RATIONALE: Very low birth weight infants have problems maintaining normal blood sugar
levels. Gluconeogenesis is the production of sugar from amino acids and fats. The best
combination of amino acids, fat, and sugar to help very low birth weigh infants maintain
normal blood sugar levels is not yet known.
PURPOSE: Clinical trial to study how very low birth weight infants break down amino acids,
fat, and sugar given by intravenous infusion, and the effect of different combinations of
nutrients on the infants' ability to maintain normal blood sugar levels.
PROTOCOL OUTLINE: Patients are assigned to one of 6 study groups.
Patients receive infusions of stable isotope tracers: [15N]urea IV beginning at -12 hours
and continuing over 22 hours to measure protein oxidation; [U-13C]glucose IV beginning at
zero hour and continuing over 10 hours to measure glucose appearance rate and
gluconeogenesis; [2-13C]glycerol IV over 10 hours to measure lipolysis; and [1-C]leucine IV
over 10 hours to measure proteolysis. Blood samples are obtained before the start of the
urea tracer infusion; before the start of the glucose, glycerol, and leucine tracer
infusions; and at study hours 4, 4.5, 5, 9, 9.5, and 10. Blood glucose is measured hourly,
and patients receive glucose IV if blood glucose falls below 40 mg/dL.
Group I: Patients are randomized to one of two study arms. Arm I: Patients receive
standard total parenteral nutrition (TPN), except the [U-13C]glucose is substituted
for a portion of the glucose. Arm II: The infusions of lipids (Intralipid) and amino acids
(TrophAmine) are discontinued at study hour zero. The infusion rate of natural
glucose will be reduced during the first hour, and thereafter discontinued.
Group II: Patients are randomized to receive either TrophAmine or Intralipid IV over the
last 5 hours of the study.
Group III: Patients are randomized to receive one of two different doses of glycerol IV
over the last 5 hours of the study.
Group IV: Patients are randomized to receive either glutamine or alanine IV over the last 5
hours of the study.
Group V: Patients receive glucagon IV for 24 hours prior to study. Patients are then
randomized to receive glucagon IV with either IV glucose alone or with Intralipid and
Group VI: Patients who are hyperglycemic receive TPN and [U-13C]glucose as in group I, arm
I, over 14 hours, and regular insulin IV at 10 hours, followed by an IV infusion of
carbohydrate. Blood samples obtained between hours 4 and 5 are omitted, and are drawn
instead between hours 13 and 14.
- Clinically stable, very low birth weight infants (750-1,500 grams)
- Normal blood glucose values OR Blood glucose greater than 175 mg/dL
- No prior insulin
- No sepsis Oxygen supply less than 30% Normal acid base status
- No malformation
- No discernible diseases