Comparison of growth hormone response to growth hormone-releasing factor 1-44 according to the combined study of sleep secretion with the responses to pharmacologic stimuli

The growth hormone (GH) response to GH-releasing factor (GRF) was studied in 54 severely growth-retarded patients (-2.1 to -6.5 SD) aged from 5 to 20 years (32 males and 22 females), among whom 34 were prepubertal and 20 at early pubertal stages. The patients were also submitted to a standard evaluation of their GH secretion, consisting of at least two classical pharmacologic stimulation (CPS) tests, such as ornithine, arginine and/or insulin, and one study of the GH sleep secretion (SS). The results of the standard evaluation allowed to distinguish 5 groups: (I) endocrinologically normal (n = 26); (II) completely GH deficient (n = 5); (III) partially GH deficient (n = 8); (IV) dissociated GH secretions with normal SS (n = 9), and (V) dissociated GH secretions with low SS (n = 6). The GH responses to GRF were correlated with both responses to CPS and SS. There was a large overlap of the individual responses to GRF between the 5 groups, but the mean responses in groups II, IV and V were significantly lower than in group I. Furthermore, the mean responses of groups IV and V were in the lower range of the normal. It is concluded that the GRF test may be useful to ascertain the diagnosis of functional or partial GH deficiency when the responses to CPS and SS are dissociated.