Human fetal albumin synthesis rates during different periods of gestation.
BACKGROUND
Despite nutritional intervention, albumin concentrations are often low in critically ill premature neonates.


OBJECTIVE
Our aim was to quantify albumin synthesis rates during early life under physiologic circumstances. Human fetuses thereby reflect the developmentally related optimal condition.


METHODS
Pregnant women undergoing elective cesarean delivery received 3 different labeled amino acid infusions starting at different times before surgery. With the use of mass spectrometry techniques, this novel model enabled us to quantify fetal albumin synthesis from a single blood sample taken from the umbilical cord after cesarean delivery. The fractional synthesis rate reflects the fraction of the albumin pool that is daily renewed. The absolute synthesis rate is the absolute amount of albumin that is daily synthesized. Results are expressed as medians (25th-75th percentile).


RESULTS
We studied 8 fetuses at 29.9 (28.4-35.4) weeks of gestation and 8 fetuses around term. Fractional synthesis rates in premature fetuses [17.5 (12.1-24.4) %/d] were higher (P = 0.02) than in mature fetuses [10.4 (9.1-13.7) %/d]. Absolute synthesis rates were also higher (P = 0.02) in premature than in mature fetuses: 280 (227-365) versus 205 (184-238) mg . kg(-1) . d(-1).


CONCLUSIONS
On a weight basis, albumin synthesis rates in premature fetuses were higher than in fetuses at term and were higher than the rates previously found in neonates after preterm birth. Considering that the premature fetal liver can synthesize albumin at a high rate, the observed hypoalbuminemia in premature infants therefore seems to suggest that current (nutritional) therapies fail to meet requirements necessary to sustain optimum albumin synthesis rates.
Department of Pediatrics, Division of Neonatology, Erasmus MC-Sophia Children's Hospital, Rotterdam, Netherlands.
Chris H P
CH
van den Akker
Henk
H
Schierbeek
Trinet
T
Rietveld
Andras
A
Vermes
Johannes J
JJ
Duvekot
Eric A P
EA
Steegers
Johannes B
JB
van Goudoever
D000328:Adult; D002247:Carbon Isotopes; D002585:Cesarean Section; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D005333:Fetus / Q000378:metabolism*; D005865:Gestational Age; D006801:Humans; D034141:Hypoalbuminemia / Q000209:etiology*; D007227:Infant Nutritional Physiological Phenomena; D007231:Infant, Newborn / Q000378:metabolism*; D007234:Infant, Premature / Q000378:metabolism; D008297:Male; D009587:Nitrogen Isotopes; D009751:Nutritional Requirements; D011247:Pregnancy; D012709:Serum Albumin / Q000096:biosynthesis*; D013997:Time Factors
D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D012709:Serum Albumin