We prospectively studied two groups of GH-deficient patients during GH ther
apy based upon exposure of the liver to elevated (oral estrogen) or not ele
vated (endogenous or transdermal) sources of estrogen. We wondered whether
higher concentrations of estrogen at the liver level (oral estrogen) might
inhibit insulin-like growth factor I (IGF-I) secretion and alter exogenous
GH requirements. In this study we compared GH replacement requirements in t
hese two groups of women as well as with GH-treated adult hypopituitary mal
es. The final GH dose was based upon maintenance IGF-I levels in the mid- t
o high normal range adjusted for age and sex or symptom tolerance. Each gro
up [women taking oral estrogen (n = 12), women not taking oral estrogen (n
= 13), and men (n = 12)] was similar in age and final IGF-I concentration.
Women taking oral estrogen required 10.6 +/- 0.7 mu g/kg.day or 867 +/- 45
mu g/day GH, women not taking oral estrogen required 5.0 +/- 0.7 mu g/kg.da
y or 424 +/- 57 mu g/day, and men required 4.1 +/- 0.6 mu g/kg.day of 376 /- 49 mu g/day to achieve similar IGF-I concentrations. GH requirements in
men were not different from those in women not taking oral estrogen, but th
e GH requirements in both groups were significantly different from GH requi
rements in women taking oral estrogen. These observations may be useful in
anticipating appropriate starting and final doses of GH in adult hypopituit
ary patients.