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

Study Overview
=================
Brief Summary
-----------------
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.

Conditions
-----------------
Liver Disease

Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: 24 weeks < gestational age < 32 weeks; 500 g ≤ birth weight < 1250 g; parenteral nutrition with vegetable oil-based lipid emulsions from the first hours of life; diagnosis of cholestasis during vegetable oil-lipid infusion (plasma conjugated bilirubin value > 1 mg/dl) parental consent; Exclusion Criteria: severe malformations; inborn errors of metabolism; severe congenital sepsis; normal liver functions (plasma conjugated bilirubin under 1 mg/dl during vegetable oil-lipid infusion).

Ages Eligible for Study
-----------------
Minimum Age: 24 Weeks
Maximum Age: 32 Months

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------
What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change of plasma phytosterol concentrations in preterm infants during parenteral nutrition and after only intravenous lipid stopping | Plasma campesterol, stigmasterol and sitosterol concentrations will be measured at 7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77 and 84 days from PN started. Plasma phytosterol concentrations will be measured by gas chromatography-mass spectrometry. Calibration curves will be used to calculate the phytosterol plasma concentrations (mg/L). | 7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77 and 84 days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Liver dysfunction in preterm infants will be defined by conjugated bilirubin values from blood samples over 1 mg/dl | Eligibility of preterm infants will be related to liver function. Conjugated bilirubin value from blood sample is a good sign of hepatic function. The threshold value was defined to 1 mg/dl. Just preterm infants who will have conjugated bilirubin values more of 1 mg/dl will be included in the study. Conjugated bilirubin will be measured at 7 and 42 days of life on routine care. When the conjugated bilirubin value will be higher than 1 mg/dl, the analysis will be repeated every 15 days until it returns under the threshold value (1 mg/dl). Parenteral nutrition-associated cholestasis will be only diagnosed in patients with pathological values of conjugated bilirubin (over 1 mg/dl) during vegetable oil-lipid infusion. | Routinely checked at 7 and 42 days of life. Additional measure of conjugated bilirubin will be performed after 15 days if the value continues to be higher than 1 mg/dl. | 
| Plasma phytosterols half-lives | Plasma phytosterol half-lives (days) will be measured using 3 or more plasma phytosterol concentrations calculated after only lipid stopping. Half-life of plasma phytosterols will be calculated from monoexponential decay curves. | We will able to measure the plasma phytosterol half-lives (days) after the analysis of 3 or more blood samples collected from the stop of lipid infusion to 84 days of life |