Hypo-oestrogenic states and bone density
Osteoporosis is emerging as an important public health problem at an enormous cost to the National Health Service. This thesis observes the effects of certain states of hypo-oestrogenism, seen naturally during breast feeding and after the menopause, and the pathological states seen in hyperprolactinaemia and hypogonadotrophic amenorrhoea. It also observes the drug-induced situation resulting from the use of the gonadotrophin-releasing hormone analogue, goserelin. Bone density was measured using dual-energy X-ray absorptiometry (DEXA). This is very acceptable to subjects since the radiation dose is small and the low reproducibility makes short term longitudinal study possible. A biochemical assessment was also made measuring plasma osteocalcin and the cross-links pyridinoline and deoxypyridinoline excreted in the urine. In the group of early menopausal women we were unable to predict absolute BMD at either lumbar spine or femoral neck from personal risk factors. Body weight was the strongest predictor of bone density at each site. Rates of bone loss were greatest in the smokers and in those closest to their last menstrual period. The biochemical assessment was unhelpful. Those women with hypogonadotrophic hypogonadism had significantly lower bone density than age-matched normals. These were mainly young women with weight loss-related amenorrhoea. Those women with hyperprolactinaemia had a very normal bone density. In both groups no change in bone density was seen over the study period. The greatest reductions in bone density were seen in the breast feeding women and in those receiving treatment with the GnRH analogue, goserelin. In summary, the observed situations have resulted in changes in bone density. The magnitude of these changes are small and it is not clear how these small changes influence clinical outcome.