Low and High Density Lipoprotein Cholesterol Interrelationships in Neonates with Low Density Lipoprotein Cholesterol ≤ the 10th Percentile and in Neonates with High Density Lipoprotein Cholesterol ≥ the 90th Percentile

Summary: Since the inverse relationship between high density lipoprotein cholesterol (C-HDL) and low density lipoprotein cholesterol (C-LDL) is generally recognized in school children and in adults, but not at birth, the current study was focused on neonates having C-HDL ≥ the 90th percentile and neonates with C-LDL ≤ the 10th percentile to determine whether any distinctive relationships existed at the extreme limits of the frequency distribution among C-HDL, C-LDL, and total plasma cholesterol. Sixty-three neonates with C-LDL ≤ the 10th percentile (20 mg/dl), and 58 with C-HDL the 90th percentile (50 mg/dl) were selected in the consecutive order of their birth as part of an ongoing cord blood lipid and lipoprotein survey. Comparisons of the hypobeta- and hyperalphalipoproteinemic neonates with 117 previously described unselected neonates were made. In the 117 unselected neonate controls, both C-HDL and C-LDL levels were closely correlated with total cord blood cholesterol (r = 0.63, 0.76, P < 0.01), whereas C-HDL was not significantly related to C-LDL (r = 0.002). In the 63 hypobetalipoproteinemic neonates, C-HDL correlated closely with total plasma cholesterol concentrations (r = 0.98, P < 0.01). C-LDL failed to correlate with total plasma cholesterol (r = 0.07). In the face of low cord blood C-LDL, nearly all of the total plasma cholesterol variation was accounted for by C-HDL. C-HDL was not significantly related to C-LDL (r = −0.15). In 58 hyperalphalipoproteinemic neonates, C-HDL did not significantly correlate with total cholesterol concentrations (r = 0.22), whereas C-LDL was closely related (r = 0.88, P < 0.01), with nearly all of the total plasma cholesterol variation accounted for by C-LDL. The inverse C-HDL to C-LDL relationship was not significant (r = −0.18)Speculation: Whatever factors contribute to both the overall and to the extremes of the C-HDL and C-LDL frequency distributions at birth, C-HDL and C-LDL in neonates appear to be under independent metabolic control.