title: Early postnatal calcium and phosphorus metabolism in preterm infants.
abstract: OBJECTIVE
  Bone mineralisation in preterm infants is related to the supply of calcium (Ca) and phosphorus (P). We increased the amount of minerals in parenteral nutrition (PN) for preterm infants and evaluated postnatal Ca and P metabolism in relation to mineral and vitamin D (vitD) intake.
  
  
  METHODS
  Preterm infants, included on their first day of life, received standard PN, providing a maximum Ca/P intake of 3/1.92 mmol · kg(-1) · day(-1) on day 3. Ca/P content of formula was 2.5/1.6 mmol/dL, and fortified human milk was 2.4/1.95 mmol/dL. PN supplied 80 IU · kg(-1) · day(-1) vitD. Formula and fortified human milk contained 200 IU/dL of vitD. During a 5-week period, serum concentrations and urinary excretion of Ca/P were registered and related to the intake of minerals and vitD.
  
  
  RESULTS
  During 12 months, 79 infants (mean gestational age 29.8 ± 2.2 weeks, mean birth weight 1248 ± 371 g) were included. The recommended intake for minerals was achieved by day 5 and for vitD by 4 weeks. Infants developed hypercalcaemia, hypercalciuria, and hypophosphataemia during the first postnatal week, leading to the additional P supplementation in 49 infants. The renal tubular reabsorption of P was >95% until day 9 but decreased <70% after the second week. Alkaline phosphatase was normal at birth, increased to a maximum of 450 IU/L by day 14, and remained above the normal range for the remaining period.
  
  
  CONCLUSIONS
  Parenteral intake of P appeared to be too low, leading to mineral imbalances in the early postnatal period, and vitD intake was also below recommendations.
authors.affiliation: *Department of Paediatrics, Subdivision of Neonatology, Radboud University Medical Centre, Nijmegen †Department of Paediatrics, Leiden University Medical Centre, Leiden ‡Department of Paediatrics, Medisch Spectrum Twente, Enschede §Department of Paediatrics, VU University Medical Centre, Amsterdam, The Netherlands.
authors.forename: Viola
authors.initials: V
authors.lastname: Christmann
authors.forename: Anne M
authors.initials: AM
authors.lastname: de Grauw
authors.forename: Reina
authors.initials: R
authors.lastname: Visser
authors.forename: René P
authors.initials: RP
authors.lastname: Matthijsse
authors.forename: Johannes B
authors.initials: JB
authors.lastname: van Goudoever
authors.forename: Arno F J
authors.initials: AF
authors.lastname: van Heijst
mesh_terms: D000469:Alkaline Phosphatase / Q000097:blood; D001942:Breast Feeding; D002118:Calcium / Q000008:administration & dosage / Q000378:metabolism*; D005527:Food, Fortified; D006706:Homeostasis; D006801:Humans; D006934:Hypercalcemia / Q000097:blood / Q000628:therapy; D053565:Hypercalciuria / Q000628:therapy / Q000652:urine; D017674:Hypophosphatemia / Q000097:blood / Q000628:therapy; D041943:Infant Formula; D007231:Infant, Newborn; D007234:Infant, Premature / Q000378:metabolism*; D007684:Kidney Tubules / Q000378:metabolism; D008895:Milk, Human; D010288:Parenteral Nutrition; D010758:Phosphorus / Q000008:administration & dosage / Q000378:metabolism*; D011446:Prospective Studies; D013997:Time Factors; D014807:Vitamin D / Q000008:administration & dosage*; D014815:Vitamins / Q000008:administration & dosage*
chemical_list: D014815:Vitamins; D014807:Vitamin D; D010758:Phosphorus; D000469:Alkaline Phosphatase; D002118:Calcium