Cord-blood low-density lipoprotein cholesterol: estimation versus measurement with the preparative ultracentrifuge.

Abstract

C. J. GLUECK,’ P. STEINER, and V. LEUBA Cincinnati, 0th Ultracentrifugal quantitation of low-density lipoprotein (LDL) cholesterol in umbilical cord blood was compared with estimation of the concentration of low-density lipoprotein cholesterol. Comparison of LDL-u (ultracentrifuge determination] and LDL-e (estimated)’ gave a correlation coefficient of 0.934 in 39 neonates. Mean + S.D. LDL-u was 26.4 + 13, and LDL-e was 28 k 13 mg. per 100 ml. Determination of cord-blood cholesterol, triglyceride, and alpha lipoprotein cholesterol and estimation of LDL cholesterol by the formula LDL-e = plasma cholesterol-(Plasma alphalipoprotein cholesterol + plasma triglyceride divided by 5) provides an accurate estimation of cord-blood LDL. M easurement of cord-blood cholesterol and cord-blood low-density lipoprotein (LDL) cholesterol appears to offer promise in the early diagnosis of familial and neonatal Type II hyperlipoproteinemia.2-5 For neonates, children, and adults, determination of LDL cholesterol may provide for the most accurate diagnosis of familial and acquired Type II hyperlipoproteinemia (hyperbetalipoproteinemia) .l~ 4-6 Friedewald, Levy, and Fredrickson1 have reported a method for estimation of LDL which yields correlation coefficients of 0.98 and 0.99 when compared to LDL quantitated by ultracentrifuge in normal subjects and patients with Type II hyperlipoproteinemia. LDL cholesterol was estimated1 by Kwiterovich, Levy, and Fredrickson,5 in a small number of neonates who had 1 parent with documented Type II hyperlipoproteinemia, The correlation coefficient between LDL-u and LDL-e in these infants was 0.98.5 This methodology for estimation of LDL may be particularly applicable to cord-blood samples and measurement of LDL in infants, It obviates the need for large sample collection. Restrictions on its use (presence of chylomicrons, Type III hyperlipoproteinemia, and