Half-life of Plasma Phytosterols in Very Low Birth Weight Preterm Infants With Parenteral Nutrition-associated Cholestasis

Parenteral nutrition-associated cholestasis (PNAC) is one of the most common complications resulting from administration of parenteral nutrition in neonates. Excess intravenous intake of vegetable oil-based lipid emulsions containing phytosterols is felt to be a major contributing factor. To date, no information is available on plasma phytosterols half-lives in very-low-birth-weight (VLBW) preterm infants with PNAC. In a prospective cohort study, plasma phytosterols (campesterol, stigmasterol and sitosterol) of VLBW preterm infants with PNAC will be measured by gas chromatography-mass spectrometry (GC-MS) during PN administration and also after the stop of intravenous lipid infusion. Plasma phytosterols half-lives will be calculated from the monoexponential decay curves. Blood samples will be weekly collected from 1st to 12th week of life during routine metabolic tolerance analysis or gas-analysis in order to avoid burden of additional phlebotomy. Samples will be collected in ethylenediaminetetraacetic acid-tubes and immediately centrifugated. Plasma will be stored in pyrogallol added-tubes at -20°C until analysis. Saponification reaction will be done using 5-alpha-cholestane as internal standard.