IGF binding protein 3 in patients with Laron type dwarfism: effect of exogenous rIGF-I.
OBJECTIVE
The aim of the study was to investigate the serum levels of IGFBP-3, the major IGF-I binding protein, in patients with Laron type dwarfism (LTD) before and after IGF-I treatment.


METHODS
Eight Laron type dwarfism patients (four children and four adults) were treated for 7 days by one daily s.c. injection of biosynthetic IGF-I in doses of 120 or 150 micrograms/kg/day.


METHODS
Blood was sampled in the fasting state before and 1 and 7 days after the last injection.


RESULTS
It was found that IGF-I administration significantly reduced plasma hGH levels with recovery after one week of no treatment. Serum IGFBP-3 was abnormally low (0.70 +/- 0.37 mg/l) and decreased significantly further during IGF-I treatment (to 0.48 +/- 0.28 mg/l) (P less than 0.065).


CONCLUSIONS
The finding that serum IGFBP-3 is low in Laron type dwarfism, a disease due to molecular defects in the GH receptor, is compatible with the hypothesis that this IGF binding protein is GH-dependent. On the other hand the decrease during IGF-I administration and concomitant suppression of GH secretion may denote either that GH activity is not completely blocked in this syndrome or that there are additional mechanisms regulating IGFBP-3 synthesis.
Laron
Z
Z
Institute of Pediatric and Adolescent Endocrinology, Children's Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Israel.
Klinger
B
B
Blum
W F
WF
Silbergeld
A
A
Ranke
M B
MB
D000293:Adolescent; D000328:Adult; D002352:Carrier Proteins / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D004392:Dwarfism / Q000097:blood* / Q000188:drug therapy; D005260:Female; D013006:Growth Hormone / Q000097:blood; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000627:therapeutic use*; D008297:Male; D011994:Recombinant Proteins / Q000627:therapeutic use; D013002:Somatomedins / Q000032:analysis*
D002352:Carrier Proteins; D018969:Insulin-Like Growth Factor Binding Proteins; D011994:Recombinant Proteins; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone