Serum lipid levels in infants and mothers at parturition

258

CLINICA

SERUM

LIPID

:\. KAI’L:\N

LEVELS

AND VIVIEN

IN INFANTS

ACTA

AT PARTURITION*

F. LEE

Department of b’iochemistr~~, Uxivevsity (Received

AND MOTHERS

CIIIMICA

ofWashington,

Seattle,

LVash. (1U.S.A .)

September rgth, 1964)

SUMMARY

The concentrations

in umbilical

cord serum and maternal

triglycerides, cholesterol and lipid phosphorus American newborns and their mothers. Maternal of parturition while those of the infants are far glyceride levels in the newborns are 20% of the

venous

serum

of

were established for a group of 56 lipid levels are elevated at the time below the mothers’ values. The trimaternal concentration while those

for cholesterol and lipid P are 40% as high. All lipid concentrations increased appreciably in the infants by the third day of life, with the greatest relative rise occurring in the glyceride fraction. The serum triglyceride concentration in the American newborns was identical with that of a Swedish group despite the fact that the other lipid components were higher in the former population. A comparison of the serum cholesterol concentration of newborns in various countries revealed that it generally is highest in America.

Some fifty years ago, when lipid methods were still very crude, Herrmann and Neumann1 reported that the serum cholesterol concentration of human infants at birth was much lower than that of their mothers. Since that time, this has been conreports. In some of firmed many times in many lands 2 1’ despite a few contradictory the studies, lipid phosphorus was also determined but there are very little data concerning the concentration of triglycerides. No methods for the direct measurement of serum triglycerides were available until recently, and indirect measurements are subject to considerable error because the calculations are based upon several assumptions concerning fatty acid composition of the lipids as well as the measurement of 4 separate constituents, namely, total fatty acids, total cholesterol, free cholesterol and lipid phosphorus. Two years ago, Brody and Carlson 16 determined the serum lipid levels of 52 Swedish newborn infants and employed a triglyceride method that measured the glycerol of glycerides after removal of phospholipids. The present study was undertaken in order to determine the serum concentra* Presented at the National meeting of the hmcrican Mass., _-2ug. 20, 1964. This investigation was supported in part by a United 8423-01.

Clin. Chim. Acta, IZ (1965) 255-263

Association States

Public

of Clinical Health

Chemists,

Scrvicc

Grant

Boston, ii

HE

SERUM

LIPID IN INFANTS

tions of triglycerides

AND MOTHERS

(measured directly),

259 cholesterol

and lipid phosphorus

in American

newborns and to compare them with the Swedish values. This is the first phase of a study designed to establish normal values of serum lipid constituents in children of various ages. Because of a possible relation to coronary disease or atherosclerosis, the serum lipid concentration in adults has been studied much more intensively than in children. IviATEKlALS _%ND METHODS

Maternal and umbilical cord blood was taken from 56 unselected pregnancy cases at University Hospital, University of Washington, at the time of delivery. The blood was permitted to clot, the serum separated by centrifugation and stored at -20” until analyzed. Three days later, a sample of blood was taken from the infants by heel puncture and from the antecubital vein of the mothers.

a. ~~~~~~~~Y~~~s. Triglycerides

were directly

measured

by the Kaplan

and Lee’”

modification of the method of Van Handel and Zilversmit I** 20. The method was scaled down so that duplicate determinations could be performed on 0.1 ml of serum. Phospholipids were adsorbed on Zeolite* as the remaining lipids were extracted into chloroform. After saponification, each mole of glycerol derived from glycerides was converted into 2 moles of formaldehyde by periodate oxidation and measured spectrophotometrically after treatment with chromotropic acid. h. C~~Les~ey~Z.An 80-,ul portion of serum was extracted with a chloroformmethanol mixture (a : I) and made up to 2.0 ml volume. o.5-ml portions were taken for the estimation of total cholesterol by the fluorometric** method of McDougal and Farmcr2*. c. Lipill P. An aliquot of the chloroform--methanol extract was taken for the determination of lipid P. After evaporation of the solvent, the lipid residue was digested with perchloric acid at 185” as described by Zilversmit and Davisz2. After cooling, the phosphate was converted into a stable phosphomolybdate complex by heating in a boiling water bath in the presence of aminonaphtholsulfonic acid and ammonium molybdate a3. The color intensity was measured in a Beckman DU spectrophotometer at 820 rnp. RESULTS

The mean values and standard deviations of the serum infant and maternal lipids at parturition are shown in Table I. For ease of comparison with other data in the literature, triglyceride concentration is reported both as mmoles/l and as mg/roo ml; the tatter was obtained by multiplying the mmoles/l x 885/10. The mean concentrations of triglycerides, cholesterol and lipid P were 0.38 mmole/l (34 mg/roo ml), g5 mg/roo ml and 5.3 mg/Ioo ml, respectively, for the newborns. There was no sex difference in lipid distribution. The respective maternal levels were much higher.

