Enteral Feeding for Moderately Premature and Low Birth Weight Infants: A Single-Center Retrospective Observational Cohort Study

Controversy exists in clinical practice regarding optimal initial enteral feeding (EF) for moderately premature and low birth weight (BW) infants. We included 96 infants stratified into 3 groups (I: 1600-1799 g [n = 22]; II: 1800-1999 g [n = 42]; III: 2000-2200 g [n = 32]). The protocol recommended starting with minimal EF (MEF) in infants weighing <1800 g. On the first day of life, 5% of the infants in group I did not follow the protocol mandating MEF, but started with exclusive EF instead, compared to 36% and 44% of the infants in groups II and III, respectively. The median number of days until exclusive EF was achieved was 5 days longer for infants receiving MEF than for infants who had received normal portions of EF from birth onward. We observed no significant differences in feeding-related complications. We advocate omitting MEF in moderately premature infants with a BW of 1600 g or higher.

Endogenous Oxalate Production in Primary Hyperoxaluria Type 1 Patients

BACKGROUND

Primary hyperoxaluria type 1 (PH1) is an inborn error of glyoxylate metabolism, characterized by increased endogenous oxalate production. The metabolic pathways underlying oxalate synthesis have not been fully elucidated, and upcoming therapies require more reliable outcome parameters than the currently used plasma oxalate levels and urinary oxalate excretion rates. We therefore developed a stable isotope infusion protocol to assess endogenous oxalate synthesis rate and the contribution of glycolate to both oxalate and glycine synthesis in vivo .

METHODS

Eight healthy volunteers and eight patients with PH1 (stratified by pyridoxine responsiveness) underwent a combined primed continuous infusion of intravenous [1- 13 C]glycolate, [U- 13 C 2 ]oxalate, and, in a subgroup, [D 5 ]glycine. Isotopic enrichment of 13 C-labeled oxalate and glycolate were measured using a new gas chromatography-tandem mass spectrometry (GC-MS/MS) method. Stable isotope dilution and incorporation calculations quantified rates of appearance and synthetic rates, respectively.

RESULTS

Total daily oxalate rates of appearance (mean [SD]) were 2.71 (0.54), 1.46 (0.23), and 0.79 (0.15) mmol/d in patients who were pyridoxine unresponsive, patients who were pyridoxine responsive, and controls, respectively ( P =0.002). Mean (SD) contribution of glycolate to oxalate production was 47.3% (12.8) in patients and 1.3% (0.7) in controls. Using the incorporation of [1- 13 C]glycolate tracer in glycine revealed significant conversion of glycolate into glycine in pyridoxine responsive, but not in patients with PH1 who were pyridoxine unresponsive.

CONCLUSIONS

This stable isotope infusion protocol could evaluate efficacy of new therapies, investigate pyridoxine responsiveness, and serve as a tool to further explore glyoxylate metabolism in humans.