Dual tracer stable isotopic assessment of calcium absorption and endogenous fecal excretion in low birth weight infants.
Using a dual tracer (44Ca orally and 46Ca i.v.) stable isotope technique, true dietary Ca absorption, endogenous fecal Ca excretion, and net Ca retention were measured in 12 low birth weight (1426 +/- 260 g) infants fed a high Ca-containing formula. Endogenous fecal Ca excretion averaged 7.2 +/- 4.1% of intake, and exceeded 10% of intake in three infants. Net Ca retention, 103 +/- 38 mg/kg/d, was consistent with previous studies of Ca retention obtained using mass balance techniques and correlated closely (r = 0.98, p less than 0.001) with true Ca absorption but not with endogenous fecal excretion (r = -0.40, p = 0.19). Although endogenous fecal excretion may represent a significant source of Ca loss for some low birth weight infants, these data suggest that net Ca retention in low birth weight infants fed a high Ca-containing formula is primarily determined by the total dietary Ca absorbed.
Abrams
S A
SA
Laboratory of Theoretical and Physical Biology, National Institute of Child Health and Human Development, Bethesda, Maryland 20892.
Esteban
N V
NV
Vieira
N E
NE
Yergey
A L
AL
D002127:Calcium Isotopes; D002136:Calcium, Dietary / Q000008:administration & dosage / Q000378:metabolism*; D005243:Feces / Q000737:chemistry; D006801:Humans; D007225:Infant Food; D007230:Infant, Low Birth Weight / Q000378:metabolism*; D007231:Infant, Newborn; D007408:Intestinal Absorption
D002127:Calcium Isotopes; D002136:Calcium, Dietary