of ≥25 kg/m(2) versus a BMI of ＜25 kg/m(2) (4.4±3.7 μg/mL vs 2.8±2.4 μg/mL, p＜0.001) and those with versus without MetS(6.5±4.3 μg/mL vs 3.0±2.6 μg/mL, p＜0.001). High apo B-48 concentrations were also observed in correlation with the number of risk factors for the MetS. The upper reference limit of apo B-48 was estimated to be 5.7 μg/mL among the 332 patients with normolipidemia, excluding those exhibiting a mean value above ±2.58 standard deviations(SDs), as the mean and range of mean ±1.96 SD were calculated to be 2.04 μg/mL(reference value) and 0.74 to 5.65 μg/mL(reference interval), respectively.

Based on our study of normolipidemic patients, the upper reference limit for the fasting apo B-48 concentration is estimated to be 5.7 μg/mL.