Abstract
We report a case of partial GH insensitivity syndrome. A 10-year-old boy was referred to the National Iwakuni Hospital with the chief complaint of short stature. His height was 116.7 cm (-3.65 SD), body weight 17.2 kg, and recent growth velocity (GV) 3.1 cm/year (-2.61 SD). After two provocation tests (L-dopa and clonidine), the basal and peak GH levels were 0.29 ng/ml and 12.26 ng/ml, and 0.48 ng/ml and 12.27 ng/ml, respectively. His 24-h urinary GH concentration was 41.9 pg/mgCr. These data indicate normal GH secretion. In contrast, both his serum IGF-I level and IGF-binding protein 3 (IGFBP-3) level were low at 46 ng/ml and 1.80 μg/ml, respectively. His serum GH-binding protein (GHBP) level was also low at 62.0 pmol/l. These findings may imply partial GH insensitivity due to a defect at the level of the GH receptors (GHR). GH therapy led to an increase in GV from 3.1 to 6.4 cm/year, of the serum IGF-I level from 46 to 110 ng/ml and of serum IGFBP-3 from 1.80 to 2.23 μg/ml after 1 year. On the other hand, the serum GHBP level decreased from 62.0 to 39.6 pmol/l, and the second-year GV did not decrease. Although the reason why the GHBP level decreased is unclear, the constant GV during the second-year treatment may be due to the relatively optimal serum GH level maintained by the reduction in GHR and the administration of exogenous GH.
