Repetitive Injections of Growth Hormone Releasing Hormone (GHRH 1-44) to Normal Volunteers and Patients with Growth Hormone Deficiency

Abstract

The present study was designed to answer the following three questions: Is there any difference between the growth hormone (GH) response to i.v. injections of GHRH 1-44 by a slowly injecting hormone pump or to a s. s. or rapid i. v. injection by syringe? Do nocturnal injections of GHRH 1-44 i. v. elicit different GH levels than during daytime? Can repetitive administration of GHRH 1-44 in patient with GH deficiency induce a physiological GH pattern and thereby normalize the condition resulting from a hypothalamic defect? A rapid i. v. bolus injection of 50 micrograms GHRH 1-44 by syringe with an injection time of one second elicited in the same subject at the same time of the day a twofold greater response than a slowly injecting (60 seconds) hormone pump. In six male adult volunteers each GHRH i. v. bolus was followed by a GH secretory pulse. The GH response at night (area under the curve and peak plasma GH levels) was significantly greater than at daytime (P less than 0.05) and greater than the GH pulses measured during a spontaneous nocturnal profile (P less than 0.05). Out of six GH deficient young adult patients who had been receiving extractive GH until two years prior to the study, three responded much like the controls, the other three patients-those who lacked any spontaneous nocturnal GH peaks-had markedly lower GH levels after GHRH (P less than 0.05). However, there was a clear-cut GH release after GHRH injection in each patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Repetitive Injections of GHRH in Normal Children and Adults

“…The different GH responsiveness of adults and children may reflect an age-dependent different mode of neuroendocrine control. It is therefore likely that the discrepancy between the findings of Hummelink and Sippel (1990) and those observed in our studies could be due to the extremely low GH response ( < 5 ng/ml in 3 out of 6 cases) to the first GHRH administration in their normal adults (as shown in their Figure 3). In our experience, normal adults, although with a wide range of variability, show GH responses to GHRH higher than 10 ng/ml.…”

“…In our experience, normal adults, although with a wide range of variability, show GH responses to GHRH higher than 10 ng/ml. The reduced GH response to the first GHRH administration observed in the study of Hummelink and Sippel (1990) might be due to the low dose of GHRH (50 ug iv, 0.61 ± 0.06 |xg/kg b.w.) administered in their normal adults.…”