No abstract

SUMMARY To assess the effects of increasing the mineral content of parenteral nutrition solutions on the biochemical and radiological indicators of metabolic bone disease of prematurity 27 neonates who required parenteral nutrition were sequentially allocated to receive either a standard solution (group 1) or one with an increased mineral content (group 2). The 13 patients in group 1 received 0-68 mmol/kg/day of calcium and 061 mmollkg/day of phosphorus, and the 14 in group 2 received 1-25 and 1-20 mmol/kg/day, respectively. The two groups did not differ significantly in the severity of their illness measured by birth weight, gestational age, duration of parenteral nutrition or ventilation, or the amount of supplementary oxygen required. In patients in group 2 the median plasma phosphate concentration was higher, the plasma alkaline phosphatase activity was lower, and there was less radiological evidence of rickets. There were no complications caused by excess calcium and phosphorus, and the rate of growth was similar in both groups. We conclude that an increased mineral content in parenteral nutrition solutions reduces the severity of metabolic bone disease in sick infants who require this form of nutrition.Metabolic bone disease is common in premature infants whether they are fed enterally' or parenterally.2 Deficiency in the mineral substrate is thought to be an important aetiological factor,3 though increasing the intake of calcium and phosphorus in enterally fed infants failed to reduce the incidence of rickets.4 In utero accretion of calcium occurs at about 2-75-3-25 mmol/kg/day, and phosphorus at about 2-1-2-6 mmol/kg/day5; conventional intravenous feeding solutions cannot deliver these minerals at these rates without making them insoluble.6 Alternating solutions with either a high calcium or phosphorus concentration has been tried to overcome this problem,7 but this increases the difficulty of feeding, and a fluctuating intake is not physiological.The amount of calcium and phosphorus that can be held in solution without precipitation is decreased if the amino acid concentration is decreased.8 Our standard parental nutrition solution normally delivers calcium and phosphorus at a rate of 0-6-1*0 and 0-7 mmol/kg/day, respectively. If higher rates are attempted, precipitation occurs if the intake of amino acid is reduced. In vitro studies have, however, shown that the intake of calcium and phosphorus can be increased to as much as 2-0 and 1-7 mmollkg/day, respectively, without precipitation if the intake of amino acid (using Vamin-9-glucose, KabiVitrum) is maintained at 50 ml/kg/day (P MacMahon, et al, unpublished observations). We used this to formulate a second parenteral nutrition solution with an increased calcium and phosphorus content without altering the amino acid content. The modified solution with extra calcium and phosphorus was then compared with our previous standard in a controlled trial designed to assess the effects of the increased mineral content of the parenteral nutrition solution on the ...