title: Effect of gestational age and blood glucose on C-peptide excretion rate and clearance in neonates.
abstract: OBJECTIVE
  The aim of this study was to measure urinary C-peptide concentrations, and then calculate C-peptide clearance (Cl), and excretion rate (UER) in neonates. In addition, the effect of gestational age (GA) and blood glucose levels (BGL) on C-peptide UER were investigated.
  
  
  METHODS
  Insulin concentrations in plasma and C-peptide concentrations were measured in plasma and urine, in 20 neonates. Chemiluminescent immunoassays were used for insulin and C-peptide measurements, with urine diluted to 40% with bovine serum albumin 1% in phosphate buffered saline. Urine volume and time of collection were recorded and used to calculate UER and Cl.
  
  
  RESULTS
  The mean Cl of C-peptide was 0.309 ± 0.329 mL/min/kg, and UER was 0.0329 ± 0.0342 pmol/min/kg. Correlations between Cl or UER and GA were not significant (P > 0.05). No significant correlation was shown between Cl or UER and BGL (P > 0.05).
  
  
  CONCLUSIONS
  Both Cl and UER were highly variable in neonates, but were not correlated with GA. Additionally, BGL did not appear to affect C-peptide UER and Cl. As GA and BGL did not appear to affect Cl and UER, urinary C-peptide may provide a non-invasive method of measuring insulin production in neonates.
authors.affiliation: New Zealand's National School of Pharmacy, University of Otago, Dunedin, New Zealand.
authors.forename: Emma R
authors.initials: ER
authors.lastname: Salis
authors.affiliation: Department of Pharmacy, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Mikkel K
authors.initials: MK
authors.lastname: Soelbeck
authors.affiliation: Department of Women's and Children's Health, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand.
authors.forename: David M
authors.initials: DM
authors.lastname: Reith
authors.affiliation: Department of Women's and Children's Health, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Wheeler
authors.affiliation: Department of Women's and Children's Health, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand.
authors.forename: Roland S
authors.initials: RS
authors.lastname: Broadbent
authors.affiliation: New Zealand's National School of Pharmacy, University of Otago, Dunedin, New Zealand.
authors.forename: Natalie J
authors.initials: NJ
authors.lastname: Medlicott
mesh_terms: D001786:Blood Glucose / Q000378:metabolism*; D002096:C-Peptide / Q000097:blood* / Q000493:pharmacokinetics; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D049449:Luminescence; D008297:Male
chemical_list: D001786:Blood Glucose; D002096:C-Peptide
keywords: C-peptide; chemiluminescence; clearance; excretion rate; insulin; neonate