Metabolic and hormonal responses of low birthweight infants to intravenously infused calories not exceeding the maintenance energy expenditure.

Eithe low birthweight infants were studied for their metabolic and hormonal responses to intravenous alimentation when the caloric input was varied. The study was made during three consecutive 12-hour periods, when solutions of glucose, glucose and amino-acids, and glucose and amino-acid and lipids were successively infused. Hypertonic glucose led to a fall in plasma free fatty acids and amino-acids. Supplementation with an amino-acid mixture increased the concentration of amino-acids but not above the fasting level. Thus, hypertonic glucose was an effective means for avoiding hyperaminoacidaemia. Blood urea was little changed, also indicating satisfactory use of amino-acids. The number and distribution of calories infused throughout the third 12-hour period, when lipid was infused, were also important factors contributing to the avoidance of hyperaminoacidaemia. The caloric needs of low birthweight infants kept at neutral temperatures should be individually assessed in the light of recent data. The administration of an unnecessarily large load of calories and nutrients to parenterally-fed infants can thereby be avoided.