Lipid profile and atherogenic indices soon after birth in Japanese preterm infants.

ABSTRACTAim: The intra-uterine environment affects the risk of development of cardiovasculardisease in adulthood. The aim of this study was to determine the influence of prematurityand foetal growth restriction on lipid metabolism, by assessing atherogenic indices soonafter birth in preterm infants. Methods: Blood samples were collected within 20 min of birth from 80 preterm infantswith a gestational age of ≤35 weeks. Serum total cholesterol (TC), low-density lipoproteincholesterol (LDLc), high-density lipoprotein cholesterol (HDLc), apolipoprotein-A1 (apoA1)and apolipoprotein-B (apoB) levels were measured. The ratio of TC/HDLc, LDLc/HDLcand apoB/apoA1 were also calculated. Correlations between these indices and gestationalage,birthweightandthestandarddeviation(SD)scoreforbirthweightwerealsodetermined. Results: Gestational age, birth weight and SD score for birth weight were negativelycorrelated with the TC/HDLc, LDLc/HDLc and apoB/apoA1 ratios. Conclusion: In preterm infants, prematurity and poor foetal growth may influence lipid andapolipoprotein metabolism and affect atherogenic indices at birth.INTRODUCTIONAdvances in neonatal intensive care in recent decades havebrought about dramatic improvement in the prognosis forpremature infants (1). However, as noted by Barker andOsmond in 1986 (2), evidence has accumulated that indicesof foetal growth, such as size at birth, are inverselyassociated with cardiovascular morbidity and mortality(3–5). The intra-uterine environment and early postnatallife are now generally accepted as important determinantsof the risk of cardiovascular disease in adulthood. Althoughthe exact mechanisms are unknown, it has been suggestedthat abnormalities in the metabolism of serum lipids mayexplain these associations (6). Lipid metabolism is a subjectof major importance in the nutrition of neonates becauselipids are the main structural components of cell mem-branes and therefore affect growth and development. In ahuman study (7), low birth weight (BW) was found to beassociated with higher total cholesterol (TC) concentrationsin adult men. However, a recent systematic review of theliterature on BW and blood cholesterol concluded thatthere was only a weak association between low BW andhigher TC (8).The lipoprotein profile in foetuses is quite different fromthat in adults because lipoprotein synthesis is low due toimmature hepatic function and the absence of intestinallipid absorption. The major plasma lipoprotein in foetuses ishigh-density lipoprotein (HDL), whereas in adults it is low-density lipoprotein (LDL) (9,10). Serum lipoprotein profilesin children are predictive of those in adulthood (11,12), andthere is evidence that this association with adult levels mayoriginate at birth (13,14). Several lipoprotein ratios or‘atherogenic indices’ have been defined in an attempt tooptimise the predictive capacity of the lipid profile. TC/HDL cholesterol (HDLc) and LDL cholesterol (LDLc)/HDLc ratios are risk indicators with a greater predictivevalue than isolated parameters used independently (15).The major apoprotein present in HDL is apolipoprotein-A1 (apoA1), which provides structural stability to thespherical molecule. In LDL, apolipoprotein-B (apoB) con-stitutes most of the protein content. The apoB/apoA1 ratiois therefore also of great value in detecting atherogenic riskand is often more useful than TC/HDLc and LDLc/HDLcratios (15).