Familial short stature with very high levels of growth hormone binding protein.

We report a familial syndrome of short stature associated with partial GH resistance and very high levels of GH binding protein (GHBP). In three individuals of the same family, presenting with growth failure, high circulating GH levels, both basal and stimulated, were found. Insulin-like growth factor-1 plasma levels were either normal or in the low normal range. GH binding activity was extremely elevated in the plasma of the three subjects, with very high maximum binding capacity (30- to 110-fold higher than that of normal adult plasma) and normal binding affinity (5-7.4 x 10(8) M-1). The cause and the exact consequences of the very high level of plasma GHBP, resulting in a low proportion of free circulating GH, remain to be clarified. The short stature and the partial GH resistance are probably related to high GHBP levels.