Serum Lipoprotein(a) Levels in Japanese Children with Normal Low-density Lipoprotein Cholesterol

To determine the serum lipoprotein(a) (Lp(a)) levels in Japanese children with normal low-density lipoprotein cholesterol (LDL-C) levels.

Data from 170 pediatric outpatients aged 0-17 years who underwent Lp(a) measurements were included. Among them, 146 children (64 boys) with LDL-C levels ＜140 mg/dL were analyzed. At the time of blood sampling, none of the participants had any physical symptoms, and routine laboratory examinations showed no abnormalities. The association between the Lp(a) levels and clinical parameters was evaluated.

The mean age of the children was 9.0 years, and 25 were obese. The serum Lp(a) concentrations ranged from 1 to 82.3 mg/dL and showed a right-skewed distribution. The median Lp(a) levels were 8.0 mg/dL (27.6 nmol/L), 7.5 mg/dL in boys, and 8.4 mg/dL in girls. The 95th percentile was 29.7 mg/dL (109.6 nmol/L). Lp(a) levels were not significantly correlated with age, overweight indices, thyroid hormones, or C-reactive protein. Among the lipid-related parameters, weak positive correlations were observed for total cholesterol and apolipoprotein B. Elevated Lp(a) levels were more prevalent in children with elevated LDL-C levels. However, among children with LDL-C ＜140 mg/dL, no statistically significant association was observed between LDL-C and Lp(a), and this association was further attenuated when LDL-C corrected for the contribution of Lp(a) was used. Similar findings were observed in the multivariable regression analyses.

In children with LDL-C ＜140 mg/dL, the Lp(a) levels appear to be largely regulated independent of body size and LDL-C. The median Lp(a) was 8 mg/dL (≈30 nmol/L), and levels ≥ 30 mg/dL (≈110 nmol/L) were considered to be high.