Zinc kinetics in preterm infants: a compartmental model based on
stable isotope data.
Wastney, M. E., Angelus, P., Barnes, R. M. and Siva Subramanian, K. N.
Department of Pediatrics, Georgetown University Medical Center,
3800 Reservoir Rd., N.W., Washington, D.C. 20007, Department of
Chemistry, University of Massachusetts, Box 34510, Amherst, MA 01003
-4510
APStracts 3:0232R, 1996.
Zinc is an essential nutrient for growth however little is known about
zinc kinetics (absorption, distribution and excretion) in preterm
infants (<38 wk gestation). Zinc kinetics were studied in two
preterm infants (gestational ages 32 and 33 wk) following oral or
i.v. administration of a stable isotope (70Zn). Plasma, red blood
cells (RBC), urine and feces were sampled for up to 30 d. Isotope
enrichment was measured in tissues by inductively coupled plasma
(ICP)-mass spectrometry and zinc was determined by ICP-atomic
emission spectrometry. Data were analyzed by compartmental analysis
using SAAM31. Zinc intake increased during the studies and, because
body zinc was not in steady state, both tracer (70Zn) and tracee (Zn)
data were fitted using analogous models. A model for adults (Am. J.
Physiol. 251:R398-R408,1986) was modified to fit data from the
preterm infants. RBC data were fitted using one compartment (vs. two
in adults) and an adult RBC subsystem was included in the model to
account for zinc introduced during blood transfusions. Exchange of
zinc between compartments that were not sampled was based on zinc
distribution in neonates. Absorption was 42% and 34% and endogenous
fecal excretion, based on i.v. data, was 15 [mu]g/kg/d. The model can
be used to quantify changes in zinc kinetics of preterm infants with
age, weight and zinc intake for evaluating nutritional requirements
with growth.
Received 11 January 1996; accepted in final form 31 May 1996.
APS Manuscript Number R12-6.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 28 June 96