BONE MASS AND MINERAL METABOLISM IN KLINEFELTERS-SYNDROME

A reduced bone mineral density (BMD) is frequently observed in hypogon adal males; however, very little is known on bone and mineral metaboli sm in Klinefelter's syndrome (KS). In this study 32 XXY KS patients an d 24 healthy age-matched male controls were examined. Serum total and free testosterone (TT and FT) were significantly lower in patients tha n in controls (TT in KS, 15.1 +/- 7.8 nmol/l; controls, 30.4 +/- 9.1; p <0.001. FT in KS, 81.8 +/- 24.9 pmol/l; controls, 135.7 +/- 16.4; p <0.001). 17 beta-Estradiol was slightly higher in KS patients (KS, 49. 0 +/- 27.1 pg/ml; controls, 39.3 +/- 16.4 pg/ml), but the difference w as not significant. BMD, measured at the spine (L2-4) and at the proxi mal epiphysis of the left femur, was similar in patients and in the co ntrol group spine: KS, 1.016 +/- 0.142; controls, 1.085 +/- 0.144 g/cm (2); p = not significant. Femoral neck: KS, 0.996 +/- 0.149; controls, 0.926 +/- 0.122 g/cm(2); p = not significant). Bone GLA protein (BGP) was significantly higher in the KS group (12.7 +/- 4.8 vs 8.9 +/- 5.2 ng/ml; p <0.02), while serum calcium, serum phosphate, calciotrophic hormones and the fasting urinary hydroxyproline/creatinine ratio (OHP/ Creat) were similar in the two groups. A positive relationship between FT and both spine and femoral BMD was found in KS patients. Furthermo re, OHP/Creat ratio was inversely related to BMD at the femur, and pos itively related to BGP in KS patients, but not in normal subjects. The se findings suggest that (1) KS patients have normal bone mass, most p robably because the hypogonadism is moderate; and (2) patients with lo wer bone mass appear to have higher bone turnover.