In a prospective, controlled study, plasma and urinary taurine concentrations were determined weekly, between postnatal weeks 3 and 18, in (1) seven sick infants (gestational age <28 weeks, birth weight ≤1000 gm) who received a taurine-free total parenteral nutrition solution for 32 to 49 days (group P) and who subsequently were formula fed and (2) eight sick infants matched by gestational age and birth weight, who received formula or human milk from day 3 to 4 of life (group E). Ten healthy full-term infants ranging in age from 1 to 18 weeks and fed with formula provided normal values (group C). Significantly lower mean plasma taurine values (range 1.59 to 3.43 μmol/dl) were found between postnatal weeks 3 and 7 in group P compared with group E (range 5.54 to 6.97 μmol/dl) and with group C (5.6±0.34 μmol/dl). After initiation of feeding, plasma taurine concentrations in group P increased to normal. Markedly elevated values of mean fractional excretion of taurine, 38% to 56%, were found between weeks 3 and 5 in groups P and E compared with group C (15.5±3.2%). In contrast, during the same period, low urinary taurine values (4.9% to 6.7%) were found in two larger, older infants receiving total parenteral nutrition whose plasma taurine values were in the normal range. After week 5, urinary taurine values were in the control range in all groups. We conclude that the absence of taurine in total parenteral nutrition solutions administered to very low birth weight infants and the limited ability of the immature kidney to adapt to low taurine intake by "upregulation" of tubular taurine reabsorption may result in depleted taurine body pools during the first weeks of life. This inability to conserve taurine by the immature nephron could potentially have a deleterious effect on the developing brain and retina in these infants, and indicates a possible need for taurine supplementation.
Bibliographical noteFunding Information:
Taurine.is a B-amino acid with vital biologic functions, including neuromodulation, cell membrane stabilization, an- Supported in part by National Institutes of Health grants P30AM35747 and DK-37223,. Submitted for publication June 23, 1989; accepted Sept. 7, 1989. Reprint requests: Israel Zelikovic, MD, Department of Pediatrics RD-20, University of Washington, Seattle, WA 98195. 9/23/16630 tioxidation, detoxification, bile acid conjugation, and osmoregulation, l Taurine is considered essential for the normal development of the brain and the retina. 2 Depletion of this amino acid during early life results in degeneration of retinal photoreceptors, central nervous system abnormalities, and growth depression in young animals, 1 as well as in abnormal electroretinograms in children 3 and auditory brain-stem evoked responses in premature infants. 4