[Changes in osteocalcin serum levels in children with growth hormone deficiency during substitution therapy]

Osteocalcin (OC), a specific marker of osteoblast activity, was measured in 21 short, growth hormone deficient (GHD) children before and during 2 years of growth hormone (GH) therapy. Anthropometric and serum measurements were performed in every three-month during the first year (15 patients) and after the second year (16 patients). Mean OC concentration was significantly lower in GHD children compared to normal value (11.9 +/- 2.1 ng/ml (n = 15) and 11.4 +/- 2.5 ng/ml (n = 16) vs. 17.5 +/- 4.9 ng/ml). During the GH treatment serum OC increased continuously: 15.5 +/- 2.4 - 20.5 +/- 8.2 - 26.1 +/- 8.6 - 25.1 +/- 9.8 ng/ml (n = 15) and 24.9 +/- 9.1 ng/ml (n = 16) then decreased (16.6 +/- 9.7 ng/ml). OC level measured in the 9th and 12th months was markedly higher than in normal children (p = 0.01 and p < 0.001).

1. Serum OC is low in short statured GHD children. 2. In the first 9-12 months of GH therapy OC raises continuously exceeding the normal mean value. 3. During the second year of GH treatment OC decreases to the normal level. 4. OC concentration measured does not correlate with change of other parameters observed (growth velocity, bone maturation, height for age). 5. Although OC is a sensitive marker of bone formation, it has no prognostic value concerning the growth.