Functional and total IGFBP3 for the assessment of disorders of the GH/IGF1 axis in children with chronic kidney disease, GH deficiency, or short stature after SGA status at birth.
OBJECTIVE
IGFBP3 immunoreactivity may appear elevated in patients with chronic kidney disease (CKD), in part due to accumulation of low molecular fragments. The importance of these IGFBP3 variants for binding and inactivation of IGF1 and their relevance for the impaired growth of uremic children are unclear. Nevertheless, IGFBP3, measured as total (t-)IGFBP3, is frequently used as a diagnostic parameter in pediatric CKD patients. A new assay for functional (f-)IGFBP3 exclusively detects IGFBP3 capable of IGF binding. The aim of the study was to evaluate the significance of f-IGFBP3 measurements for the assessment of uremic abnormalities of the GH/IGF1 axis.


METHODS
Prospective cross-sectional study.


METHODS
t-IGFBP3, f-IGFBP3, and IGF1 were measured in pediatric CKD patients, including patients with CKD stage 3-4 not on dialysis (CKD, n=33), on dialysis treatment (DT, n=26), patients after renal transplantation (RTx, n=89), healthy children (n=29), children with GH deficiency (GHD, n=42), and small for gestational age (SGA) children (SGA, n=34).


RESULTS
Mean t-IGFBP3 SDS was elevated in CKD, DT, and RTx children compared with controls and GHD patients (P≤0.0004). Highest values were reached in DT (P<0.0001 vs all groups). In contrast, mean f-IGFBP3 was similar in all groups (P=0.30).


CONCLUSIONS
Pediatric CKD patients displayed elevated serum concentrations of t-IGFBP3 but not f-IGFBP3, supporting the hypothesis that IGFBP3 fragments not binding IGF1 accumulate during uremia. f-IGFBP3 is an indicator of IGFBP3 fragmentation and seems to reflect IGF1 binding in CKD better than t-IGFBP3. However, the role of f-IGFBP3 for the diagnosis of disturbances of the GH/IGF hormonal axis appears to be limited.
Department of Pediatrics II, Pediatric Nephrology, Endocrinology and Diabetology, Gastroenterology and Transplant Medicine, University Children's Hospital, University of Duisburg-Essen, Hufelandstrasse 55, D-45122 Essen, Germany.
A K
AK
Büscher
R
R
Büscher
L
L
Pridzun
M
M
Langkamp
N
N
Wachendorfer
P F
PF
Hoyer
M B
MB
Ranke
B P
BP
Hauffa
D000293:Adolescent; D001827:Body Height / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004393:Dwarfism, Pituitary / Q000097:blood* / Q000453:epidemiology; D005260:Female; D005865:Gestational Age; D006130:Growth Disorders / Q000097:blood* / Q000453:epidemiology; D019382:Human Growth Hormone / Q000097:blood*; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D011446:Prospective Studies; D051436:Renal Insufficiency, Chronic / Q000097:blood* / Q000453:epidemiology
C515497:IGFBP3 protein, human; D018972:Insulin-Like Growth Factor Binding Protein 3; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I