Comparison of the Deuterium Dilution and Test-Weighing Techniques for the Determination of Human Milk Intake
The deuterium dilution and test-weighing techniques to determine human milk intake were compared in 5 exclusively breast-fed infants, mean age 93 days, and in 4 supplemented infants, mean age 112 days. Deuterium oxide was administered orally to the mothers at 100 mg/kg body weight. The monoexponential decay curve of 2H from the mother’s milk was defined from milk sampled on days 1, 2, 6, 10, 13, 14 of the experiment. Milk samples were defatted by centrifugation and the milk water was reduced to hydrogen gas for hydrogen isotope ratio measurements by gas-isotope ratio mass spectrometry (GIRMS). Total body water (TBW) of the infants was determined by dilution after the administration of 60 mg 18O/kg body weight. Infant urine was sampled on days 1, 2, 4, 6, 8, 10, 12, 14 of the experiment and analyzed for 2H and 18O enrichment by GIRMS. The SAAM27 computer program for compartmental analysis was used to estimate fractional rate constants and predict the average human milk intake over the 14 days of the experiment. The test-weighing procedure was conducted for 5 consecutive days. All supplemental formula and solid foods consumed during the 14 days were measured.