phenylalanine) should be avoided in liver disease. In renal failure, only essential
amino acids are given, in order to avoid excessive production of urea, which
requires renal excretion. Endogenous nitrogen sources are used to form the
non-essential amino acids. Arginine supports immune function (T-cells) and also
stimulates insulin production, which is anabolic.
Both calcium and phosphorus are essential for skeletal development and
maintenance. Premature infants are deficient in calcium and phosphorus and
have significant requirements. Potential precipitation of calcium with anions
requires careful adjustments in parenteral nutrition. The calcium to phosphorus
ratio should be optimized to provide for bone development and health. The ideal
ratio is a 1:1 ratio of 2 mEq/1 kg/day of calcium to 2 mM/kg/day of phosphorus.
Ratios can range from 2:1 to 0.5:1. A 10% calcium gluconate solution is typically
used providing 1 mEq of calcium, which equals 200 mg of calcium gluconate.
Calcium intake recommendations are 1 to 3 mEq/kg/day for maintenance and 3
to 5 mEq/kg/day for growth. Phosphorus intake recommendations are 1.3
mM/kg/day for maintenance and 2 mM/kg/day for growth. Ionized calcium
concentrations should range from 4.5 to 5.3 mg/dL. Hypocalcemia is common in
premature infants, asphyxiated infants, infants of diabetic mothers and infants of
hypoparathyroid mothers. Symptoms include include irritability, jitteriness and
seizures. Symptomatic or extremely low birth weight infants should have early
supplementation. Central venous access is preferred because of soft tissue
injuries that can occur with peripheral venous infiltration.