Journal of Developmental Origins of Health and Disease

Brief Report

Reduced nephron endowment in the neonates of Indigenous Australian peoples

Y. Kandasamya1a2 c1, R. Smitha2, I. M. R. Wrighta2a4 and E. R. Lumbersa2a3

a1 Department of Neonatology, The Townsville Hospital, Queensland 4814, Australia

a2 Mothers and Babies Research Centre, Hunter Medical Research Institute, John Hunter Hospital, Locked Bag 1, Hunter Region Mail Centre, Newcastle, NSW 2310, Australia

a3 School of Biomedical Sciences and Pharmacy, University of Newcastle, NSW 2310, Australia

a4 Graduate School of Medicine, University of Wollongong, Wollongong, NSW 2522, Australia

Abstract

Rates of chronic kidney disease (CKD) among Indigenous groups in Australia exceed non-Indigenous rates eight-fold. Using kidney volume as a surrogate for nephron number, we carried out a study to determine if Indigenous neonates have a smaller kidney volume (and thus a reduced nephron number) from birth compared with non-Indigenous neonates. We recruited term and preterm neonates (<32 weeks) at a tertiary care neonatal unit over a 12 months period. Preterm neonates were assessed (renal sonography and renal function measurement) at 32 weeks corrected age (CA) and again at 38 weeks CA when blood pressure was also measured. All term neonates were assessed in the first post-natal week, including renal sonography, renal function and blood pressure measurement. The primary outcome measured was total kidney volume (TKV) and estimated glomerular filtration rate (eGFR) was a secondary outcome. Data was available for 44 preterm (11 Indigenous) and 39 term (13 Indigenous) neonates. TKV of Indigenous neonates was significantly lower at 32 weeks [12.0 (2.0) v. 15.4 (5.1) ml; P=0.03] and 38 weeks CA [18.6 (4.0) v. 22.6 (5.9) ml; P=0.04] respectively. Term Indigenous neonates also had smaller kidney volumes compared with non-Indigenous neonates. Despite a smaller kidney volume (and reduced nephron number), Indigenous neonates did not have a significantly lower eGFR. Indigenous neonates achieve similar eGFRs to Non-Indigenous neonates, presumably through a higher single nephron filtration rate. This places Indigenous neonates at a greater risk of long-term kidney damage later in life.

(Received August 17 2013)

(Revised October 06 2013)

(Accepted October 14 2013)

(Online publication November 08 2013)

Key words

  • hyperfiltration;
  • Indigenous;
  • kidney volume;
  • low birth weight;
  • preterm

Correspondence

c1 Address for correspondence: Dr Y. Kandasamy, MBBS, PhD, FRACP, Department of Neonatology, The Townsville Hospital, 100 Angus Smith Drive, Douglas, Queensland 4814, Australia. (Email: dryoga1@bigpond.com)

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