Synthetic growth hormone-releasing hormone (GHRH 1-44) in the differential diagnosis between hypothalamic and pituitary GH deficiency

Diagnostic value of growth hormone-releasing hormone test in children and adolescents with idiopathic growth hormone deficiency

Average growth hormone (GH) peaks following an i.v. growth hormone releasing hormone (GHRH) 1-29 stimulation test were significantly lower in 48 children and adolescents with GH deficiency (GHD) than in 20 age-matched controls (15.2 + 12.7 vs 37.5 + 28.1 ng/ml, 2 P less than 0.001). Twelve patients exhibited a low GH peak (less than 5 ng/ml), 27 demonstrated a normal response (greater than 10 ng/ml) and 9 showed an intermediate rise in plasma GH (5-10 ng/ml). Six of the 12 patients with low GH response to the first GHRH stimulation failed to respond to two other tests immediately before and after a 1 week priming with s.c. GHRH. These subjects with subnormal GH increase at repeat testing had total GHD (TGHD) and multiple pituitary hormone deficiency (MPHD) and had suffered from perinatal distress. On the contrary, 26 of 27 patients with normal GH response to the first test had isolated GHD and only a minority (8/27) had signs of perinatal distress. It is concluded that perinatal injuries primarily damage pituitary structures and that a pituitary defect more probably underlies more severe forms (TGHD and MPHD) of GHD.

GHRH-test in short children with "non classic" GH deficiency. A comparison with "classic" GH deficiency and short normal stature

In this study GHRH-test has been performed (2 micrograms/Kg of an iv bolus of GHRH 1-44) sampling for GH measurement every 15 min over 2 hours in three groups of short children. Group 1 consisted of 10 subjects with classic GH deficiency (CGHD): GH response less than 10 ng/ml to two conventional tests and 24-h mean GH concentration (MGHC) less than 3 ng/ml; group 2 consisted of 16 subjects with non-classic GH deficiency (NCGHD): response greater than 10 ng/ml to at least one conventional test and MGHC less than 3 ng/ml; group 3 consisted of 18 subjects with short normal stature: GH response greater than 10 ng/ml to at least one conventional test and MGHC greater than 3 ng/ml. GH peak and area under the curve (AUC) values were significantly lower in group 1 than groups 2 and 3 and in group 2 than group 3. GH peak and AUC values statistically correlated with height, height velocity, bone age/chronological age ratio and MGHC. Six children in group 1, 14 children in group 2 and all 18 children in group 3 showed after GHRH a GH peak greater than 10 ng/ml and were considered as 'responders'. Considering only the responders, GH peak and AUC values were significantly lower in group 1 than groups 2 and 3 and in group 2 than group 3. In conclusion, our data have shown that 87% of children with NCGHD responded to a single bolus of GHRH with an increase in GH levels greater than 10 ng/ml and that their responses were intermediate compared to those of CGHD and short normal subjects.

Long term growth hormone (GH)-releasing hormone and biosynthetic GH therapy in GH-deficient children: comparison of therapeutic effectiveness

Twenty-five GH-deficient children were treated with GHRH (1-44), once daily sc for 6-24 months. At the 6th month of therapy, 40% of our patients showed a catch-up growth (responders), while the remaining 60% did not (nonresponders). No differences in auxological and biological variables at inclusion were found between the two groups. However, integrated GH secretion elicited by iv GHRH at inclusion was significantly (p less than 0.025) higher in responders than in non responders. During GHRH therapy, no significant increase in IGF 1/SmC was found in both groups. In all patients treatment was discontinued after 6-24 months, when its effect on growth rate failed. After a wash-out period of at least 6 months, patients were submitted to biosynthetic GH therapy. After 6 months of GH treatment a significant catch-up growth was found in both responder and non-responder children. Although the majority of GH-deficient children have hypothalamic rather than pituitary dysfunction, GHRH therapy is found to be less effective than GH treatment. Other methods of GHRH administration are worth investigating.