Primary Outcome Measures:
- Serum GH levels in response to GHRH/arginine stimulation [ Time Frame: End of study ] [ Designated as safety issue: No ]
Secondary Outcome Measures:
- mRNA and protein levels of G alpha q and G alpha S stimulatory proteins [ Time Frame: end of study ] [ Designated as safety issue: No ]
- Serum gonadal steroid levels in the three subject groups [ Time Frame: end of study ] [ Designated as safety issue: No ]
Intervention Details:
Procedure: GHRH/arginine stimulation testing
GHRH(Geref) 1mcg/kg IVP followed by Arginine 10% solution 0.5mg/kg (maximum of 30 Gm) infused over 30 minutes. Labs drawn 6 times over 2 hours.
Growth hormone deficiency affects disproportionately more males than females. Although ascertainment bias plays a role in this sexual dimorphism, no plausible mechanism to fully explain this difference has been proposed.
This investigator initiated study will provide currently unavailable data on sexual/age differences in response to GH stimulation testing. Data obtained from the study may provide a basis for developing appropriate normal ranges for adult GH testing, may provide a plausible mechanism for the enhanced hormone responsiveness observed in females, and may provide data on when the sexual differences to GH stimulation may develop.
The objectives of this study are to:
- Confirm the sexual dimorphism in growth hormone responses for adult growth hormone testing in healthy male and female subjects
- Correlate peak Growth Hormone Releasing Hormone (GHRH)/arginine induced growth hormone responses with G protein levels in healthy subjects and in patients with a history of childhood GH deficiency
- Determine whether sexual dimorphism is acquired during puberty