AIM: When a new high amino acid parenteral nutrition (PN) solution was introduced to our hospital, a design error led to decreased phosphate levels. This prompted us to examine the effect of three different PN solutions on plasma phosphate, plasma calcium and weight increases on extremely preterm infants.

METHOD: This was a retrospective study of 186 infants with a gestational age of <28 weeks during their first month of life. They were divided into three groups based on the PN they received during hospitalisation. Group one received high levels of phosphate and low levels of amino acids. Group two received low levels of phosphate and high levels of amino acids. Group three received high levels of both phosphate and amino acids.

RESULTS: The lowest plasma phosphate values varied significantly between groups one (1.80 ± 0.46 mmol/L), two (1.05 ± 0.48 mmol/L) and three (1.40 ± 0.37 mmol/L) (p < 0.001), but no significant difference in weight increase was seen (p = 0.497).

CONCLUSION: The phosphate content of the PN influenced plasma phosphate and plasma calcium levels, but increasing the levels of both phosphate and amino acids did not improve weight gain during the first month of life.