Abstract
The major SmBP in serum is a 150 kD glycoprotein. Its acid-stable subunit was isolated from human plasma Cohn fraction IV by a 3 steps procedure. With the purified protein a RIA was developed which recognizes the complete 150 kD complex in nativ serum. In normal controls there was a considerable increase from 25.7 nmol/l (median, range 14.7 - 44.7) in newborns to 49.4 nmol/l (28.8 - 84.7) after 8 weeks of age. Thereafter SmBP increased continuously to 110.5 nmol/l (77.9 - 156.9) at puberty and declined to 98.9 nmol/l (73.4 - 132.9) in adults. Correlation with IGF-I and IGF-II (by RIA) was non-linear. The sum of both IGF-I and IGF-II correlated linearly with SmBP (r= 0.89) with a regression line intersecting the abscissae at 19.7 nmol/l (about 148 ng/ml) of total IGF-I and -II. In 70 patients with GHD (max. GH < 10 ng/ml in 2 standard tests) 68 had subnormal levels of SmBP (mean SDS for age: -5.52). SmBP increased significantly on treatment with hGH.
Conclusions: 1. The 150 kD SmBP is the major BP form in postnatal life. 2. Total serum Sm levels (IGF-I + IGF-II) are primarily determined by SmBP concentration. 3. SmBP is strongly GH dependent. 4. SmBP is a more specific parameter for the diagnosis of GHD compared to IGF-I or -II particularly below age 5.
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Blum, W., Ranke, M., Kietzmann, K. et al. 31 SOMATOMEDIN BINDING PROTEIN (SmBP) IN NORMALS AND IN GROWTH HORMONE DEFICIENCY (GHD). Pediatr Res 24, 522 (1988). https://doi.org/10.1203/00006450-198810000-00052
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DOI: https://doi.org/10.1203/00006450-198810000-00052
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