[Osteoporosis in Klinefelter's syndrome Quantitative bone histological data in 5 cases and relationship with hormonal...

The histomorphometric data obtained from nondecalcified iliac bone biopsies in 5 patients with Klinefelter's syndrome (KS), low back pain and histologically confirmed osteoporosis are presented. The data were compared with those of 3 other patients with osteoporosis and hypogonadism unconnected with KS. The results were identical in both groups, with rarefied spongy bone and strongly depressed osteoblastic activity, the latter being expressed morphologically by a decrease in osteoid seam thickness and dynamically by a low appositional rate. As both groups had low androgen levels, it is suggested that bone rarefaction in KS is associated with the hormonal deficiency and not directly due to the chromosomal abnormality. T e mechanism of action of androgens on bone tissue is discussed.