* IV. A. Taylor Co. 7po York Rd., Baltimore, Md. ** Model No. III Turner Fluorometer, G. EC. Turner .Associatrs, z5.q Pulgas Ave., Palo hlto, Calif., 94303. CZirz.CAim. Acta, 12 (1965) 258-263

260

A. KAPLAN,

V. F. LEE

being 1.80 mmoles/l (159 mg/Ioo ml) for triglycerides, 264 mg/Ioo ml for cholesterol and 12.9 mg/Ioo ml for lipid P. Thus the newborn triglyceride Concentration is only 20% as high as that of the mother while the cholesterol and lipid P values are about 407;~ of maternal values. If one takes into consideration the elevation in serum lipid TXBLE I MEANCONCENTRATION OFSERUMLIPIDS.4TBIRTH Ilzfant

Constituc?zf

mglIo0 Triglycerides Cholesterol

Lipid 1’

f’hospholipids*

*

ml

34 95 53

’ 4” 18

‘33

25

mm&/l

mm&~1

0.38 ~0.16

1.80 L0.61

I.0

* Mean ,standard deviation. * * Calculated as lipid P x 15.

Cholesterol

mg /lOOmI

Fig. I. Distribution diagram of the umbilical cord swum of 56 infants.

concentrations

!!b LcidP

3.0 5.0 10 90 mg/lOOml of triglycerides,

cholesterol

ant1 lipid

I’ in the

concentration that occurs in pregnancy, the lipid levels in the newborns are still much below those of normal adults who have mean concentrations of 1.0 mmole/l, 194 mg/ for triglycerides, cholesterol and lipid P IOO ml and 9.2 mg/roo ml, respectively, (ref. 24). The distribution frequencies of the serum concentrations of triglycerides, cholesterol and lipid P in umbilical cord serum are shown in Fig. I. All lipid fractions exhibit an asymmetry in their distribution. There are more cases with values below the mean concentration than above it. The cholesterol distribution is fairly symmetrical for 3/4 of the diagram. Nine infants with high cholesterol concentrations (above IZO mg/Ioo ml) were responsible for a skew distribution. Lipid values were determined in both mothers and infants 3 days following parturition and these results are summarized in Fig. z. A great increase in triglyceride concentration occurred in the infants, rising almost threefold within 3 days; the initial concentration of 0.38 mmole/l (34 mg/Ioo ml) rose to 1.04 mmoles/l (92 mg/Ioo ml) after z to 3 days of life. The increase in triglyceride concentration was far greater than for either cholesterol or lipid P which rose approximately 40% in the same time period. Thus, by the third day of life, the concentration of serum triglycerides in the infants approximated those of adults (non-pregnant) while cholesterol and lipid P levels were Clin. Chim. Acta,

IL (1965)

258-263

SERUM LIPID IN INFANTS

still significantly

261

AND MOTHERS

below the general

adult average.

Many workers had observed

that

serum cholesterol 4~*~8 levels rise in the early days of life but this is the first report concerning the triglycerides, In marked contrast to the infant, all lipid constituents decreased

slightly

in the mothers’

serum during this interval.

mg/lOOml 250

Triglycerides

Fig. 2. Comparison three days later.

Cholesterol

of the serum

lipid

mg!

LIpId PxlO

concentrations

aAmerican

of infants

ant1 mothers

at parturition

antI

infants (this Study)

!-J3f6edish cnfantsBrcdy BCarlsoi-9

qfSwedish in~nts(~fst~t)

Triglycf@eschoiesterol

Llpld

PxlO

choksteroi .&m Phospholipid

I;&. 3. Comparison of the serum lipid concentrations with those in Sweden (Brody and Carlson; Rafstedt).

of newborn

infants

in .\merica

(this study)

DISCUSSION

This study confirms the finding of Brody and Carlson l6 that the concentration of serum triglycerides is quite low in the newborn. Employing a method similar to theirs for the estimation of this constituent, it was found that its level in Seattle infants was identical with those from Stockholm (0.38 mmole/l) despite large differences in cholesterol concentration; this is demonstrated in Fig. 3. The cholesterol level of Seattle infants was 95 mg/roo ml compared to 66 and 67 mg/roo ml respectively in the 2 Swedish studieslas9. The lipid P concentrations, in mg/roo ml, were 5.3 in Seattle compared to 4.2 and 4.8 in Sweden. The cholesterol: phospholipid ratio, of course, was higher in the Seattle group. This study also demonstrates that the concentration of triglycerides is relatively Clin. Chinz. Acta,

IZ (1965) 258-263

262

A. KAPLAN, V. I;. LEE

much lower in umbilical cord serum, compared to that of maternal serum, than either cholesterol or lipid phosphorus. Thus, the concentration of triglycerides in American newborns from the Seattle area is only ZIP; of that of the mothers while that of cholesterol and lipid P are 36 and +9/o respectively, of their values.

~.

_.-_-

This study 5 0 L0 ‘4 10

l!.S..\

jb 10 7 10 50

273

52

4.2

4.8

3

32 11

4

30

‘>

‘5 x ‘i 13 Lf

110 1q** rrl) 217 44tt 51: 37::

-

3.8

10.7*

-

SWdWl

--

‘2-3

9.7 ._

Germanv Czechoslovakia 1sra.el Guatemala South

Africa

_.

