Distribution of Lipoprotein(a) Levels Among Children with Elevated Low-Density Lipoprotein Cholesterol Identified Through Universal Pediatric Lipid Screening.

Children with elevated low-density lipoprotein cholesterol (LDL-C) levels, suspected familial hypercholesterolemia (FH), and elevated lipoprotein(a) (Lp(a)) levels are considered to have a particularly high lifetime risk of atherosclerotic cardiovascular disease. Nevertheless, the distribution of Lp(a) levels among children with elevated LDL-C levels remains unclear. This study aimed to clarify the distribution of Lp(a) levels and their association with pathogenic FH variants in children with elevated LDL-C levels. A total of 97 children with LDL-C levels ≥ 140 mg/dL suspected of having FH who underwent genetic testing at Kagawa University Hospital between January 2018 and May 2025 were analyzed. Lp(a) levels were measured using the Lp(a) Latex "DAIICHI" assay and converted from mass units (mg/dL) to molar units (nmol/L) using the calibration-based conversion formula. Clinical and lipid parameters were compared according to Lp(a) levels (≥ 105 vs. ＜105 nmol/L) and the presence of pathogenic FH variants. Lp(a) levels exhibited a right-skewed distribution, with a median of 57.6 nmol/L (15.9 mg/dL) and an interquartile range of 24.0-93.4 nmol/L (7.0-25.4 mg/dL), and 21.6% of children had levels ≥ 105 nmol/L. Pathogenic FH variants were identified in 44 children. No significant differences were observed in either clinical or lipid parameters according to Lp(a) levels (≥ 105 vs. ＜105 nmol/L) or the presence of pathogenic FH variants (P = 0.672). Regardless of the presence of pathogenic FH variants, approximately 20% of the children had Lp(a) levels ≥ 105 nmol/L. These findings emphasize the importance of early lipid management and suggest that Lp(a) measurement may contribute to future cardiovascular risk stratification.