Increase of serum growth hormone-binding protein in patients with ossification of the posterior longitudinal ligament of the spine.

Serum growth hormone-binding protein (GHBP) was measured in 26 patients with ossification of the posterior longitudinal ligament of the spine (OPLL) and 19 age-matched controls. Serum GHBP level was significantly higher in the OPLL group than in the controls, whereas there was no statistical difference between the two groups in serum level of growth hormone, insulin-like growth factor (IGF)-1, and IGF-2. These results, taken together with the hypothesis that serum GHBP reflects the number of GH receptors in tissue, suggest that GH receptors are increased in patients with OPLL.