* This lipid phosphorus value does not agree with any other reported results. ** TIVO infants and their mothers were excluded from this study because one mother was a frank diabetic, and the other had an unexplained h~percholesteroIcmia (exceeding -150 m&too ml). + lrpper income groups, ii Low income groups. : Of .-\frican nationality. : $ Of European nationality.

In Table II, the results of many important studies concerning the concentration of serum lipids in the newborn are summarized and grouped according to countries in which the investigations took place. In half of the reports, lipid P was not measured; cholesterol measurements are the most numerous while direct triglyceride analysis was confined to two studies. With the exception of one report from Israel” on a.small number of infants, cholesterol levels in American newborns are higher than in those from all other countries. If Sperry’s small series of 7 infants is excludede, the remaining American studies on 132 infants report an average cholesterol value of 8s mg/roo ml compared to values below 70 mg/roo ml for most of the other countries. The cholesterol values reported in this study exceed the other American values by 6 to zoy(,. The chnlesterot concentration of the American women at term is not much higher than in the women of other countries except Czechoslovakia I5 and the African women of South Africa”. The cholesterol levels of the European women in South Africa, however, are indistinguishable from those in other countriesll. There has been considerable interest in population differences in serum lipid levels, particularly with respect to cholesterol, and the general opinion has been that long term dietary habits probably account for these differences. Within a population

SEllUM

LIPID

IN

INFANTS

.iND

253

MOTKEiiS

group, a higher economic level usually is associated with a greater ~(~nsunlpti(~n of animal fat and the higher serum cholesterol concentration has been ascribed to this. Thus, in the study from Guatemala*“, the pregnant mothers from the low income group had a somewhat lower serum cholesterol than those in the upper income group. This difference is reflected more markedly in the South African study I1 where the African mothers had a much lower serum cholesterol than the European mothers residing there. Despite these differences in maternal cholesterol concentration, the umbilical cord serum cholesterol was the same in each so~jo-econ~)mi~ group (Table II) It was interesting

to compare

the lipid levels of American

infants

at birth with

those of Sweden (Fig. 3). Despite the presence of a much higher concentration cholesterol in Seattle children’s serum, the triglyceride concentration was identical

of in

the Seattle and Stockholm studies. The Seattle children had a somewhat higher lipid P concentration and cholesterol: phospholipid ratio. Helmy and Hack25 have further delineated the differences in plasma phospholipids between mothers and newborns. They have shown that the latter’s plasma phosphatidyl et.hanolamill~ is very greatly reduced in concentration, compared to maternal plasma, while phosphatidyl choline is only moderately decreased. Differences in concentration of maternal and fetal lipids have been ascribed to failure of lipids to pass the placental barrier.VC’hile this certainlyisafactor,differences between fetal and adult metabolism must also play a part. Van Duyne and Have1 26 ascribe the rapid, postnatal rise in lipid concentration to a shift from a primary utilization of carbohydrates for energy purposes to the utilization of fat. Perhaps the quiescent state of fat utilization in the fetus and the absence of a need for fat mobilization is responsible for the low serum triglyceride concentration at birth. KEl+X?HENCES I

2 3 4 5 6 7

S 9 10

1I

AND J, NEUMAKN, Bzochem. il., 43 (1~12) 47. SLEMONS AND H. J. STANDER, Bull. Johm Hopkins Hosp., 34 (1923) 7. I”. GY~RGY, Klin. Wochschu., 3 (1924) 483. R. HORNUNG, Deut. Med. Wochschu., 52 (1926) 1849. M. B. GORDON ANI)D.J.COHN, Am. J. Dzseases ChiEdvew, 35 (rgz8) 193. CV. N. SPERRY, -4~. f. f.keasesC~z~ld~e~, 51 (1936) 84. E. NI. BOYD, .4m. .J. Diseases Children, 52 (1936) 1319. A. SADOWSKY, A. BRZEZINSKI, Y. M. BROMBERG ASD F. ROSENTHAL, ExPIE. Med. .i;uq.,j (r947) 259. S. RAFSTEDT, .4&a Paediot.. 44, Suppl. No. IOZ (1355). E. SOHAR, E. T. BOSSAK, C. 1. WANG AND D. ADLERSBER~~, Science,~rj (195b) 4br. I. BERSOHN AND S. W'RYBURNE, A4m. /. Clin. N&r., 4 (1956) 117. B. JOSEPHSON AND C. GYLLENSWARD, Stand. J. Clix. Lab. Invest., 9 (1957) 29. J. M~NDEZ, B. S. SAVITS, M. FLORES AND N. S. SCRIMSHAW, Am. J. Clin. ~Vutv., 7 (1959) 595. E.

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22 23 24 25

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hND

v.

*i-ISCHLER,

Zenfr.

+wzeco~.,

8-j (196r)

902.

S.

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258-263