ZINC AND COPPER EXCRETION AND ABSORPTION IN INFANTS WITH OSTOMIES

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We propose to examine the absorption and excretion of zinc and copper in infants with ostomies. This will be accomplished by measuring baseline excretion and serum levels of zinc, copper, and ceruloplasmin, and by utilizing stable isotopes of zinc and copper to measure absorption and excretion. When an infant with an ostomy is receiving primarily total parenteral nutrition (TPN) with minimal or no enteral feeds, we will collect ostomy output for 24 hours to measure zinc and copper excretion, and will measure serum zinc, copper, and ceruloplasmin levels. We will utilize stable isotopes of zinc and copper at two time points: when the infant still has the ostomy and is receiving primarily enteral nutrition without TPN, and lastly, when/if the patient s ostomy is removed with the bowels reanastamosed and the patient is stable on enteral feeds. For the first part of the study, excretion data for zinc will be obtained for ostomy patients. We hypothesize that infants with an ostomy will excrete more zinc in their stools than healthy term or preterm infants without ostomies. For the second part of the study, we will obtain data on zinc absorption, secretion, and excretion through use of stable isotopes. Jalla et al determined that healthy infants retain zinc of 0.4 mg/day. We hypothesize that due to increased zinc losses, the infants in the study will be less positive than the healthy infants in the study by Jalla et al. Our study is designed to be able to detect if the ostomy patients net retention is one-half that described by Jalla (i.e. 0.2 mg/d). We will also obtain data on copper absorption, secretion, and excretion through the use of stable isotopes in the second part of the study. As a pilot study, we do not fully know what to expect regarding copper levels in infants with ostomies, but we hypothesize that they may be less positive than healthy infants without ostomies. Also, we hypothesize that zinc and copper are competitively absorbed in the gut; therefore, infants who receive more zinc may absorb less copper. For the third part of the study, we will obtain data on zinc absorption through the use of stable isotopes after the infant has had surgery to reanastamose the bowel. We hypothesize that there may be continued zinc losses above those documented for healthy infants who have never had an ostomy, but decreased losses compared to when the infant had an ostomy. To determine how the presence of an ileostomy impacts zinc and copper metabolism in infants at three time points: 1) when the infant has an ostomy and is receiving the majority of calories from total parenteral nutrition (TPN); 2) when the infant has an ostomy and is receiving primarily enteral nutrition without TPN; and 3) when/if the infant has a surgery to reconnect the bowel and is receiving primarily enteral nutrition. The primary objective of this study revolves around part 2, the stable isotope portion of zinc and copper absorption, secretion, and excretion in infants with an ostomy. There is currently no data available in this population for zinc balance.