Influence of estrogen administration on growth hormone response to GHRH and L-Dopa in patients with Turner's syndrome.

The modulating effect of estrogen on GH secretion was studied in 22 patients with Turner's syndrome. Estrogen administration (0.5 microgram/kg ethinylestradiol) for a period of 4 weeks resulted in a significant increase in basal GH concentrations (2.6 vs 4.8 micrograms/l, P less than 0.01). The L-Dopa-stimulated GH concentrations were also significantly increased (P less than 0.01), whereas no effect of estrogen substitution on GH responses to GHRH (1-44) and Sm-C levels was seen. Our findings demonstrate a priming effect of estrogen on GH secretion in patients with Turner's syndrome. These patients generally lack the puberty-associated rise in GH secretion, which might be due to ovarian failure and the concomitant estrogen deficiency.