We've known for a while that growth hormone deficiency (GHD) and sex steroid deficiency are individually associated with low bone mineral density (BMD).
In a study published this month in the Journal of Clinical Endocrinology & Metabolism , the authors analyzed the 15,000+ GHD patients from 31 countries being followed in the KIMS database and found 1,218 men & women who had not yet received growth hormone replacement. They then analyzed these patients' BMD and sex steroid levels. Not surprisingly, in those GHD patients who had lower IGF-1 & sex steroid levels also had lower BMD.
Individually we have studies demonstrating an increase in BMD when GHD patients are given growth hormone and when sex steroid deficient patients are given sex steroids. What we're lacking is a study that demonstrates benefit from giving both growth hormone & sex steroids to those patients deficient in both. Somehow I doubt that the findings from such a study are going to surprise any of us.