Pediatric Nephrology

, Volume 25, Issue 4, pp 659–667

The IGF/IGFBP system in relation to macroscopic bone architecture in pediatric renal transplant patients

  • Daniela Kiepe
  • Eva-Maria Rüth
  • Werner F. Blum
  • Subburaman Mohan
  • Lutz T. Weber
  • Burkhard Tönshoff
Original Article

DOI: 10.1007/s00467-009-1405-5

Cite this article as:
Kiepe, D., Rüth, E., Blum, W.F. et al. Pediatr Nephrol (2010) 25: 659. doi:10.1007/s00467-009-1405-5

Abstract

The post-transplant bone disease of the peripheral skeleton in pediatric renal transplant recipients is characterized by an inadequately thin bone cortex in relation to muscular force. A major hormonal modulator of periosteal growth is the insulin-like growth factor (IGF)/IGF binding protein (IGFBP) system. We therefore hypothesized that the reduced cortical thickness in these patients may be due to functional IGF deficiency. To test this hypothesis, we investigated 55 patients (mean estimated glomerular filtration rate 86.3 ± 30.0 ml/min/1.73 m2) in a cross-sectional study. Parameters of macroscopic bone architecture and forearm muscle size were analyzed by peripheral quantitative computed tomography (pQCT), and serum IGF/IGFBP system components were measured by specific radioimmunoassays. The mean (± standard deviation) standardized serum IGF-I (0.20 ± 1.16 score) level was normal, while the mean IGF-II (1.16 ± 0.11 score) level was significantly elevated. Serum IGFBP-1 and IGFBP-2 levels were not altered, whereas the IGFBP-3 (1.34 ± 0.15 score) level was significantly increased. The serum IGFBP-4 level was slightly elevated (by 11%), the IGFBP-6 level was markedly (2.3-fold) elevated, while the IGFBP-5 level was comparable to that of the control. The respective age-adjusted cortical thickness at both the proximal (r = 0.407, P < 0.005) and distal (r = 0.383, P < 0.01) forearm was positively correlated with the standardized serum IGF-I level. In conclusion, the serum IGF/IGFBP system in pediatric renal transplant recipients is characterized by an increase in the levels of the inhibitory IGFBPs, IGFBP-3, -4 and -6, resulting in a functional IGF deficiency. The positive correlation of IGF-I with cortical thickness underlines the importance of this hormonal system in the modeling of bone, particularly periosteal growth.

Keywords

IGF/IGFBP systemPediatric renal transplant recipientsPeripheral quantitative computed tomographyPost-transplant bone disease

Copyright information

© IPNA 2009

Authors and Affiliations

  • Daniela Kiepe
    • 1
  • Eva-Maria Rüth
    • 1
    • 2
  • Werner F. Blum
    • 3
  • Subburaman Mohan
    • 4
  • Lutz T. Weber
    • 1
    • 5
  • Burkhard Tönshoff
    • 1
  1. 1.University Children’s HospitalHeidelbergGermany
  2. 2.Department of Pediatric NephrologyUniversity Hospital ErlangenErlangenGermany
  3. 3.Lilly Research LaboratoriesEli Lilly & Co.Bad HomburgGermany
  4. 4.Musculoskeletal Disease CenterJerry L Pettis Memorial Veterans Affairs Medical CenterLoma LindaUSA
  5. 5.Pediatric Nephrology, Dr. von Haunersches Kinderspital, University Children’s Hospital Ludwig-Maximilian’s UniversityMunichGermany