RESPONSE OF GROWTH HORMONE DEFICIENT PATIENTS TO SYNTHETIC GROWTH HORMONE-RELEASING FACTOR

Abstract

We studied the growth hormone (GH) response to synthetic growth hormone-releasing factor (GRF (1-44)-NH2)† in non-GH deficient (NGHD) subjects (4-33 yrs) and GH deficient (GHD) patients (5-24 yrs). The mean (±SE) peak GH response of 6 NGHD children after 5 μg/kg IV of GRF (27.1±5.8 ng/ml) was similar to that of NGHD young men previously reported (JCEM 57:677). Of 20 patients with severe GH deficiency 17 responded to 5 μg/kg IV of GRF, but the mean peak plasma GH concentration was less than that of the NGHD group (5.0±1.2 vs 27.2±3.5 ng/ml; p<0.001). Patients with isolated GH deficiency had responses similar to those with multiple pituitary hormone deficiencies. The GH responses of the GHD children correlated negatively with chronologic age (r= −0.758, p<0.02). Six partially GHD children had a higher GH response to GRF than severely GHD children (13.1±1.8 vs 6.9±1.7 ng/ml; p<0.04) but lower than NGHD children (p<0.05). GRF induced higher plasma GH levels in GHD than did arginine, insulin, or L-dopa.

The GRF test is useful for assessing GH reserve. Although a GH response to GRF in GHD patients suggests GRF deficiency, the lack of response does not exclude it. The GH response to synthetic GRF in many GHD children is consistent with a hypothalamic abnormality as the etiology of their GH deficiency and supports the potential therapeutic usefulness of GRF or an analog in these patients.

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