Results of 1-year growth hormone (GH)-releasing hormone-(1-44) treatment on growth, somatomedin-C, and 24-hour GH secretion in six children with partial GH deficiency.

Six children with short stature and partial GH deficiency in response to two pharmacological tests received GHRH for 12 months (10 micrograms/kg X day, sc) each evening. Twenty-four-hour GH secretion was studied before and after 3 and 12 months of treatment, and GHRH tests (2 micrograms/kg, iv) were done before and after 6 months of treatment. Plasma somatomedin-C was measured before and after 1.5, 3, 6, 9, and 12 months of treatment. Statural growth was measured at 3-month intervals. Mean growth velocity increased from 4.2 to 8.6 cm/yr, with a good result in five children and no response in the other. The growth response was substantial during the first 3 months. It was maintained during the following 6 months, and then decreased during the last 3 months. The peak plasma GH level in response to GHRH increased from 34.5 +/- 14.2 (+/-SD) ng/mL before treatment to 47.8 +/- 3.4 ng/mL after 6 months of treatment. Twenty-four-hour GH secretion increased in all parameters at 3 months (maximum peak, area under the curve, integrated concentration, and number of peaks) and at 12 months (with the exception of the maximum peak). Nycthemeral secretory profiles became normal, with reappearance of secretory pulses in two children, slight increases in three children, and no change in one child. Plasma somatomedin-C levels rose from 0.8 +/- 0.3 U/mL before treatment to 2.0 +/- 1.0 U/mL at 3 months, then decreased to 1.3 +/- 0.6 U/mL at 12 months. These results indicate that GHRH administered by sc injection for a 1-yr period stimulated growth and GH secretion. However, a decrease in activity was noted during the last 3 months of treatment. Tests for anti-GHRH antibodies were positive in the only child who did not respond to treatment.